some progress

node_modules/mongoose/lib/helpers/aggregate/prepareDiscriminatorPipeline.js

@@ -0,0 +1,39 @@
+'use strict';
+
+module.exports = function prepareDiscriminatorPipeline(pipeline, schema, prefix) {
+  const discriminatorMapping = schema && schema.discriminatorMapping;
+  prefix = prefix || '';
+
+  if (discriminatorMapping && !discriminatorMapping.isRoot) {
+    const originalPipeline = pipeline;
+    const filterKey = (prefix.length > 0 ? prefix + '.' : prefix) + discriminatorMapping.key;
+    const discriminatorValue = discriminatorMapping.value;
+
+    // If the first pipeline stage is a match and it doesn't specify a `__t`
+    // key, add the discriminator key to it. This allows for potential
+    // aggregation query optimizations not to be disturbed by this feature.
+    if (originalPipeline[0] != null &&
+        originalPipeline[0].$match &&
+        (originalPipeline[0].$match[filterKey] === undefined || originalPipeline[0].$match[filterKey] === discriminatorValue)) {
+      originalPipeline[0].$match[filterKey] = discriminatorValue;
+      // `originalPipeline` is a ref, so there's no need for
+      // aggregate._pipeline = originalPipeline
+    } else if (originalPipeline[0] != null && originalPipeline[0].$geoNear) {
+      originalPipeline[0].$geoNear.query =
+          originalPipeline[0].$geoNear.query || {};
+      originalPipeline[0].$geoNear.query[filterKey] = discriminatorValue;
+    } else if (originalPipeline[0] != null && originalPipeline[0].$search) {
+      if (originalPipeline[1] && originalPipeline[1].$match != null) {
+        originalPipeline[1].$match[filterKey] = originalPipeline[1].$match[filterKey] || discriminatorValue;
+      } else {
+        const match = {};
+        match[filterKey] = discriminatorValue;
+        originalPipeline.splice(1, 0, { $match: match });
+      }
+    } else {
+      const match = {};
+      match[filterKey] = discriminatorValue;
+      originalPipeline.unshift({ $match: match });
+    }
+  }
+};

node_modules/mongoose/lib/helpers/aggregate/stringifyFunctionOperators.js

@@ -0,0 +1,50 @@
+'use strict';
+
+module.exports = function stringifyFunctionOperators(pipeline) {
+  if (!Array.isArray(pipeline)) {
+    return;
+  }
+
+  for (const stage of pipeline) {
+    if (stage == null) {
+      continue;
+    }
+
+    const canHaveAccumulator = stage.$group || stage.$bucket || stage.$bucketAuto;
+    if (canHaveAccumulator != null) {
+      for (const key of Object.keys(canHaveAccumulator)) {
+        handleAccumulator(canHaveAccumulator[key]);
+      }
+    }
+
+    const stageType = Object.keys(stage)[0];
+    if (stageType && typeof stage[stageType] === 'object') {
+      const stageOptions = stage[stageType];
+      for (const key of Object.keys(stageOptions)) {
+        if (stageOptions[key] != null &&
+            stageOptions[key].$function != null &&
+            typeof stageOptions[key].$function.body === 'function') {
+          stageOptions[key].$function.body = stageOptions[key].$function.body.toString();
+        }
+      }
+    }
+
+    if (stage.$facet != null) {
+      for (const key of Object.keys(stage.$facet)) {
+        stringifyFunctionOperators(stage.$facet[key]);
+      }
+    }
+  }
+};
+
+function handleAccumulator(operator) {
+  if (operator == null || operator.$accumulator == null) {
+    return;
+  }
+
+  for (const key of ['init', 'accumulate', 'merge', 'finalize']) {
+    if (typeof operator.$accumulator[key] === 'function') {
+      operator.$accumulator[key] = String(operator.$accumulator[key]);
+    }
+  }
+}

node_modules/mongoose/lib/helpers/arrayDepth.js

@@ -0,0 +1,33 @@
+'use strict';
+
+module.exports = arrayDepth;
+
+function arrayDepth(arr) {
+  if (!Array.isArray(arr)) {
+    return { min: 0, max: 0, containsNonArrayItem: true };
+  }
+  if (arr.length === 0) {
+    return { min: 1, max: 1, containsNonArrayItem: false };
+  }
+  if (arr.length === 1 && !Array.isArray(arr[0])) {
+    return { min: 1, max: 1, containsNonArrayItem: false };
+  }
+
+  const res = arrayDepth(arr[0]);
+
+  for (let i = 1; i < arr.length; ++i) {
+    const _res = arrayDepth(arr[i]);
+    if (_res.min < res.min) {
+      res.min = _res.min;
+    }
+    if (_res.max > res.max) {
+      res.max = _res.max;
+    }
+    res.containsNonArrayItem = res.containsNonArrayItem || _res.containsNonArrayItem;
+  }
+
+  res.min = res.min + 1;
+  res.max = res.max + 1;
+
+  return res;
+}

node_modules/mongoose/lib/helpers/clone.js

@@ -0,0 +1,177 @@
+'use strict';
+
+const Decimal = require('../types/decimal128');
+const ObjectId = require('../types/objectid');
+const specialProperties = require('./specialProperties');
+const isMongooseObject = require('./isMongooseObject');
+const getFunctionName = require('./getFunctionName');
+const isBsonType = require('./isBsonType');
+const isMongooseArray = require('../types/array/isMongooseArray').isMongooseArray;
+const isObject = require('./isObject');
+const isPOJO = require('./isPOJO');
+const symbols = require('./symbols');
+const trustedSymbol = require('./query/trusted').trustedSymbol;
+
+/**
+ * Object clone with Mongoose natives support.
+ *
+ * If options.minimize is true, creates a minimal data object. Empty objects and undefined values will not be cloned. This makes the data payload sent to MongoDB as small as possible.
+ *
+ * Functions are never cloned.
+ *
+ * @param {Object} obj the object to clone
+ * @param {Object} options
+ * @param {Boolean} isArrayChild true if cloning immediately underneath an array. Special case for minimize.
+ * @return {Object} the cloned object
+ * @api private
+ */
+
+function clone(obj, options, isArrayChild) {
+  if (obj == null) {
+    return obj;
+  }
+
+  if (Array.isArray(obj)) {
+    return cloneArray(isMongooseArray(obj) ? obj.__array : obj, options);
+  }
+
+  if (isMongooseObject(obj)) {
+    // Single nested subdocs should apply getters later in `applyGetters()`
+    // when calling `toObject()`. See gh-7442, gh-8295
+    if (options && options._skipSingleNestedGetters && obj.$isSingleNested) {
+      options = Object.assign({}, options, { getters: false });
+    }
+    const isSingleNested = obj.$isSingleNested;
+
+    if (isPOJO(obj) && obj.$__ != null && obj._doc != null) {
+      return obj._doc;
+    }
+
+    let ret;
+    if (options && options.json && typeof obj.toJSON === 'function') {
+      ret = obj.toJSON(options);
+    } else {
+      ret = obj.toObject(options);
+    }
+
+    if (options && options.minimize && isSingleNested && Object.keys(ret).length === 0) {
+      return undefined;
+    }
+
+    return ret;
+  }
+
+  const objConstructor = obj.constructor;
+
+  if (objConstructor) {
+    switch (getFunctionName(objConstructor)) {
+      case 'Object':
+        return cloneObject(obj, options, isArrayChild);
+      case 'Date':
+        return new objConstructor(+obj);
+      case 'RegExp':
+        return cloneRegExp(obj);
+      default:
+        // ignore
+        break;
+    }
+  }
+
+  if (isBsonType(obj, 'ObjectId')) {
+    return new ObjectId(obj.id);
+  }
+
+  if (isBsonType(obj, 'Decimal128')) {
+    if (options && options.flattenDecimals) {
+      return obj.toJSON();
+    }
+    return Decimal.fromString(obj.toString());
+  }
+
+  // object created with Object.create(null)
+  if (!objConstructor && isObject(obj)) {
+    return cloneObject(obj, options, isArrayChild);
+  }
+
+  if (typeof obj === 'object' && obj[symbols.schemaTypeSymbol]) {
+    return obj.clone();
+  }
+
+  // If we're cloning this object to go into a MongoDB command,
+  // and there's a `toBSON()` function, assume this object will be
+  // stored as a primitive in MongoDB and doesn't need to be cloned.
+  if (options && options.bson && typeof obj.toBSON === 'function') {
+    return obj;
+  }
+
+  if (typeof obj.valueOf === 'function') {
+    return obj.valueOf();
+  }
+
+  return cloneObject(obj, options, isArrayChild);
+}
+module.exports = clone;
+
+/*!
+ * ignore
+ */
+
+function cloneObject(obj, options, isArrayChild) {
+  const minimize = options && options.minimize;
+  const omitUndefined = options && options.omitUndefined;
+  const seen = options && options._seen;
+  const ret = {};
+  let hasKeys;
+
+  if (seen && seen.has(obj)) {
+    return seen.get(obj);
+  } else if (seen) {
+    seen.set(obj, ret);
+  }
+  if (trustedSymbol in obj) {
+    ret[trustedSymbol] = obj[trustedSymbol];
+  }
+
+  let i = 0;
+  let key = '';
+  const keys = Object.keys(obj);
+  const len = keys.length;
+
+  for (i = 0; i < len; ++i) {
+    if (specialProperties.has(key = keys[i])) {
+      continue;
+    }
+
+    // Don't pass `isArrayChild` down
+    const val = clone(obj[key], options, false);
+
+    if ((minimize === false || omitUndefined) && typeof val === 'undefined') {
+      delete ret[key];
+    } else if (minimize !== true || (typeof val !== 'undefined')) {
+      hasKeys || (hasKeys = true);
+      ret[key] = val;
+    }
+  }
+
+  return minimize && !isArrayChild ? hasKeys && ret : ret;
+}
+
+function cloneArray(arr, options) {
+  let i = 0;
+  const len = arr.length;
+  const ret = new Array(len);
+  for (i = 0; i < len; ++i) {
+    ret[i] = clone(arr[i], options, true);
+  }
+
+  return ret;
+}
+
+function cloneRegExp(regexp) {
+  const ret = new RegExp(regexp.source, regexp.flags);
+
+  if (ret.lastIndex !== regexp.lastIndex) {
+    ret.lastIndex = regexp.lastIndex;
+  }
+  return ret;
+}

node_modules/mongoose/lib/helpers/common.js

@@ -0,0 +1,127 @@
+'use strict';
+
+/*!
+ * Module dependencies.
+ */
+
+const Binary = require('bson').Binary;
+const isBsonType = require('./isBsonType');
+const isMongooseObject = require('./isMongooseObject');
+const MongooseError = require('../error');
+const util = require('util');
+
+exports.flatten = flatten;
+exports.modifiedPaths = modifiedPaths;
+
+/*!
+ * ignore
+ */
+
+function flatten(update, path, options, schema) {
+  let keys;
+  if (update && isMongooseObject(update) && !Buffer.isBuffer(update)) {
+    keys = Object.keys(update.toObject({ transform: false, virtuals: false }) || {});
+  } else {
+    keys = Object.keys(update || {});
+  }
+
+  const numKeys = keys.length;
+  const result = {};
+  path = path ? path + '.' : '';
+
+  for (let i = 0; i < numKeys; ++i) {
+    const key = keys[i];
+    const val = update[key];
+    result[path + key] = val;
+
+    // Avoid going into mixed paths if schema is specified
+    const keySchema = schema && schema.path && schema.path(path + key);
+    const isNested = schema && schema.nested && schema.nested[path + key];
+    if (keySchema && keySchema.instance === 'Mixed') continue;
+
+    if (shouldFlatten(val)) {
+      if (options && options.skipArrays && Array.isArray(val)) {
+        continue;
+      }
+      const flat = flatten(val, path + key, options, schema);
+      for (const k in flat) {
+        result[k] = flat[k];
+      }
+      if (Array.isArray(val)) {
+        result[path + key] = val;
+      }
+    }
+
+    if (isNested) {
+      const paths = Object.keys(schema.paths);
+      for (const p of paths) {
+        if (p.startsWith(path + key + '.') && !result.hasOwnProperty(p)) {
+          result[p] = void 0;
+        }
+      }
+    }
+  }
+
+  return result;
+}
+
+/*!
+ * ignore
+ */
+
+function modifiedPaths(update, path, result, recursion = null) {
+  if (update == null || typeof update !== 'object') {
+    return;
+  }
+
+  if (recursion == null) {
+    recursion = {
+      raw: { update, path },
+      trace: new WeakSet()
+    };
+  }
+
+  if (recursion.trace.has(update)) {
+    throw new MongooseError(`a circular reference in the update value, updateValue:
+${util.inspect(recursion.raw.update, { showHidden: false, depth: 1 })}
+updatePath: '${recursion.raw.path}'`);
+  }
+  recursion.trace.add(update);
+
+  const keys = Object.keys(update || {});
+  const numKeys = keys.length;
+  result = result || {};
+  path = path ? path + '.' : '';
+
+  for (let i = 0; i < numKeys; ++i) {
+    const key = keys[i];
+    let val = update[key];
+
+    const _path = path + key;
+    result[_path] = true;
+    if (!Buffer.isBuffer(val) && isMongooseObject(val)) {
+      val = val.toObject({ transform: false, virtuals: false });
+    }
+    if (shouldFlatten(val)) {
+      modifiedPaths(val, path + key, result, recursion);
+    }
+  }
+  recursion.trace.delete(update);
+
+  return result;
+}
+
+/*!
+ * ignore
+ */
+
+function shouldFlatten(val) {
+  return val &&
+      typeof val === 'object' &&
+      !(val instanceof Date) &&
+      !isBsonType(val, 'ObjectId') &&
+      (!Array.isArray(val) || val.length !== 0) &&
+      !(val instanceof Buffer) &&
+      !isBsonType(val, 'Decimal128') &&
+      !(val instanceof Binary);
+}

node_modules/mongoose/lib/helpers/cursor/eachAsync.js

@@ -0,0 +1,225 @@
+'use strict';
+
+/*!
+ * Module dependencies.
+ */
+
+const EachAsyncMultiError = require('../../error/eachAsyncMultiError');
+const immediate = require('../immediate');
+
+/**
+ * Execute `fn` for every document in the cursor. If `fn` returns a promise,
+ * will wait for the promise to resolve before iterating on to the next one.
+ * Returns a promise that resolves when done.
+ *
+ * @param {Function} next the thunk to call to get the next document
+ * @param {Function} fn
+ * @param {Object} options
+ * @param {Number} [options.batchSize=null] if set, Mongoose will call `fn` with an array of at most `batchSize` documents, instead of a single document
+ * @param {Number} [options.parallel=1] maximum number of `fn` calls that Mongoose will run in parallel
+ * @param {AbortSignal} [options.signal] allow cancelling this eachAsync(). Once the abort signal is fired, `eachAsync()` will immediately fulfill the returned promise (or call the callback) and not fetch any more documents.
+ * @return {Promise}
+ * @api public
+ * @method eachAsync
+ */
+
+module.exports = async function eachAsync(next, fn, options) {
+  const parallel = options.parallel || 1;
+  const batchSize = options.batchSize;
+  const signal = options.signal;
+  const continueOnError = options.continueOnError;
+  const aggregatedErrors = [];
+  const enqueue = asyncQueue();
+
+  let aborted = false;
+
+  return new Promise((resolve, reject) => {
+    if (signal != null) {
+      if (signal.aborted) {
+        return resolve(null);
+      }
+
+      signal.addEventListener('abort', () => {
+        aborted = true;
+        return resolve(null);
+      }, { once: true });
+    }
+
+    if (batchSize != null) {
+      if (typeof batchSize !== 'number') {
+        throw new TypeError('batchSize must be a number');
+      } else if (!Number.isInteger(batchSize)) {
+        throw new TypeError('batchSize must be an integer');
+      } else if (batchSize < 1) {
+        throw new TypeError('batchSize must be at least 1');
+      }
+    }
+
+    iterate((err, res) => {
+      if (err != null) {
+        return reject(err);
+      }
+      resolve(res);
+    });
+  });
+
+  function iterate(finalCallback) {
+    let handleResultsInProgress = 0;
+    let currentDocumentIndex = 0;
+
+    let error = null;
+    for (let i = 0; i < parallel; ++i) {
+      enqueue(createFetch());
+    }
+
+    function createFetch() {
+      let documentsBatch = [];
+      let drained = false;
+
+      return fetch;
+
+      function fetch(done) {
+        if (drained || aborted) {
+          return done();
+        } else if (error) {
+          return done();
+        }
+
+        next(function(err, doc) {
+          if (error != null) {
+            return done();
+          }
+          if (err != null) {
+            if (err.name === 'MongoCursorExhaustedError') {
+              // We may end up calling `next()` multiple times on an exhausted
+              // cursor, which leads to an error. In case cursor is exhausted,
+              // just treat it as if the cursor returned no document, which is
+              // how a cursor indicates it is exhausted.
+              doc = null;
+            } else if (continueOnError) {
+              aggregatedErrors.push(err);
+            } else {
+              error = err;
+              finalCallback(err);
+              return done();
+            }
+          }
+          if (doc == null) {
+            drained = true;
+            if (handleResultsInProgress <= 0) {
+              const finalErr = continueOnError ?
+                createEachAsyncMultiError(aggregatedErrors) :
+                error;
+
+              finalCallback(finalErr);
+            } else if (batchSize && documentsBatch.length) {
+              handleNextResult(documentsBatch, currentDocumentIndex++, handleNextResultCallBack);
+            }
+            return done();
+          }
+
+          ++handleResultsInProgress;
+
+          // Kick off the subsequent `next()` before handling the result, but
+          // make sure we know that we still have a result to handle re: #8422
+          immediate(() => done());
+
+          if (batchSize) {
+            documentsBatch.push(doc);
+          }
+
+          // If the current documents size is less than the provided batch size don't process the documents yet
+          if (batchSize && documentsBatch.length !== batchSize) {
+            immediate(() => enqueue(fetch));
+            return;
+          }
+
+          const docsToProcess = batchSize ? documentsBatch : doc;
+
+          function handleNextResultCallBack(err) {
+            if (batchSize) {
+              handleResultsInProgress -= documentsBatch.length;
+              documentsBatch = [];
+            } else {
+              --handleResultsInProgress;
+            }
+            if (err != null) {
+              if (continueOnError) {
+                aggregatedErrors.push(err);
+              } else {
+                error = err;
+                return finalCallback(err);
+              }
+            }
+            if ((drained || aborted) && handleResultsInProgress <= 0) {
+              const finalErr = continueOnError ?
+                createEachAsyncMultiError(aggregatedErrors) :
+                error;
+              return finalCallback(finalErr);
+            }
+
+            immediate(() => enqueue(fetch));
+          }
+
+          handleNextResult(docsToProcess, currentDocumentIndex++, handleNextResultCallBack);
+        });
+      }
+    }
+  }
+
+  function handleNextResult(doc, i, callback) {
+    let maybePromise;
+    try {
+      maybePromise = fn(doc, i);
+    } catch (err) {
+      return callback(err);
+    }
+    if (maybePromise && typeof maybePromise.then === 'function') {
+      maybePromise.then(
+        function() { callback(null); },
+        function(error) {
+          callback(error || new Error('`eachAsync()` promise rejected without error'));
+        });
+    } else {
+      callback(null);
+    }
+  }
+};
+
+// `next()` can only execute one at a time, so make sure we always execute
+// `next()` in series, while still allowing multiple `fn()` instances to run
+// in parallel.
+function asyncQueue() {
+  const _queue = [];
+  let inProgress = null;
+  let id = 0;
+
+  return function enqueue(fn) {
+    if (
+      inProgress === null &&
+      _queue.length === 0
+    ) {
+      inProgress = id++;
+      return fn(_step);
+    }
+    _queue.push(fn);
+  };
+
+  function _step() {
+    if (_queue.length !== 0) {
+      inProgress = id++;
+      const fn = _queue.shift();
+      fn(_step);
+    } else {
+      inProgress = null;
+    }
+  }
+}
+
+function createEachAsyncMultiError(aggregatedErrors) {
+  if (aggregatedErrors.length === 0) {
+    return null;
+  }
+
+  return new EachAsyncMultiError(aggregatedErrors);
+}

node_modules/mongoose/lib/helpers/discriminator/areDiscriminatorValuesEqual.js

@@ -0,0 +1,16 @@
+'use strict';
+
+const isBsonType = require('../isBsonType');
+
+module.exports = function areDiscriminatorValuesEqual(a, b) {
+  if (typeof a === 'string' && typeof b === 'string') {
+    return a === b;
+  }
+  if (typeof a === 'number' && typeof b === 'number') {
+    return a === b;
+  }
+  if (isBsonType(a, 'ObjectId') && isBsonType(b, 'ObjectId')) {
+    return a.toString() === b.toString();
+  }
+  return false;
+};

node_modules/mongoose/lib/helpers/discriminator/checkEmbeddedDiscriminatorKeyProjection.js

@@ -0,0 +1,12 @@
+'use strict';
+
+module.exports = function checkEmbeddedDiscriminatorKeyProjection(userProjection, path, schema, selected, addedPaths) {
+  const userProjectedInPath = Object.keys(userProjection).
+    reduce((cur, key) => cur || key.startsWith(path + '.'), false);
+  const _discriminatorKey = path + '.' + schema.options.discriminatorKey;
+  if (!userProjectedInPath &&
+      addedPaths.length === 1 &&
+      addedPaths[0] === _discriminatorKey) {
+    selected.splice(selected.indexOf(_discriminatorKey), 1);
+  }
+};

node_modules/mongoose/lib/helpers/discriminator/getConstructor.js

@@ -0,0 +1,26 @@
+'use strict';
+
+const getDiscriminatorByValue = require('./getDiscriminatorByValue');
+
+/**
+ * Find the correct constructor, taking into account discriminators
+ * @api private
+ */
+
+module.exports = function getConstructor(Constructor, value) {
+  const discriminatorKey = Constructor.schema.options.discriminatorKey;
+  if (value != null &&
+      Constructor.discriminators &&
+      value[discriminatorKey] != null) {
+    if (Constructor.discriminators[value[discriminatorKey]]) {
+      Constructor = Constructor.discriminators[value[discriminatorKey]];
+    } else {
+      const constructorByValue = getDiscriminatorByValue(Constructor.discriminators, value[discriminatorKey]);
+      if (constructorByValue) {
+        Constructor = constructorByValue;
+      }
+    }
+  }
+
+  return Constructor;
+};

node_modules/mongoose/lib/helpers/discriminator/getDiscriminatorByValue.js

@@ -0,0 +1,28 @@
+'use strict';
+
+const areDiscriminatorValuesEqual = require('./areDiscriminatorValuesEqual');
+
+/**
+ * returns discriminator by discriminatorMapping.value
+ *
+ * @param {Object} discriminators
+ * @param {string} value
+ * @api private
+ */
+
+module.exports = function getDiscriminatorByValue(discriminators, value) {
+  if (discriminators == null) {
+    return null;
+  }
+  for (const name of Object.keys(discriminators)) {
+    const it = discriminators[name];
+    if (
+      it.schema &&
+      it.schema.discriminatorMapping &&
+      areDiscriminatorValuesEqual(it.schema.discriminatorMapping.value, value)
+    ) {
+      return it;
+    }
+  }
+  return null;
+};

node_modules/mongoose/lib/helpers/discriminator/getSchemaDiscriminatorByValue.js

@@ -0,0 +1,27 @@
+'use strict';
+
+const areDiscriminatorValuesEqual = require('./areDiscriminatorValuesEqual');
+
+/**
+ * returns discriminator by discriminatorMapping.value
+ *
+ * @param {Schema} schema
+ * @param {string} value
+ * @api private
+ */
+
+module.exports = function getSchemaDiscriminatorByValue(schema, value) {
+  if (schema == null || schema.discriminators == null) {
+    return null;
+  }
+  for (const key of Object.keys(schema.discriminators)) {
+    const discriminatorSchema = schema.discriminators[key];
+    if (discriminatorSchema.discriminatorMapping == null) {
+      continue;
+    }
+    if (areDiscriminatorValuesEqual(discriminatorSchema.discriminatorMapping.value, value)) {
+      return discriminatorSchema;
+    }
+  }
+  return null;
+};

node_modules/mongoose/lib/helpers/discriminator/mergeDiscriminatorSchema.js

@@ -0,0 +1,75 @@
+'use strict';
+const schemaMerge = require('../schema/merge');
+const specialProperties = require('../../helpers/specialProperties');
+const isBsonType = require('../../helpers/isBsonType');
+const ObjectId = require('../../types/objectid');
+const isObject = require('../../helpers/isObject');
+/**
+ * Merges `from` into `to` without overwriting existing properties.
+ *
+ * @param {Object} to
+ * @param {Object} from
+ * @param {String} [path]
+ * @api private
+ */
+
+module.exports = function mergeDiscriminatorSchema(to, from, path, seen) {
+  const keys = Object.keys(from);
+  let i = 0;
+  const len = keys.length;
+  let key;
+
+  path = path || '';
+  seen = seen || new WeakSet();
+
+  if (seen.has(from)) {
+    return;
+  }
+  seen.add(from);
+
+  while (i < len) {
+    key = keys[i++];
+    if (!path) {
+      if (key === 'discriminators' ||
+        key === 'base' ||
+        key === '_applyDiscriminators' ||
+        key === '_userProvidedOptions' ||
+        key === 'options') {
+        continue;
+      }
+    }
+    if (path === 'tree' && from != null && from.instanceOfSchema) {
+      continue;
+    }
+    if (specialProperties.has(key)) {
+      continue;
+    }
+    if (to[key] == null) {
+      to[key] = from[key];
+    } else if (isObject(from[key])) {
+      if (!isObject(to[key])) {
+        to[key] = {};
+      }
+      if (from[key] != null) {
+        // Skip merging schemas if we're creating a discriminator schema and
+        // base schema has a given path as a single nested but discriminator schema
+        // has the path as a document array, or vice versa (gh-9534)
+        if ((from[key].$isSingleNested && to[key].$isMongooseDocumentArray) ||
+              (from[key].$isMongooseDocumentArray && to[key].$isSingleNested)) {
+          continue;
+        } else if (from[key].instanceOfSchema) {
+          if (to[key].instanceOfSchema) {
+            schemaMerge(to[key], from[key].clone(), true);
+          } else {
+            to[key] = from[key].clone();
+          }
+          continue;
+        } else if (isBsonType(from[key], 'ObjectId')) {
+          to[key] = new ObjectId(from[key]);
+          continue;
+        }
+      }
+      mergeDiscriminatorSchema(to[key], from[key], path ? path + '.' + key : key, seen);
+    }
+  }
+};

node_modules/mongoose/lib/helpers/document/applyDefaults.js

@@ -0,0 +1,126 @@
+'use strict';
+
+module.exports = function applyDefaults(doc, fields, exclude, hasIncludedChildren, isBeforeSetters, pathsToSkip) {
+  const paths = Object.keys(doc.$__schema.paths);
+  const plen = paths.length;
+
+  for (let i = 0; i < plen; ++i) {
+    let def;
+    let curPath = '';
+    const p = paths[i];
+
+    if (p === '_id' && doc.$__.skipId) {
+      continue;
+    }
+
+    const type = doc.$__schema.paths[p];
+    const path = type.splitPath();
+    const len = path.length;
+    let included = false;
+    let doc_ = doc._doc;
+    for (let j = 0; j < len; ++j) {
+      if (doc_ == null) {
+        break;
+      }
+
+      const piece = path[j];
+      curPath += (!curPath.length ? '' : '.') + piece;
+
+      if (exclude === true) {
+        if (curPath in fields) {
+          break;
+        }
+      } else if (exclude === false && fields && !included) {
+        const hasSubpaths = type.$isSingleNested || type.$isMongooseDocumentArray;
+        if (curPath in fields || (j === len - 1 && hasSubpaths && hasIncludedChildren != null && hasIncludedChildren[curPath])) {
+          included = true;
+        } else if (hasIncludedChildren != null && !hasIncludedChildren[curPath]) {
+          break;
+        }
+      }
+
+      if (j === len - 1) {
+        if (doc_[piece] !== void 0) {
+          break;
+        }
+
+        if (isBeforeSetters != null) {
+          if (typeof type.defaultValue === 'function') {
+            if (!type.defaultValue.$runBeforeSetters && isBeforeSetters) {
+              break;
+            }
+            if (type.defaultValue.$runBeforeSetters && !isBeforeSetters) {
+              break;
+            }
+          } else if (!isBeforeSetters) {
+            // Non-function defaults should always run **before** setters
+            continue;
+          }
+        }
+
+        if (pathsToSkip && pathsToSkip[curPath]) {
+          break;
+        }
+
+        if (fields && exclude !== null) {
+          if (exclude === true) {
+            // apply defaults to all non-excluded fields
+            if (p in fields) {
+              continue;
+            }
+
+            try {
+              def = type.getDefault(doc, false);
+            } catch (err) {
+              doc.invalidate(p, err);
+              break;
+            }
+
+            if (typeof def !== 'undefined') {
+              doc_[piece] = def;
+              applyChangeTracking(doc, p);
+            }
+          } else if (included) {
+            // selected field
+            try {
+              def = type.getDefault(doc, false);
+            } catch (err) {
+              doc.invalidate(p, err);
+              break;
+            }
+
+            if (typeof def !== 'undefined') {
+              doc_[piece] = def;
+              applyChangeTracking(doc, p);
+            }
+          }
+        } else {
+          try {
+            def = type.getDefault(doc, false);
+          } catch (err) {
+            doc.invalidate(p, err);
+            break;
+          }
+
+          if (typeof def !== 'undefined') {
+            doc_[piece] = def;
+            applyChangeTracking(doc, p);
+          }
+        }
+      } else {
+        doc_ = doc_[piece];
+      }
+    }
+  }
+};
+
+/*!
+ * ignore
+ */
+
+function applyChangeTracking(doc, fullPath) {
+  doc.$__.activePaths.default(fullPath);
+  if (doc.$isSubdocument && doc.$isSingleNested && doc.$parent() != null) {
+    doc.$parent().$__.activePaths.default(doc.$__pathRelativeToParent(fullPath));
+  }
+}

node_modules/mongoose/lib/helpers/document/cleanModifiedSubpaths.js

@@ -0,0 +1,35 @@
+'use strict';
+
+/*!
+ * ignore
+ */
+
+module.exports = function cleanModifiedSubpaths(doc, path, options) {
+  options = options || {};
+  const skipDocArrays = options.skipDocArrays;
+
+  let deleted = 0;
+  if (!doc) {
+    return deleted;
+  }
+
+  for (const modifiedPath of Object.keys(doc.$__.activePaths.getStatePaths('modify'))) {
+    if (skipDocArrays) {
+      const schemaType = doc.$__schema.path(modifiedPath);
+      if (schemaType && schemaType.$isMongooseDocumentArray) {
+        continue;
+      }
+    }
+    if (modifiedPath.startsWith(path + '.')) {
+      doc.$__.activePaths.clearPath(modifiedPath);
+      ++deleted;
+
+      if (doc.$isSubdocument) {
+        const owner = doc.ownerDocument();
+        const fullPath = doc.$__fullPath(modifiedPath);
+        owner.$__.activePaths.clearPath(fullPath);
+      }
+    }
+  }
+  return deleted;
+};

node_modules/mongoose/lib/helpers/document/compile.js

@@ -0,0 +1,228 @@
+'use strict';
+
+const clone = require('../../helpers/clone');
+const documentSchemaSymbol = require('../../helpers/symbols').documentSchemaSymbol;
+const internalToObjectOptions = require('../../options').internalToObjectOptions;
+const utils = require('../../utils');
+
+let Document;
+const getSymbol = require('../../helpers/symbols').getSymbol;
+const scopeSymbol = require('../../helpers/symbols').scopeSymbol;
+
+const isPOJO = utils.isPOJO;
+
+/*!
+ * exports
+ */
+
+exports.compile = compile;
+exports.defineKey = defineKey;
+
+const _isEmptyOptions = Object.freeze({
+  minimize: true,
+  virtuals: false,
+  getters: false,
+  transform: false
+});
+
+/**
+ * Compiles schemas.
+ * @param {Object} tree
+ * @param {Any} proto
+ * @param {String} prefix
+ * @param {Object} options
+ * @api private
+ */
+
+function compile(tree, proto, prefix, options) {
+  Document = Document || require('../../document');
+  const typeKey = options.typeKey;
+
+  for (const key of Object.keys(tree)) {
+    const limb = tree[key];
+
+    const hasSubprops = isPOJO(limb) &&
+      Object.keys(limb).length > 0 &&
+      (!limb[typeKey] || (typeKey === 'type' && isPOJO(limb.type) && limb.type.type));
+    const subprops = hasSubprops ? limb : null;
+
+    defineKey({ prop: key, subprops: subprops, prototype: proto, prefix: prefix, options: options });
+  }
+}
+
+/**
+ * Defines the accessor named prop on the incoming prototype.
+ * @param {Object} options
+ * @param {String} options.prop
+ * @param {Boolean} options.subprops
+ * @param {Any} options.prototype
+ * @param {String} [options.prefix]
+ * @param {Object} options.options
+ * @api private
+ */
+
+function defineKey({ prop, subprops, prototype, prefix, options }) {
+  Document = Document || require('../../document');
+  const path = (prefix ? prefix + '.' : '') + prop;
+  prefix = prefix || '';
+
+  if (subprops) {
+    Object.defineProperty(prototype, prop, {
+      enumerable: true,
+      configurable: true,
+      get: function() {
+        const _this = this;
+        if (!this.$__.getters) {
+          this.$__.getters = {};
+        }
+
+        if (!this.$__.getters[path]) {
+          const nested = Object.create(Document.prototype, getOwnPropertyDescriptors(this));
+
+          // save scope for nested getters/setters
+          if (!prefix) {
+            nested.$__[scopeSymbol] = this;
+          }
+          nested.$__.nestedPath = path;
+
+          Object.defineProperty(nested, 'schema', {
+            enumerable: false,
+            configurable: true,
+            writable: false,
+            value: prototype.schema
+          });
+
+          Object.defineProperty(nested, '$__schema', {
+            enumerable: false,
+            configurable: true,
+            writable: false,
+            value: prototype.schema
+          });
+
+          Object.defineProperty(nested, documentSchemaSymbol, {
+            enumerable: false,
+            configurable: true,
+            writable: false,
+            value: prototype.schema
+          });
+
+          Object.defineProperty(nested, 'toObject', {
+            enumerable: false,
+            configurable: true,
+            writable: false,
+            value: function() {
+              return clone(_this.get(path, null, {
+                virtuals: this &&
+                  this.schema &&
+                  this.schema.options &&
+                  this.schema.options.toObject &&
+                  this.schema.options.toObject.virtuals || null
+              }));
+            }
+          });
+
+          Object.defineProperty(nested, '$__get', {
+            enumerable: false,
+            configurable: true,
+            writable: false,
+            value: function() {
+              return _this.get(path, null, {
+                virtuals: this && this.schema && this.schema.options && this.schema.options.toObject && this.schema.options.toObject.virtuals || null
+              });
+            }
+          });
+
+          Object.defineProperty(nested, 'toJSON', {
+            enumerable: false,
+            configurable: true,
+            writable: false,
+            value: function() {
+              return _this.get(path, null, {
+                virtuals: this && this.schema && this.schema.options && this.schema.options.toJSON && this.schema.options.toJSON.virtuals || null
+              });
+            }
+          });
+
+          Object.defineProperty(nested, '$__isNested', {
+            enumerable: false,
+            configurable: true,
+            writable: false,
+            value: true
+          });
+
+          Object.defineProperty(nested, '$isEmpty', {
+            enumerable: false,
+            configurable: true,
+            writable: false,
+            value: function() {
+              return Object.keys(this.get(path, null, _isEmptyOptions) || {}).length === 0;
+            }
+          });
+
+          Object.defineProperty(nested, '$__parent', {
+            enumerable: false,
+            configurable: true,
+            writable: false,
+            value: this
+          });
+
+          compile(subprops, nested, path, options);
+          this.$__.getters[path] = nested;
+        }
+
+        return this.$__.getters[path];
+      },
+      set: function(v) {
+        if (v != null && v.$__isNested) {
+          // Convert top-level to POJO, but leave subdocs hydrated so `$set`
+          // can handle them. See gh-9293.
+          v = v.$__get();
+        } else if (v instanceof Document && !v.$__isNested) {
+          v = v.$toObject(internalToObjectOptions);
+        }
+        const doc = this.$__[scopeSymbol] || this;
+        doc.$set(path, v);
+      }
+    });
+  } else {
+    Object.defineProperty(prototype, prop, {
+      enumerable: true,
+      configurable: true,
+      get: function() {
+        return this[getSymbol].call(this.$__[scopeSymbol] || this, path);
+      },
+      set: function(v) {
+        this.$set.call(this.$__[scopeSymbol] || this, path, v);
+      }
+    });
+  }
+}
+
+// gets descriptors for all properties of `object`
+// makes all properties non-enumerable to match previous behavior to #2211
+function getOwnPropertyDescriptors(object) {
+  const result = {};
+
+  Object.getOwnPropertyNames(object).forEach(function(key) {
+    const skip = [
+      'isNew',
+      '$__',
+      '$errors',
+      'errors',
+      '_doc',
+      '$locals',
+      '$op',
+      '__parentArray',
+      '__index',
+      '$isDocumentArrayElement'
+    ].indexOf(key) === -1;
+    if (skip) {
+      return;
+    }
+
+    result[key] = Object.getOwnPropertyDescriptor(object, key);
+    result[key].enumerable = false;
+  });
+
+  return result;
+}

node_modules/mongoose/lib/helpers/document/getEmbeddedDiscriminatorPath.js

@@ -0,0 +1,50 @@
+'use strict';
+
+const get = require('../get');
+const getSchemaDiscriminatorByValue = require('../discriminator/getSchemaDiscriminatorByValue');
+
+/**
+ * Like `schema.path()`, except with a document, because impossible to
+ * determine path type without knowing the embedded discriminator key.
+ * @param {Document} doc
+ * @param {String} path
+ * @param {Object} [options]
+ * @api private
+ */
+
+module.exports = function getEmbeddedDiscriminatorPath(doc, path, options) {
+  options = options || {};
+  const typeOnly = options.typeOnly;
+  const parts = path.indexOf('.') === -1 ? [path] : path.split('.');
+  let schemaType = null;
+  let type = 'adhocOrUndefined';
+
+  const schema = getSchemaDiscriminatorByValue(doc.schema, doc.get(doc.schema.options.discriminatorKey)) || doc.schema;
+
+  for (let i = 0; i < parts.length; ++i) {
+    const subpath = parts.slice(0, i + 1).join('.');
+    schemaType = schema.path(subpath);
+    if (schemaType == null) {
+      type = 'adhocOrUndefined';
+      continue;
+    }
+    if (schemaType.instance === 'Mixed') {
+      return typeOnly ? 'real' : schemaType;
+    }
+    type = schema.pathType(subpath);
+    if ((schemaType.$isSingleNested || schemaType.$isMongooseDocumentArrayElement) &&
+    schemaType.schema.discriminators != null) {
+      const discriminators = schemaType.schema.discriminators;
+      const discriminatorKey = doc.get(subpath + '.' +
+        get(schemaType, 'schema.options.discriminatorKey'));
+      if (discriminatorKey == null || discriminators[discriminatorKey] == null) {
+        continue;
+      }
+      const rest = parts.slice(i + 1).join('.');
+      return getEmbeddedDiscriminatorPath(doc.get(subpath), rest, options);
+    }
+  }
+
+  // Are we getting the whole schema or just the type, 'real', 'nested', etc.
+  return typeOnly ? type : schemaType;
+};

node_modules/mongoose/lib/helpers/document/handleSpreadDoc.js

@@ -0,0 +1,35 @@
+'use strict';
+
+const utils = require('../../utils');
+
+const keysToSkip = new Set(['__index', '__parentArray', '_doc']);
+
+/**
+ * Using spread operator on a Mongoose document gives you a
+ * POJO that has a tendency to cause infinite recursion. So
+ * we use this function on `set()` to prevent that.
+ */
+
+module.exports = function handleSpreadDoc(v, includeExtraKeys) {
+  if (utils.isPOJO(v) && v.$__ != null && v._doc != null) {
+    if (includeExtraKeys) {
+      const extraKeys = {};
+      for (const key of Object.keys(v)) {
+        if (typeof key === 'symbol') {
+          continue;
+        }
+        if (key[0] === '$') {
+          continue;
+        }
+        if (keysToSkip.has(key)) {
+          continue;
+        }
+        extraKeys[key] = v[key];
+      }
+      return { ...v._doc, ...extraKeys };
+    }
+    return v._doc;
+  }
+
+  return v;
+};

node_modules/mongoose/lib/helpers/each.js

@@ -0,0 +1,25 @@
+'use strict';
+
+module.exports = function each(arr, cb, done) {
+  if (arr.length === 0) {
+    return done();
+  }
+
+  let remaining = arr.length;
+  let err = null;
+  for (const v of arr) {
+    cb(v, function(_err) {
+      if (err != null) {
+        return;
+      }
+      if (_err != null) {
+        err = _err;
+        return done(err);
+      }
+
+      if (--remaining <= 0) {
+        return done();
+      }
+    });
+  }
+};

node_modules/mongoose/lib/helpers/error/combinePathErrors.js

@@ -0,0 +1,22 @@
+'use strict';
+
+/*!
+ * ignore
+ */
+
+module.exports = function combinePathErrors(err) {
+  const keys = Object.keys(err.errors || {});
+  const len = keys.length;
+  const msgs = [];
+  let key;
+
+  for (let i = 0; i < len; ++i) {
+    key = keys[i];
+    if (err === err.errors[key]) {
+      continue;
+    }
+    msgs.push(key + ': ' + err.errors[key].message);
+  }
+
+  return msgs.join(', ');
+};

node_modules/mongoose/lib/helpers/firstKey.js

@@ -0,0 +1,8 @@
+'use strict';
+
+module.exports = function firstKey(obj) {
+  if (obj == null) {
+    return null;
+  }
+  return Object.keys(obj)[0];
+};

node_modules/mongoose/lib/helpers/get.js

@@ -0,0 +1,65 @@
+'use strict';
+
+/**
+ * Simplified lodash.get to work around the annoying null quirk. See:
+ * https://github.com/lodash/lodash/issues/3659
+ * @api private
+ */
+
+module.exports = function get(obj, path, def) {
+  let parts;
+  let isPathArray = false;
+  if (typeof path === 'string') {
+    if (path.indexOf('.') === -1) {
+      const _v = getProperty(obj, path);
+      if (_v == null) {
+        return def;
+      }
+      return _v;
+    }
+
+    parts = path.split('.');
+  } else {
+    isPathArray = true;
+    parts = path;
+
+    if (parts.length === 1) {
+      const _v = getProperty(obj, parts[0]);
+      if (_v == null) {
+        return def;
+      }
+      return _v;
+    }
+  }
+  let rest = path;
+  let cur = obj;
+  for (const part of parts) {
+    if (cur == null) {
+      return def;
+    }
+
+    // `lib/cast.js` depends on being able to get dotted paths in updates,
+    // like `{ $set: { 'a.b': 42 } }`
+    if (!isPathArray && cur[rest] != null) {
+      return cur[rest];
+    }
+
+    cur = getProperty(cur, part);
+
+    if (!isPathArray) {
+      rest = rest.substr(part.length + 1);
+    }
+  }
+
+  return cur == null ? def : cur;
+};
+
+function getProperty(obj, prop) {
+  if (obj == null) {
+    return obj;
+  }
+  if (obj instanceof Map) {
+    return obj.get(prop);
+  }
+  return obj[prop];
+}

node_modules/mongoose/lib/helpers/getConstructorName.js

@@ -0,0 +1,16 @@
+'use strict';
+
+/**
+ * If `val` is an object, returns constructor name, if possible. Otherwise returns undefined.
+ * @api private
+ */
+
+module.exports = function getConstructorName(val) {
+  if (val == null) {
+    return void 0;
+  }
+  if (typeof val.constructor !== 'function') {
+    return void 0;
+  }
+  return val.constructor.name;
+};

node_modules/mongoose/lib/helpers/getDefaultBulkwriteResult.js

@@ -0,0 +1,27 @@
+'use strict';
+function getDefaultBulkwriteResult() {
+  return {
+    result: {
+      ok: 1,
+      writeErrors: [],
+      writeConcernErrors: [],
+      insertedIds: [],
+      nInserted: 0,
+      nUpserted: 0,
+      nMatched: 0,
+      nModified: 0,
+      nRemoved: 0,
+      upserted: []
+    },
+    insertedCount: 0,
+    matchedCount: 0,
+    modifiedCount: 0,
+    deletedCount: 0,
+    upsertedCount: 0,
+    upsertedIds: {},
+    insertedIds: {},
+    n: 0
+  };
+}
+
+module.exports = getDefaultBulkwriteResult;

node_modules/mongoose/lib/helpers/getFunctionName.js

@@ -0,0 +1,10 @@
+'use strict';
+
+const functionNameRE = /^function\s*([^\s(]+)/;
+
+module.exports = function(fn) {
+  return (
+    fn.name ||
+    (fn.toString().trim().match(functionNameRE) || [])[1]
+  );
+};

node_modules/mongoose/lib/helpers/immediate.js

@@ -0,0 +1,16 @@
+/*!
+ * Centralize this so we can more easily work around issues with people
+ * stubbing out `process.nextTick()` in tests using sinon:
+ * https://github.com/sinonjs/lolex#automatically-incrementing-mocked-time
+ * See gh-6074
+ */
+
+'use strict';
+
+const nextTick = typeof process !== 'undefined' && typeof process.nextTick === 'function' ?
+  process.nextTick.bind(process) :
+  cb => setTimeout(cb, 0); // Fallback for browser build
+
+module.exports = function immediate(cb) {
+  return nextTick(cb);
+};

node_modules/mongoose/lib/helpers/indexes/applySchemaCollation.js

@@ -0,0 +1,13 @@
+'use strict';
+
+const isTextIndex = require('./isTextIndex');
+
+module.exports = function applySchemaCollation(indexKeys, indexOptions, schemaOptions) {
+  if (isTextIndex(indexKeys)) {
+    return;
+  }
+
+  if (schemaOptions.hasOwnProperty('collation') && !indexOptions.hasOwnProperty('collation')) {
+    indexOptions.collation = schemaOptions.collation;
+  }
+};

node_modules/mongoose/lib/helpers/indexes/decorateDiscriminatorIndexOptions.js

@@ -0,0 +1,14 @@
+'use strict';
+
+module.exports = function decorateDiscriminatorIndexOptions(schema, indexOptions) {
+  // If the model is a discriminator and has an index, add a
+  // partialFilterExpression by default so the index will only apply
+  // to that discriminator.
+  const discriminatorName = schema.discriminatorMapping && schema.discriminatorMapping.value;
+  if (discriminatorName && !('sparse' in indexOptions)) {
+    const discriminatorKey = schema.options.discriminatorKey;
+    indexOptions.partialFilterExpression = indexOptions.partialFilterExpression || {};
+    indexOptions.partialFilterExpression[discriminatorKey] = discriminatorName;
+  }
+  return indexOptions;
+};

node_modules/mongoose/lib/helpers/indexes/getRelatedIndexes.js

@@ -0,0 +1,59 @@
+'use strict';
+
+function getRelatedSchemaIndexes(model, schemaIndexes) {
+  return getRelatedIndexes({
+    baseModelName: model.baseModelName,
+    discriminatorMapping: model.schema.discriminatorMapping,
+    indexes: schemaIndexes,
+    indexesType: 'schema'
+  });
+}
+
+function getRelatedDBIndexes(model, dbIndexes) {
+  return getRelatedIndexes({
+    baseModelName: model.baseModelName,
+    discriminatorMapping: model.schema.discriminatorMapping,
+    indexes: dbIndexes,
+    indexesType: 'db'
+  });
+}
+
+module.exports = {
+  getRelatedSchemaIndexes,
+  getRelatedDBIndexes
+};
+
+function getRelatedIndexes({
+  baseModelName,
+  discriminatorMapping,
+  indexes,
+  indexesType
+}) {
+  const discriminatorKey = discriminatorMapping && discriminatorMapping.key;
+  const discriminatorValue = discriminatorMapping && discriminatorMapping.value;
+
+  if (!discriminatorKey) {
+    return indexes;
+  }
+
+  const isChildDiscriminatorModel = Boolean(baseModelName);
+  if (isChildDiscriminatorModel) {
+    return indexes.filter(index => {
+      const partialFilterExpression = getPartialFilterExpression(index, indexesType);
+      return partialFilterExpression && partialFilterExpression[discriminatorKey] === discriminatorValue;
+    });
+  }
+
+  return indexes.filter(index => {
+    const partialFilterExpression = getPartialFilterExpression(index, indexesType);
+    return !partialFilterExpression || !partialFilterExpression[discriminatorKey];
+  });
+}
+
+function getPartialFilterExpression(index, indexesType) {
+  if (indexesType === 'schema') {
+    const options = index[1];
+    return options && options.partialFilterExpression;
+  }
+  return index.partialFilterExpression;
+}

node_modules/mongoose/lib/helpers/indexes/isDefaultIdIndex.js

@@ -0,0 +1,18 @@
+'use strict';
+
+const get = require('../get');
+
+module.exports = function isDefaultIdIndex(index) {
+  if (Array.isArray(index)) {
+    // Mongoose syntax
+    const keys = Object.keys(index[0]);
+    return keys.length === 1 && keys[0] === '_id' && index[0]._id !== 'hashed';
+  }
+
+  if (typeof index !== 'object') {
+    return false;
+  }
+
+  const key = get(index, 'key', {});
+  return Object.keys(key).length === 1 && key.hasOwnProperty('_id');
+};

node_modules/mongoose/lib/helpers/indexes/isIndexEqual.js

@@ -0,0 +1,96 @@
+'use strict';
+
+const get = require('../get');
+const utils = require('../../utils');
+/**
+ * Given a Mongoose index definition (key + options objects) and a MongoDB server
+ * index definition, determine if the two indexes are equal.
+ *
+ * @param {Object} schemaIndexKeysObject the Mongoose index spec
+ * @param {Object} options the Mongoose index definition's options
+ * @param {Object} dbIndex the index in MongoDB as returned by `listIndexes()`
+ * @api private
+ */
+
+module.exports = function isIndexEqual(schemaIndexKeysObject, options, dbIndex) {
+  // Special case: text indexes have a special format in the db. For example,
+  // `{ name: 'text' }` becomes:
+  // {
+  //   v: 2,
+  //   key: { _fts: 'text', _ftsx: 1 },
+  //   name: 'name_text',
+  //   ns: 'test.tests',
+  //   background: true,
+  //   weights: { name: 1 },
+  //   default_language: 'english',
+  //   language_override: 'language',
+  //   textIndexVersion: 3
+  // }
+  if (dbIndex.textIndexVersion != null) {
+    delete dbIndex.key._fts;
+    delete dbIndex.key._ftsx;
+    const weights = { ...dbIndex.weights, ...dbIndex.key };
+    if (Object.keys(weights).length !== Object.keys(schemaIndexKeysObject).length) {
+      return false;
+    }
+    for (const prop of Object.keys(weights)) {
+      if (!(prop in schemaIndexKeysObject)) {
+        return false;
+      }
+      const weight = weights[prop];
+      if (weight !== get(options, 'weights.' + prop) && !(weight === 1 && get(options, 'weights.' + prop) == null)) {
+        return false;
+      }
+    }
+
+    if (options['default_language'] !== dbIndex['default_language']) {
+      return dbIndex['default_language'] === 'english' && options['default_language'] == null;
+    }
+
+    return true;
+  }
+
+  const optionKeys = [
+    'unique',
+    'partialFilterExpression',
+    'sparse',
+    'expireAfterSeconds',
+    'collation'
+  ];
+  for (const key of optionKeys) {
+    if (!(key in options) && !(key in dbIndex)) {
+      continue;
+    }
+    if (key === 'collation') {
+      if (options[key] == null || dbIndex[key] == null) {
+        return options[key] == null && dbIndex[key] == null;
+      }
+      const definedKeys = Object.keys(options.collation);
+      const schemaCollation = options.collation;
+      const dbCollation = dbIndex.collation;
+      for (const opt of definedKeys) {
+        if (get(schemaCollation, opt) !== get(dbCollation, opt)) {
+          return false;
+        }
+      }
+    } else if (!utils.deepEqual(options[key], dbIndex[key])) {
+      return false;
+    }
+  }
+
+  const schemaIndexKeys = Object.keys(schemaIndexKeysObject);
+  const dbIndexKeys = Object.keys(dbIndex.key);
+  if (schemaIndexKeys.length !== dbIndexKeys.length) {
+    return false;
+  }
+  for (let i = 0; i < schemaIndexKeys.length; ++i) {
+    if (schemaIndexKeys[i] !== dbIndexKeys[i]) {
+      return false;
+    }
+    if (!utils.deepEqual(schemaIndexKeysObject[schemaIndexKeys[i]], dbIndex.key[dbIndexKeys[i]])) {
+      return false;
+    }
+  }
+
+  return true;
+};

node_modules/mongoose/lib/helpers/indexes/isTextIndex.js

@@ -0,0 +1,16 @@
+'use strict';
+
+/**
+ * Returns `true` if the given index options have a `text` option.
+ */
+
+module.exports = function isTextIndex(indexKeys) {
+  let isTextIndex = false;
+  for (const key of Object.keys(indexKeys)) {
+    if (indexKeys[key] === 'text') {
+      isTextIndex = true;
+    }
+  }
+
+  return isTextIndex;
+};

node_modules/mongoose/lib/helpers/isAsyncFunction.js

@@ -0,0 +1,9 @@
+'use strict';
+
+module.exports = function isAsyncFunction(v) {
+  return (
+    typeof v === 'function' &&
+    v.constructor &&
+    v.constructor.name === 'AsyncFunction'
+  );
+};

node_modules/mongoose/lib/helpers/isBsonType.js

@@ -0,0 +1,16 @@
+'use strict';
+
+/**
+ * Get the bson type, if it exists
+ * @api private
+ */
+
+function isBsonType(obj, typename) {
+  return (
+    typeof obj === 'object' &&
+    obj !== null &&
+    obj._bsontype === typename
+  );
+}
+
+module.exports = isBsonType;

node_modules/mongoose/lib/helpers/isMongooseObject.js

@@ -0,0 +1,22 @@
+'use strict';
+
+const isMongooseArray = require('../types/array/isMongooseArray').isMongooseArray;
+/**
+ * Returns if `v` is a mongoose object that has a `toObject()` method we can use.
+ *
+ * This is for compatibility with libs like Date.js which do foolish things to Natives.
+ *
+ * @param {Any} v
+ * @api private
+ */
+
+module.exports = function(v) {
+  return (
+    v != null && (
+      isMongooseArray(v) || // Array or Document Array
+      v.$__ != null || // Document
+      v.isMongooseBuffer || // Buffer
+      v.$isMongooseMap // Map
+    )
+  );
+};

node_modules/mongoose/lib/helpers/isObject.js

@@ -0,0 +1,16 @@
+'use strict';
+
+/**
+ * Determines if `arg` is an object.
+ *
+ * @param {Object|Array|String|Function|RegExp|any} arg
+ * @api private
+ * @return {Boolean}
+ */
+
+module.exports = function(arg) {
+  return (
+    Buffer.isBuffer(arg) ||
+    Object.prototype.toString.call(arg) === '[object Object]'
+  );
+};

node_modules/mongoose/lib/helpers/isPOJO.js

@@ -0,0 +1,12 @@
+'use strict';
+
+module.exports = function isPOJO(arg) {
+  if (arg == null || typeof arg !== 'object') {
+    return false;
+  }
+  const proto = Object.getPrototypeOf(arg);
+  // Prototype may be null if you used `Object.create(null)`
+  // Checking `proto`'s constructor is safe because `getPrototypeOf()`
+  // explicitly crosses the boundary from object data to object metadata
+  return !proto || proto.constructor.name === 'Object';
+};

node_modules/mongoose/lib/helpers/isPromise.js

@@ -0,0 +1,6 @@
+'use strict';
+function isPromise(val) {
+  return !!val && (typeof val === 'object' || typeof val === 'function') && typeof val.then === 'function';
+}
+
+module.exports = isPromise;

node_modules/mongoose/lib/helpers/isSimpleValidator.js

@@ -0,0 +1,22 @@
+'use strict';
+
+/**
+ * Determines if `arg` is a flat object.
+ *
+ * @param {Object|Array|String|Function|RegExp|any} arg
+ * @api private
+ * @return {Boolean}
+ */
+
+module.exports = function isSimpleValidator(obj) {
+  const keys = Object.keys(obj);
+  let result = true;
+  for (let i = 0, len = keys.length; i < len; ++i) {
+    if (typeof obj[keys[i]] === 'object' && obj[keys[i]] !== null) {
+      result = false;
+      break;
+    }
+  }
+
+  return result;
+};

node_modules/mongoose/lib/helpers/model/applyDefaultsToPOJO.js

@@ -0,0 +1,52 @@
+'use strict';
+
+module.exports = function applyDefaultsToPOJO(doc, schema) {
+  const paths = Object.keys(schema.paths);
+  const plen = paths.length;
+
+  for (let i = 0; i < plen; ++i) {
+    let curPath = '';
+    const p = paths[i];
+
+    const type = schema.paths[p];
+    const path = type.splitPath();
+    const len = path.length;
+    let doc_ = doc;
+    for (let j = 0; j < len; ++j) {
+      if (doc_ == null) {
+        break;
+      }
+
+      const piece = path[j];
+      curPath += (!curPath.length ? '' : '.') + piece;
+
+      if (j === len - 1) {
+        if (typeof doc_[piece] !== 'undefined') {
+          if (type.$isSingleNested) {
+            applyDefaultsToPOJO(doc_[piece], type.caster.schema);
+          } else if (type.$isMongooseDocumentArray && Array.isArray(doc_[piece])) {
+            doc_[piece].forEach(el => applyDefaultsToPOJO(el, type.schema));
+          }
+
+          break;
+        }
+
+        const def = type.getDefault(doc, false, { skipCast: true });
+        if (typeof def !== 'undefined') {
+          doc_[piece] = def;
+
+          if (type.$isSingleNested) {
+            applyDefaultsToPOJO(def, type.caster.schema);
+          } else if (type.$isMongooseDocumentArray && Array.isArray(def)) {
+            def.forEach(el => applyDefaultsToPOJO(el, type.schema));
+          }
+        }
+      } else {
+        if (doc_[piece] == null) {
+          doc_[piece] = {};
+        }
+        doc_ = doc_[piece];
+      }
+    }
+  }
+};

node_modules/mongoose/lib/helpers/model/applyHooks.js

@@ -0,0 +1,149 @@
+'use strict';
+
+const symbols = require('../../schema/symbols');
+const promiseOrCallback = require('../promiseOrCallback');
+
+/*!
+ * ignore
+ */
+
+module.exports = applyHooks;
+
+/*!
+ * ignore
+ */
+
+applyHooks.middlewareFunctions = [
+  'deleteOne',
+  'save',
+  'validate',
+  'remove',
+  'updateOne',
+  'init'
+];
+
+/*!
+ * ignore
+ */
+
+const alreadyHookedFunctions = new Set(applyHooks.middlewareFunctions.flatMap(fn => ([fn, `$__${fn}`])));
+
+/**
+ * Register hooks for this model
+ *
+ * @param {Model} model
+ * @param {Schema} schema
+ * @param {Object} options
+ * @api private
+ */
+
+function applyHooks(model, schema, options) {
+  options = options || {};
+
+  const kareemOptions = {
+    useErrorHandlers: true,
+    numCallbackParams: 1,
+    nullResultByDefault: true,
+    contextParameter: true
+  };
+  const objToDecorate = options.decorateDoc ? model : model.prototype;
+
+  model.$appliedHooks = true;
+  for (const key of Object.keys(schema.paths)) {
+    const type = schema.paths[key];
+    let childModel = null;
+    if (type.$isSingleNested) {
+      childModel = type.caster;
+    } else if (type.$isMongooseDocumentArray) {
+      childModel = type.Constructor;
+    } else {
+      continue;
+    }
+
+    if (childModel.$appliedHooks) {
+      continue;
+    }
+
+    applyHooks(childModel, type.schema, options);
+    if (childModel.discriminators != null) {
+      const keys = Object.keys(childModel.discriminators);
+      for (const key of keys) {
+        applyHooks(childModel.discriminators[key],
+          childModel.discriminators[key].schema, options);
+      }
+    }
+  }
+
+  // Built-in hooks rely on hooking internal functions in order to support
+  // promises and make it so that `doc.save.toString()` provides meaningful
+  // information.
+
+  const middleware = schema.s.hooks.
+    filter(hook => {
+      if (hook.name === 'updateOne' || hook.name === 'deleteOne') {
+        return !!hook['document'];
+      }
+      if (hook.name === 'remove' || hook.name === 'init') {
+        return hook['document'] == null || !!hook['document'];
+      }
+      if (hook.query != null || hook.document != null) {
+        return hook.document !== false;
+      }
+      return true;
+    }).
+    filter(hook => {
+      // If user has overwritten the method, don't apply built-in middleware
+      if (schema.methods[hook.name]) {
+        return !hook.fn[symbols.builtInMiddleware];
+      }
+
+      return true;
+    });
+
+  model._middleware = middleware;
+
+  objToDecorate.$__originalValidate = objToDecorate.$__originalValidate || objToDecorate.$__validate;
+
+  for (const method of ['save', 'validate', 'remove', 'deleteOne']) {
+    const toWrap = method === 'validate' ? '$__originalValidate' : `$__${method}`;
+    const wrapped = middleware.
+      createWrapper(method, objToDecorate[toWrap], null, kareemOptions);
+    objToDecorate[`$__${method}`] = wrapped;
+  }
+  objToDecorate.$__init = middleware.
+    createWrapperSync('init', objToDecorate.$__init, null, kareemOptions);
+
+  // Support hooks for custom methods
+  const customMethods = Object.keys(schema.methods);
+  const customMethodOptions = Object.assign({}, kareemOptions, {
+    // Only use `checkForPromise` for custom methods, because mongoose
+    // query thunks are not as consistent as I would like about returning
+    // a nullish value rather than the query. If a query thunk returns
+    // a query, `checkForPromise` causes infinite recursion
+    checkForPromise: true
+  });
+  for (const method of customMethods) {
+    if (alreadyHookedFunctions.has(method)) {
+      continue;
+    }
+    if (!middleware.hasHooks(method)) {
+      // Don't wrap if there are no hooks for the custom method to avoid
+      // surprises. Also, `createWrapper()` enforces consistent async,
+      // so wrapping a sync method would break it.
+      continue;
+    }
+    const originalMethod = objToDecorate[method];
+    objToDecorate[method] = function() {
+      const args = Array.prototype.slice.call(arguments);
+      const cb = args.slice(-1).pop();
+      const argsWithoutCallback = typeof cb === 'function' ?
+        args.slice(0, args.length - 1) : args;
+      return promiseOrCallback(cb, callback => {
+        return this[`$__${method}`].apply(this,
+          argsWithoutCallback.concat([callback]));
+      }, model.events);
+    };
+    objToDecorate[`$__${method}`] = middleware.
+      createWrapper(method, originalMethod, null, customMethodOptions);
+  }
+}

node_modules/mongoose/lib/helpers/model/applyMethods.js

@@ -0,0 +1,70 @@
+'use strict';
+
+const get = require('../get');
+const utils = require('../../utils');
+
+/**
+ * Register methods for this model
+ *
+ * @param {Model} model
+ * @param {Schema} schema
+ * @api private
+ */
+
+module.exports = function applyMethods(model, schema) {
+  const Model = require('../../model');
+
+  function apply(method, schema) {
+    Object.defineProperty(model.prototype, method, {
+      get: function() {
+        const h = {};
+        for (const k in schema.methods[method]) {
+          h[k] = schema.methods[method][k].bind(this);
+        }
+        return h;
+      },
+      configurable: true
+    });
+  }
+  for (const method of Object.keys(schema.methods)) {
+    const fn = schema.methods[method];
+    if (schema.tree.hasOwnProperty(method)) {
+      throw new Error('You have a method and a property in your schema both ' +
+        'named "' + method + '"');
+    }
+
+    // Avoid making custom methods if user sets a method to itself, e.g.
+    // `schema.method(save, Document.prototype.save)`. Can happen when
+    // calling `loadClass()` with a class that `extends Document`. See gh-12254
+    if (typeof fn === 'function' &&
+        Model.prototype[method] === fn) {
+      delete schema.methods[method];
+      continue;
+    }
+
+    if (schema.reserved[method] &&
+        !get(schema, `methodOptions.${method}.suppressWarning`, false)) {
+      utils.warn(`mongoose: the method name "${method}" is used by mongoose ` +
+        'internally, overwriting it may cause bugs. If you\'re sure you know ' +
+        'what you\'re doing, you can suppress this error by using ' +
+        `\`schema.method('${method}', fn, { suppressWarning: true })\`.`);
+    }
+    if (typeof fn === 'function') {
+      model.prototype[method] = fn;
+    } else {
+      apply(method, schema);
+    }
+  }
+
+  // Recursively call `applyMethods()` on child schemas
+  model.$appliedMethods = true;
+  for (const key of Object.keys(schema.paths)) {
+    const type = schema.paths[key];
+    if (type.$isSingleNested && !type.caster.$appliedMethods) {
+      applyMethods(type.caster, type.schema);
+    }
+    if (type.$isMongooseDocumentArray && !type.Constructor.$appliedMethods) {
+      applyMethods(type.Constructor, type.schema);
+    }
+  }
+};

node_modules/mongoose/lib/helpers/model/applyStaticHooks.js

@@ -0,0 +1,71 @@
+'use strict';
+
+const middlewareFunctions = require('../query/applyQueryMiddleware').middlewareFunctions;
+const promiseOrCallback = require('../promiseOrCallback');
+
+module.exports = function applyStaticHooks(model, hooks, statics) {
+  const kareemOptions = {
+    useErrorHandlers: true,
+    numCallbackParams: 1
+  };
+
+  hooks = hooks.filter(hook => {
+    // If the custom static overwrites an existing query middleware, don't apply
+    // middleware to it by default. This avoids a potential backwards breaking
+    // change with plugins like `mongoose-delete` that use statics to overwrite
+    // built-in Mongoose functions.
+    if (middlewareFunctions.indexOf(hook.name) !== -1) {
+      return !!hook.model;
+    }
+    return hook.model !== false;
+  });
+
+  model.$__insertMany = hooks.createWrapper('insertMany',
+    model.$__insertMany, model, kareemOptions);
+
+  for (const key of Object.keys(statics)) {
+    if (hooks.hasHooks(key)) {
+      const original = model[key];
+
+      model[key] = function() {
+        const numArgs = arguments.length;
+        const lastArg = numArgs > 0 ? arguments[numArgs - 1] : null;
+        const cb = typeof lastArg === 'function' ? lastArg : null;
+        const args = Array.prototype.slice.
+          call(arguments, 0, cb == null ? numArgs : numArgs - 1);
+        // Special case: can't use `Kareem#wrap()` because it doesn't currently
+        // support wrapped functions that return a promise.
+        return promiseOrCallback(cb, callback => {
+          hooks.execPre(key, model, args, function(err) {
+            if (err != null) {
+              return callback(err);
+            }
+
+            let postCalled = 0;
+            const ret = original.apply(model, args.concat(post));
+            if (ret != null && typeof ret.then === 'function') {
+              ret.then(res => post(null, res), err => post(err));
+            }
+
+            function post(error, res) {
+              if (postCalled++ > 0) {
+                return;
+              }
+
+              if (error != null) {
+                return callback(error);
+              }
+
+              hooks.execPost(key, model, [res], function(error) {
+                if (error != null) {
+                  return callback(error);
+                }
+                callback(null, res);
+              });
+            }
+          });
+        }, model.events);
+      };
+    }
+  }
+};

node_modules/mongoose/lib/helpers/model/applyStatics.js

@@ -0,0 +1,13 @@
+'use strict';
+
+/**
+ * Register statics for this model
+ * @param {Model} model
+ * @param {Schema} schema
+ * @api private
+ */
+module.exports = function applyStatics(model, schema) {
+  for (const i in schema.statics) {
+    model[i] = schema.statics[i];
+  }
+};

node_modules/mongoose/lib/helpers/model/castBulkWrite.js

@@ -0,0 +1,240 @@
+'use strict';
+
+const getDiscriminatorByValue = require('../../helpers/discriminator/getDiscriminatorByValue');
+const applyTimestampsToChildren = require('../update/applyTimestampsToChildren');
+const applyTimestampsToUpdate = require('../update/applyTimestampsToUpdate');
+const cast = require('../../cast');
+const castUpdate = require('../query/castUpdate');
+const setDefaultsOnInsert = require('../setDefaultsOnInsert');
+
+/**
+ * Given a model and a bulkWrite op, return a thunk that handles casting and
+ * validating the individual op.
+ * @param {Model} originalModel
+ * @param {Object} op
+ * @param {Object} [options]
+ * @api private
+ */
+
+module.exports = function castBulkWrite(originalModel, op, options) {
+  const now = originalModel.base.now();
+
+  if (op['insertOne']) {
+    return (callback) => {
+      const model = decideModelByObject(originalModel, op['insertOne']['document']);
+
+      const doc = new model(op['insertOne']['document']);
+      if (model.schema.options.timestamps && options.timestamps !== false) {
+        doc.initializeTimestamps();
+      }
+      if (options.session != null) {
+        doc.$session(options.session);
+      }
+      op['insertOne']['document'] = doc;
+
+      if (options.skipValidation || op['insertOne'].skipValidation) {
+        callback(null);
+        return;
+      }
+
+      op['insertOne']['document'].$validate().then(
+        () => { callback(null); },
+        err => { callback(err, null); }
+      );
+    };
+  } else if (op['updateOne']) {
+    return (callback) => {
+      try {
+        if (!op['updateOne']['filter']) {
+          throw new Error('Must provide a filter object.');
+        }
+        if (!op['updateOne']['update']) {
+          throw new Error('Must provide an update object.');
+        }
+
+        const model = decideModelByObject(originalModel, op['updateOne']['filter']);
+        const schema = model.schema;
+        const strict = options.strict != null ? options.strict : model.schema.options.strict;
+
+        _addDiscriminatorToObject(schema, op['updateOne']['filter']);
+
+        if (model.schema.$timestamps != null && op['updateOne'].timestamps !== false) {
+          const createdAt = model.schema.$timestamps.createdAt;
+          const updatedAt = model.schema.$timestamps.updatedAt;
+          applyTimestampsToUpdate(now, createdAt, updatedAt, op['updateOne']['update'], {});
+        }
+
+        applyTimestampsToChildren(now, op['updateOne']['update'], model.schema);
+
+        if (op['updateOne'].setDefaultsOnInsert !== false) {
+          setDefaultsOnInsert(op['updateOne']['filter'], model.schema, op['updateOne']['update'], {
+            setDefaultsOnInsert: true,
+            upsert: op['updateOne'].upsert
+          });
+        }
+
+        op['updateOne']['filter'] = cast(model.schema, op['updateOne']['filter'], {
+          strict: strict,
+          upsert: op['updateOne'].upsert
+        });
+
+        op['updateOne']['update'] = castUpdate(model.schema, op['updateOne']['update'], {
+          strict: strict,
+          overwrite: false,
+          upsert: op['updateOne'].upsert
+        }, model, op['updateOne']['filter']);
+      } catch (error) {
+        return callback(error, null);
+      }
+
+      callback(null);
+    };
+  } else if (op['updateMany']) {
+    return (callback) => {
+      try {
+        if (!op['updateMany']['filter']) {
+          throw new Error('Must provide a filter object.');
+        }
+        if (!op['updateMany']['update']) {
+          throw new Error('Must provide an update object.');
+        }
+
+        const model = decideModelByObject(originalModel, op['updateMany']['filter']);
+        const schema = model.schema;
+        const strict = options.strict != null ? options.strict : model.schema.options.strict;
+
+        if (op['updateMany'].setDefaultsOnInsert !== false) {
+          setDefaultsOnInsert(op['updateMany']['filter'], model.schema, op['updateMany']['update'], {
+            setDefaultsOnInsert: true,
+            upsert: op['updateMany'].upsert
+          });
+        }
+
+        if (model.schema.$timestamps != null && op['updateMany'].timestamps !== false) {
+          const createdAt = model.schema.$timestamps.createdAt;
+          const updatedAt = model.schema.$timestamps.updatedAt;
+          applyTimestampsToUpdate(now, createdAt, updatedAt, op['updateMany']['update'], {});
+        }
+
+        applyTimestampsToChildren(now, op['updateMany']['update'], model.schema);
+
+        _addDiscriminatorToObject(schema, op['updateMany']['filter']);
+
+        op['updateMany']['filter'] = cast(model.schema, op['updateMany']['filter'], {
+          strict: strict,
+          upsert: op['updateMany'].upsert
+        });
+
+        op['updateMany']['update'] = castUpdate(model.schema, op['updateMany']['update'], {
+          strict: strict,
+          overwrite: false,
+          upsert: op['updateMany'].upsert
+        }, model, op['updateMany']['filter']);
+      } catch (error) {
+        return callback(error, null);
+      }
+
+      callback(null);
+    };
+  } else if (op['replaceOne']) {
+    return (callback) => {
+      const model = decideModelByObject(originalModel, op['replaceOne']['filter']);
+      const schema = model.schema;
+      const strict = options.strict != null ? options.strict : model.schema.options.strict;
+
+      _addDiscriminatorToObject(schema, op['replaceOne']['filter']);
+      try {
+        op['replaceOne']['filter'] = cast(model.schema, op['replaceOne']['filter'], {
+          strict: strict,
+          upsert: op['replaceOne'].upsert
+        });
+      } catch (error) {
+        return callback(error, null);
+      }
+
+      // set `skipId`, otherwise we get "_id field cannot be changed"
+      const doc = new model(op['replaceOne']['replacement'], strict, true);
+      if (model.schema.options.timestamps) {
+        doc.initializeTimestamps();
+      }
+      if (options.session != null) {
+        doc.$session(options.session);
+      }
+      op['replaceOne']['replacement'] = doc;
+
+      if (options.skipValidation || op['replaceOne'].skipValidation) {
+        op['replaceOne']['replacement'] = op['replaceOne']['replacement'].toBSON();
+        callback(null);
+        return;
+      }
+
+      op['replaceOne']['replacement'].$validate().then(
+        () => {
+          op['replaceOne']['replacement'] = op['replaceOne']['replacement'].toBSON();
+          callback(null);
+        },
+        error => {
+          callback(error, null);
+        }
+      );
+    };
+  } else if (op['deleteOne']) {
+    return (callback) => {
+      const model = decideModelByObject(originalModel, op['deleteOne']['filter']);
+      const schema = model.schema;
+
+      _addDiscriminatorToObject(schema, op['deleteOne']['filter']);
+
+      try {
+        op['deleteOne']['filter'] = cast(model.schema,
+          op['deleteOne']['filter']);
+      } catch (error) {
+        return callback(error, null);
+      }
+
+      callback(null);
+    };
+  } else if (op['deleteMany']) {
+    return (callback) => {
+      const model = decideModelByObject(originalModel, op['deleteMany']['filter']);
+      const schema = model.schema;
+
+      _addDiscriminatorToObject(schema, op['deleteMany']['filter']);
+
+      try {
+        op['deleteMany']['filter'] = cast(model.schema,
+          op['deleteMany']['filter']);
+      } catch (error) {
+        return callback(error, null);
+      }
+
+      callback(null);
+    };
+  } else {
+    return (callback) => {
+      callback(new Error('Invalid op passed to `bulkWrite()`'), null);
+    };
+  }
+};
+
+function _addDiscriminatorToObject(schema, obj) {
+  if (schema == null) {
+    return;
+  }
+  if (schema.discriminatorMapping && !schema.discriminatorMapping.isRoot) {
+    obj[schema.discriminatorMapping.key] = schema.discriminatorMapping.value;
+  }
+}
+
+/**
+ * gets discriminator model if discriminator key is present in object
+ * @api private
+ */
+
+function decideModelByObject(model, object) {
+  const discriminatorKey = model.schema.options.discriminatorKey;
+  if (object != null && object.hasOwnProperty(discriminatorKey)) {
+    model = getDiscriminatorByValue(model.discriminators, object[discriminatorKey]) || model;
+  }
+  return model;
+}

node_modules/mongoose/lib/helpers/model/discriminator.js

@@ -0,0 +1,213 @@
+'use strict';
+
+const Mixed = require('../../schema/mixed');
+const applyBuiltinPlugins = require('../schema/applyBuiltinPlugins');
+const clone = require('../clone');
+const defineKey = require('../document/compile').defineKey;
+const get = require('../get');
+const utils = require('../../utils');
+const mergeDiscriminatorSchema = require('../../helpers/discriminator/mergeDiscriminatorSchema');
+
+const CUSTOMIZABLE_DISCRIMINATOR_OPTIONS = {
+  toJSON: true,
+  toObject: true,
+  _id: true,
+  id: true,
+  virtuals: true,
+  methods: true
+};
+
+/*!
+ * ignore
+ */
+
+module.exports = function discriminator(model, name, schema, tiedValue, applyPlugins, mergeHooks) {
+  if (!(schema && schema.instanceOfSchema)) {
+    throw new Error('You must pass a valid discriminator Schema');
+  }
+
+  mergeHooks = mergeHooks == null ? true : mergeHooks;
+
+  if (model.schema.discriminatorMapping &&
+      !model.schema.discriminatorMapping.isRoot) {
+    throw new Error('Discriminator "' + name +
+        '" can only be a discriminator of the root model');
+  }
+
+  if (applyPlugins) {
+    const applyPluginsToDiscriminators = get(model.base,
+      'options.applyPluginsToDiscriminators', false) || !mergeHooks;
+    // Even if `applyPluginsToDiscriminators` isn't set, we should still apply
+    // global plugins to schemas embedded in the discriminator schema (gh-7370)
+    model.base._applyPlugins(schema, {
+      skipTopLevel: !applyPluginsToDiscriminators
+    });
+  } else if (!mergeHooks) {
+    applyBuiltinPlugins(schema);
+  }
+
+  const key = model.schema.options.discriminatorKey;
+
+  const existingPath = model.schema.path(key);
+  if (existingPath != null) {
+    if (!utils.hasUserDefinedProperty(existingPath.options, 'select')) {
+      existingPath.options.select = true;
+    }
+    existingPath.options.$skipDiscriminatorCheck = true;
+  } else {
+    const baseSchemaAddition = {};
+    baseSchemaAddition[key] = {
+      default: void 0,
+      select: true,
+      $skipDiscriminatorCheck: true
+    };
+    baseSchemaAddition[key][model.schema.options.typeKey] = String;
+    model.schema.add(baseSchemaAddition);
+    defineKey({
+      prop: key,
+      prototype: model.prototype,
+      options: model.schema.options
+    });
+  }
+
+  if (schema.path(key) && schema.path(key).options.$skipDiscriminatorCheck !== true) {
+    throw new Error('Discriminator "' + name +
+        '" cannot have field with name "' + key + '"');
+  }
+
+  let value = name;
+  if ((typeof tiedValue === 'string' && tiedValue.length) || tiedValue != null) {
+    value = tiedValue;
+  }
+
+  function merge(schema, baseSchema) {
+    // Retain original schema before merging base schema
+    schema._baseSchema = baseSchema;
+    if (baseSchema.paths._id &&
+        baseSchema.paths._id.options &&
+        !baseSchema.paths._id.options.auto) {
+      schema.remove('_id');
+    }
+
+    // Find conflicting paths: if something is a path in the base schema
+    // and a nested path in the child schema, overwrite the base schema path.
+    // See gh-6076
+    const baseSchemaPaths = Object.keys(baseSchema.paths);
+    const conflictingPaths = [];
+
+    for (const path of baseSchemaPaths) {
+      if (schema.nested[path]) {
+        conflictingPaths.push(path);
+        continue;
+      }
+
+      if (path.indexOf('.') === -1) {
+        continue;
+      }
+      const sp = path.split('.').slice(0, -1);
+      let cur = '';
+      for (const piece of sp) {
+        cur += (cur.length ? '.' : '') + piece;
+        if (schema.paths[cur] instanceof Mixed ||
+            schema.singleNestedPaths[cur] instanceof Mixed) {
+          conflictingPaths.push(path);
+        }
+      }
+    }
+
+    mergeDiscriminatorSchema(schema, baseSchema);
+
+    // Clean up conflicting paths _after_ merging re: gh-6076
+    for (const conflictingPath of conflictingPaths) {
+      delete schema.paths[conflictingPath];
+    }
+
+    // Rebuild schema models because schemas may have been merged re: #7884
+    schema.childSchemas.forEach(obj => {
+      obj.model.prototype.$__setSchema(obj.schema);
+    });
+
+    const obj = {};
+    obj[key] = {
+      default: value,
+      select: true,
+      set: function(newName) {
+        if (newName === value || (Array.isArray(value) && utils.deepEqual(newName, value))) {
+          return value;
+        }
+        throw new Error('Can\'t set discriminator key "' + key + '"');
+      },
+      $skipDiscriminatorCheck: true
+    };
+    obj[key][schema.options.typeKey] = existingPath ? existingPath.options[schema.options.typeKey] : String;
+    schema.add(obj);
+
+    schema.discriminatorMapping = { key: key, value: value, isRoot: false };
+
+    if (baseSchema.options.collection) {
+      schema.options.collection = baseSchema.options.collection;
+    }
+    const toJSON = schema.options.toJSON;
+    const toObject = schema.options.toObject;
+    const _id = schema.options._id;
+    const id = schema.options.id;
+
+    const keys = Object.keys(schema.options);
+    schema.options.discriminatorKey = baseSchema.options.discriminatorKey;
+    const userProvidedOptions = schema._userProvidedOptions;
+    for (const _key of keys) {
+      if (!CUSTOMIZABLE_DISCRIMINATOR_OPTIONS[_key]) {
+        // Use `schema.options` in `deepEqual()` because of `discriminatorKey`
+        // set above. We don't allow customizing discriminator key, always
+        // overwrite. See gh-9238
+        if (_key in userProvidedOptions && !utils.deepEqual(schema.options[_key], baseSchema.options[_key])) {
+          throw new Error('Can\'t customize discriminator option ' + _key +
+            ' (can only modify ' +
+            Object.keys(CUSTOMIZABLE_DISCRIMINATOR_OPTIONS).join(', ') +
+            ')');
+        }
+      }
+    }
+    schema.options = clone(baseSchema.options);
+
+    for (const _key of Object.keys(userProvidedOptions)) {
+      schema.options[_key] = userProvidedOptions[_key];
+    }
+    if (toJSON) schema.options.toJSON = toJSON;
+    if (toObject) schema.options.toObject = toObject;
+    if (typeof _id !== 'undefined') {
+      schema.options._id = _id;
+    }
+    schema.options.id = id;
+    if (mergeHooks) {
+      schema.s.hooks = model.schema.s.hooks.merge(schema.s.hooks);
+    }
+    if (applyPlugins) {
+      schema.plugins = Array.prototype.slice.call(baseSchema.plugins);
+    }
+    schema.callQueue = baseSchema.callQueue.concat(schema.callQueue);
+    delete schema._requiredpaths; // reset just in case Schema#requiredPaths() was called on either schema
+  }
+
+  // merges base schema into new discriminator schema and sets new type field.
+  merge(schema, model.schema);
+
+  if (!model.discriminators) {
+    model.discriminators = {};
+  }
+
+  if (!model.schema.discriminatorMapping) {
+    model.schema.discriminatorMapping = { key: key, value: null, isRoot: true };
+  }
+  if (!model.schema.discriminators) {
+    model.schema.discriminators = {};
+  }
+
+  model.schema.discriminators[name] = schema;
+
+  if (model.discriminators[name] && !schema.options.overwriteModels) {
+    throw new Error('Discriminator with name "' + name + '" already exists');
+  }
+
+  return schema;
+};

node_modules/mongoose/lib/helpers/model/pushNestedArrayPaths.js

@@ -0,0 +1,15 @@
+'use strict';
+
+module.exports = function pushNestedArrayPaths(paths, nestedArray, path) {
+  if (nestedArray == null) {
+    return;
+  }
+
+  for (let i = 0; i < nestedArray.length; ++i) {
+    if (Array.isArray(nestedArray[i])) {
+      pushNestedArrayPaths(paths, nestedArray[i], path + '.' + i);
+    } else {
+      paths.push(path + '.' + i);
+    }
+  }
+};

node_modules/mongoose/lib/helpers/once.js

@@ -0,0 +1,12 @@
+'use strict';
+
+module.exports = function once(fn) {
+  let called = false;
+  return function() {
+    if (called) {
+      return;
+    }
+    called = true;
+    return fn.apply(null, arguments);
+  };
+};

node_modules/mongoose/lib/helpers/parallelLimit.js

@@ -0,0 +1,55 @@
+'use strict';
+
+module.exports = parallelLimit;
+
+/*!
+ * ignore
+ */
+
+function parallelLimit(fns, limit, callback) {
+  let numInProgress = 0;
+  let numFinished = 0;
+  let error = null;
+
+  if (limit <= 0) {
+    throw new Error('Limit must be positive');
+  }
+
+  if (fns.length === 0) {
+    return callback(null, []);
+  }
+
+  for (let i = 0; i < fns.length && i < limit; ++i) {
+    _start();
+  }
+
+  function _start() {
+    fns[numFinished + numInProgress](_done(numFinished + numInProgress));
+    ++numInProgress;
+  }
+
+  const results = [];
+
+  function _done(index) {
+    return (err, res) => {
+      --numInProgress;
+      ++numFinished;
+
+      if (error != null) {
+        return;
+      }
+      if (err != null) {
+        error = err;
+        return callback(error);
+      }
+
+      results[index] = res;
+
+      if (numFinished === fns.length) {
+        return callback(null, results);
+      } else if (numFinished + numInProgress < fns.length) {
+        _start();
+      }
+    };
+  }
+}

node_modules/mongoose/lib/helpers/path/flattenObjectWithDottedPaths.js

@@ -0,0 +1,39 @@
+'use strict';
+
+const MongooseError = require('../../error/mongooseError');
+const isMongooseObject = require('../isMongooseObject');
+const setDottedPath = require('../path/setDottedPath');
+const util = require('util');
+
+/**
+ * Given an object that may contain dotted paths, flatten the paths out.
+ * For example: `flattenObjectWithDottedPaths({ a: { 'b.c': 42 } })` => `{ a: { b: { c: 42 } } }`
+ */
+
+module.exports = function flattenObjectWithDottedPaths(obj) {
+  if (obj == null || typeof obj !== 'object' || Array.isArray(obj)) {
+    return;
+  }
+  // Avoid Mongoose docs, like docs and maps, because these may cause infinite recursion
+  if (isMongooseObject(obj)) {
+    return;
+  }
+  const keys = Object.keys(obj);
+  for (const key of keys) {
+    const val = obj[key];
+    if (key.indexOf('.') !== -1) {
+      try {
+        delete obj[key];
+        setDottedPath(obj, key, val);
+      } catch (err) {
+        if (!(err instanceof TypeError)) {
+          throw err;
+        }
+        throw new MongooseError(`Conflicting dotted paths when setting document path, key: "${key}", value: ${util.inspect(val)}`);
+      }
+      continue;
+    }
+
+    flattenObjectWithDottedPaths(obj[key]);
+  }
+};

node_modules/mongoose/lib/helpers/path/parentPaths.js

@@ -0,0 +1,18 @@
+'use strict';
+
+const dotRE = /\./g;
+module.exports = function parentPaths(path) {
+  if (path.indexOf('.') === -1) {
+    return [path];
+  }
+  const pieces = path.split(dotRE);
+  const len = pieces.length;
+  const ret = new Array(len);
+  let cur = '';
+  for (let i = 0; i < len; ++i) {
+    cur += (cur.length !== 0) ? '.' + pieces[i] : pieces[i];
+    ret[i] = cur;
+  }
+
+  return ret;
+};

node_modules/mongoose/lib/helpers/path/setDottedPath.js

@@ -0,0 +1,33 @@
+'use strict';
+
+const specialProperties = require('../specialProperties');
+
+
+module.exports = function setDottedPath(obj, path, val) {
+  if (path.indexOf('.') === -1) {
+    if (specialProperties.has(path)) {
+      return;
+    }
+
+    obj[path] = val;
+    return;
+  }
+  const parts = path.split('.');
+
+  const last = parts.pop();
+  let cur = obj;
+  for (const part of parts) {
+    if (specialProperties.has(part)) {
+      continue;
+    }
+    if (cur[part] == null) {
+      cur[part] = {};
+    }
+
+    cur = cur[part];
+  }
+
+  if (!specialProperties.has(last)) {
+    cur[last] = val;
+  }
+};

node_modules/mongoose/lib/helpers/pluralize.js

@@ -0,0 +1,95 @@
+'use strict';
+
+module.exports = pluralize;
+
+/**
+ * Pluralization rules.
+ */
+
+exports.pluralization = [
+  [/human$/gi, 'humans'],
+  [/(m)an$/gi, '$1en'],
+  [/(pe)rson$/gi, '$1ople'],
+  [/(child)$/gi, '$1ren'],
+  [/^(ox)$/gi, '$1en'],
+  [/(ax|test)is$/gi, '$1es'],
+  [/(octop|vir)us$/gi, '$1i'],
+  [/(alias|status)$/gi, '$1es'],
+  [/(bu)s$/gi, '$1ses'],
+  [/(buffal|tomat|potat)o$/gi, '$1oes'],
+  [/([ti])um$/gi, '$1a'],
+  [/sis$/gi, 'ses'],
+  [/(?:([^f])fe|([lr])f)$/gi, '$1$2ves'],
+  [/(hive)$/gi, '$1s'],
+  [/([^aeiouy]|qu)y$/gi, '$1ies'],
+  [/(x|ch|ss|sh)$/gi, '$1es'],
+  [/(matr|vert|ind)ix|ex$/gi, '$1ices'],
+  [/([m|l])ouse$/gi, '$1ice'],
+  [/(kn|w|l)ife$/gi, '$1ives'],
+  [/(quiz)$/gi, '$1zes'],
+  [/^goose$/i, 'geese'],
+  [/s$/gi, 's'],
+  [/([^a-z])$/, '$1'],
+  [/$/gi, 's']
+];
+const rules = exports.pluralization;
+
+/**
+ * Uncountable words.
+ *
+ * These words are applied while processing the argument to `toCollectionName`.
+ * @api public
+ */
+
+exports.uncountables = [
+  'advice',
+  'energy',
+  'excretion',
+  'digestion',
+  'cooperation',
+  'health',
+  'justice',
+  'labour',
+  'machinery',
+  'equipment',
+  'information',
+  'pollution',
+  'sewage',
+  'paper',
+  'money',
+  'species',
+  'series',
+  'rain',
+  'rice',
+  'fish',
+  'sheep',
+  'moose',
+  'deer',
+  'news',
+  'expertise',
+  'status',
+  'media'
+];
+const uncountables = exports.uncountables;
+
+/**
+ * Pluralize function.
+ *
+ * @author TJ Holowaychuk (extracted from _ext.js_)
+ * @param {String} string to pluralize
+ * @api private
+ */
+
+function pluralize(str) {
+  let found;
+  str = str.toLowerCase();
+  if (!~uncountables.indexOf(str)) {
+    found = rules.filter(function(rule) {
+      return str.match(rule[0]);
+    });
+    if (found[0]) {
+      return str.replace(found[0][0], found[0][1]);
+    }
+  }
+  return str;
+}

node_modules/mongoose/lib/helpers/populate/SkipPopulateValue.js

@@ -0,0 +1,10 @@
+'use strict';
+
+module.exports = function SkipPopulateValue(val) {
+  if (!(this instanceof SkipPopulateValue)) {
+    return new SkipPopulateValue(val);
+  }
+
+  this.val = val;
+  return this;
+};

node_modules/mongoose/lib/helpers/populate/assignRawDocsToIdStructure.js

@@ -0,0 +1,125 @@
+'use strict';
+
+const clone = require('../../helpers/clone');
+const leanPopulateMap = require('./leanPopulateMap');
+const modelSymbol = require('../symbols').modelSymbol;
+const utils = require('../../utils');
+
+module.exports = assignRawDocsToIdStructure;
+
+const kHasArray = Symbol('assignRawDocsToIdStructure.hasArray');
+
+/**
+ * Assign `vals` returned by mongo query to the `rawIds`
+ * structure returned from utils.getVals() honoring
+ * query sort order if specified by user.
+ *
+ * This can be optimized.
+ *
+ * Rules:
+ *
+ *   if the value of the path is not an array, use findOne rules, else find.
+ *   for findOne the results are assigned directly to doc path (including null results).
+ *   for find, if user specified sort order, results are assigned directly
+ *   else documents are put back in original order of array if found in results
+ *
+ * @param {Array} rawIds
+ * @param {Array} resultDocs
+ * @param {Array} resultOrder
+ * @param {Object} options
+ * @param {Boolean} recursed
+ * @api private
+ */
+
+function assignRawDocsToIdStructure(rawIds, resultDocs, resultOrder, options, recursed) {
+  // honor user specified sort order
+  const newOrder = [];
+  const sorting = options.sort && rawIds.length > 1;
+  const nullIfNotFound = options.$nullIfNotFound;
+  let doc;
+  let sid;
+  let id;
+
+  if (utils.isMongooseArray(rawIds)) {
+    rawIds = rawIds.__array;
+  }
+
+  let i = 0;
+  const len = rawIds.length;
+
+  if (sorting && recursed && options[kHasArray] === undefined) {
+    options[kHasArray] = false;
+    for (const key in resultOrder) {
+      if (Array.isArray(resultOrder[key])) {
+        options[kHasArray] = true;
+        break;
+      }
+    }
+  }
+
+  for (i = 0; i < len; ++i) {
+    id = rawIds[i];
+
+    if (Array.isArray(id)) {
+      // handle [ [id0, id2], [id3] ]
+      assignRawDocsToIdStructure(id, resultDocs, resultOrder, options, true);
+      newOrder.push(id);
+      continue;
+    }
+
+    if (id === null && sorting === false) {
+      // keep nulls for findOne unless sorting, which always
+      // removes them (backward compat)
+      newOrder.push(id);
+      continue;
+    }
+
+    sid = String(id);
+    doc = resultDocs[sid];
+    // If user wants separate copies of same doc, use this option
+    if (options.clone && doc != null) {
+      if (options.lean) {
+        const _model = leanPopulateMap.get(doc);
+        doc = clone(doc);
+        leanPopulateMap.set(doc, _model);
+      } else {
+        doc = doc.constructor.hydrate(doc._doc);
+      }
+    }
+
+    if (recursed) {
+      if (doc) {
+        if (sorting) {
+          const _resultOrder = resultOrder[sid];
+          if (options[kHasArray]) {
+            // If result arrays, rely on the MongoDB server response for ordering
+            newOrder.push(doc);
+          } else {
+            newOrder[_resultOrder] = doc;
+          }
+        } else {
+          newOrder.push(doc);
+        }
+      } else if (id != null && id[modelSymbol] != null) {
+        newOrder.push(id);
+      } else {
+        newOrder.push(options.retainNullValues || nullIfNotFound ? null : id);
+      }
+    } else {
+      // apply findOne behavior - if document in results, assign, else assign null
+      newOrder[i] = doc || null;
+    }
+  }
+
+  rawIds.length = 0;
+  if (newOrder.length) {
+    // reassign the documents based on corrected order
+
+    // forEach skips over sparse entries in arrays so we
+    // can safely use this to our advantage dealing with sorted
+    // result sets too.
+    newOrder.forEach(function(doc, i) {
+      rawIds[i] = doc;
+    });
+  }
+}

node_modules/mongoose/lib/helpers/populate/assignVals.js

@@ -0,0 +1,341 @@
+'use strict';
+
+const MongooseMap = require('../../types/map');
+const SkipPopulateValue = require('./SkipPopulateValue');
+const assignRawDocsToIdStructure = require('./assignRawDocsToIdStructure');
+const get = require('../get');
+const getVirtual = require('./getVirtual');
+const leanPopulateMap = require('./leanPopulateMap');
+const lookupLocalFields = require('./lookupLocalFields');
+const markArraySubdocsPopulated = require('./markArraySubdocsPopulated');
+const mpath = require('mpath');
+const sift = require('sift').default;
+const utils = require('../../utils');
+const { populateModelSymbol } = require('../symbols');
+
+module.exports = function assignVals(o) {
+  // Options that aren't explicitly listed in `populateOptions`
+  const userOptions = Object.assign({}, get(o, 'allOptions.options.options'), get(o, 'allOptions.options'));
+  // `o.options` contains options explicitly listed in `populateOptions`, like
+  // `match` and `limit`.
+  const populateOptions = Object.assign({}, o.options, userOptions, {
+    justOne: o.justOne
+  });
+  populateOptions.$nullIfNotFound = o.isVirtual;
+  const populatedModel = o.populatedModel;
+
+  const originalIds = [].concat(o.rawIds);
+
+  // replace the original ids in our intermediate _ids structure
+  // with the documents found by query
+  o.allIds = [].concat(o.allIds);
+  assignRawDocsToIdStructure(o.rawIds, o.rawDocs, o.rawOrder, populateOptions);
+
+  // now update the original documents being populated using the
+  // result structure that contains real documents.
+  const docs = o.docs;
+  const rawIds = o.rawIds;
+  const options = o.options;
+  const count = o.count && o.isVirtual;
+  let i;
+
+  function setValue(val) {
+    if (count) {
+      return val;
+    }
+    if (val instanceof SkipPopulateValue) {
+      return val.val;
+    }
+    if (val === void 0) {
+      return val;
+    }
+
+    const _allIds = o.allIds[i];
+
+    if (o.path.endsWith('.$*')) {
+      // Skip maps re: gh-12494
+      return valueFilter(val, options, populateOptions, _allIds);
+    }
+
+    if (o.justOne === true && Array.isArray(val)) {
+      // Might be an embedded discriminator (re: gh-9244) with multiple models, so make sure to pick the right
+      // model before assigning.
+      const ret = [];
+      for (const doc of val) {
+        const _docPopulatedModel = leanPopulateMap.get(doc);
+        if (_docPopulatedModel == null || _docPopulatedModel === populatedModel) {
+          ret.push(doc);
+        }
+      }
+      // Since we don't want to have to create a new mongoosearray, make sure to
+      // modify the array in place
+      while (val.length > ret.length) {
+        Array.prototype.pop.apply(val, []);
+      }
+      for (let i = 0; i < ret.length; ++i) {
+        val[i] = ret[i];
+      }
+
+      return valueFilter(val[0], options, populateOptions, _allIds);
+    } else if (o.justOne === false && !Array.isArray(val)) {
+      return valueFilter([val], options, populateOptions, _allIds);
+    }
+    return valueFilter(val, options, populateOptions, _allIds);
+  }
+
+  for (i = 0; i < docs.length; ++i) {
+    const _path = o.path.endsWith('.$*') ? o.path.slice(0, -3) : o.path;
+    const existingVal = mpath.get(_path, docs[i], lookupLocalFields);
+    if (existingVal == null && !getVirtual(o.originalModel.schema, _path)) {
+      continue;
+    }
+
+    let valueToSet;
+    if (count) {
+      valueToSet = numDocs(rawIds[i]);
+    } else if (Array.isArray(o.match)) {
+      valueToSet = Array.isArray(rawIds[i]) ?
+        rawIds[i].filter(sift(o.match[i])) :
+        [rawIds[i]].filter(sift(o.match[i]))[0];
+    } else {
+      valueToSet = rawIds[i];
+    }
+
+    // If we're populating a map, the existing value will be an object, so
+    // we need to transform again
+    const originalSchema = o.originalModel.schema;
+    const isDoc = get(docs[i], '$__', null) != null;
+    let isMap = isDoc ?
+      existingVal instanceof Map :
+      utils.isPOJO(existingVal);
+    // If we pass the first check, also make sure the local field's schematype
+    // is map (re: gh-6460)
+    isMap = isMap && get(originalSchema._getSchema(_path), '$isSchemaMap');
+    if (!o.isVirtual && isMap) {
+      const _keys = existingVal instanceof Map ?
+        Array.from(existingVal.keys()) :
+        Object.keys(existingVal);
+      valueToSet = valueToSet.reduce((cur, v, i) => {
+        cur.set(_keys[i], v);
+        return cur;
+      }, new Map());
+    }
+
+    if (isDoc && Array.isArray(valueToSet)) {
+      for (const val of valueToSet) {
+        if (val != null && val.$__ != null) {
+          val.$__.parent = docs[i];
+        }
+      }
+    } else if (isDoc && valueToSet != null && valueToSet.$__ != null) {
+      valueToSet.$__.parent = docs[i];
+    }
+
+    if (o.isVirtual && isDoc) {
+      docs[i].$populated(_path, o.justOne ? originalIds[0] : originalIds, o.allOptions);
+      // If virtual populate and doc is already init-ed, need to walk through
+      // the actual doc to set rather than setting `_doc` directly
+      if (Array.isArray(valueToSet)) {
+        valueToSet = valueToSet.map(v => v == null ? void 0 : v);
+      }
+      mpath.set(_path, valueToSet, docs[i], void 0, setValue, false);
+      continue;
+    }
+
+    const parts = _path.split('.');
+    let cur = docs[i];
+    const curPath = parts[0];
+    for (let j = 0; j < parts.length - 1; ++j) {
+      // If we get to an array with a dotted path, like `arr.foo`, don't set
+      // `foo` on the array.
+      if (Array.isArray(cur) && !utils.isArrayIndex(parts[j])) {
+        break;
+      }
+
+      if (parts[j] === '$*') {
+        break;
+      }
+
+      if (cur[parts[j]] == null) {
+        // If nothing to set, avoid creating an unnecessary array. Otherwise
+        // we'll end up with a single doc in the array with only defaults.
+        // See gh-8342, gh-8455
+        const schematype = originalSchema._getSchema(curPath);
+        if (valueToSet == null && schematype != null && schematype.$isMongooseArray) {
+          break;
+        }
+        cur[parts[j]] = {};
+      }
+      cur = cur[parts[j]];
+      // If the property in MongoDB is a primitive, we won't be able to populate
+      // the nested path, so skip it. See gh-7545
+      if (typeof cur !== 'object') {
+        break;
+      }
+    }
+    if (docs[i].$__) {
+      o.allOptions.options[populateModelSymbol] = o.allOptions.model;
+      docs[i].$populated(_path, o.unpopulatedValues[i], o.allOptions.options);
+
+      if (valueToSet != null && valueToSet.$__ != null) {
+        valueToSet.$__.wasPopulated = { value: o.unpopulatedValues[i] };
+      }
+
+      if (valueToSet instanceof Map && !valueToSet.$isMongooseMap) {
+        valueToSet = new MongooseMap(valueToSet, _path, docs[i], docs[i].schema.path(_path).$__schemaType);
+      }
+    }
+
+    // If lean, need to check that each individual virtual respects
+    // `justOne`, because you may have a populated virtual with `justOne`
+    // underneath an array. See gh-6867
+    mpath.set(_path, valueToSet, docs[i], lookupLocalFields, setValue, false);
+
+    if (docs[i].$__) {
+      markArraySubdocsPopulated(docs[i], [o.allOptions.options]);
+    }
+  }
+};
+
+function numDocs(v) {
+  if (Array.isArray(v)) {
+    // If setting underneath an array of populated subdocs, we may have an
+    // array of arrays. See gh-7573
+    if (v.some(el => Array.isArray(el) || el === null)) {
+      return v.map(el => {
+        if (el == null) {
+          return 0;
+        }
+        if (Array.isArray(el)) {
+          return el.filter(el => el != null).length;
+        }
+        return 1;
+      });
+    }
+    return v.filter(el => el != null).length;
+  }
+  return v == null ? 0 : 1;
+}
+
+/**
+ * 1) Apply backwards compatible find/findOne behavior to sub documents
+ *
+ *    find logic:
+ *      a) filter out non-documents
+ *      b) remove _id from sub docs when user specified
+ *
+ *    findOne
+ *      a) if no doc found, set to null
+ *      b) remove _id from sub docs when user specified
+ *
+ * 2) Remove _ids when specified by users query.
+ *
+ * background:
+ * _ids are left in the query even when user excludes them so
+ * that population mapping can occur.
+ * @param {Any} val
+ * @param {Object} assignmentOpts
+ * @param {Object} populateOptions
+ * @param {Function} [populateOptions.transform]
+ * @param {Boolean} allIds
+ * @api private
+ */
+
+function valueFilter(val, assignmentOpts, populateOptions, allIds) {
+  const userSpecifiedTransform = typeof populateOptions.transform === 'function';
+  const transform = userSpecifiedTransform ? populateOptions.transform : noop;
+  if (Array.isArray(val)) {
+    // find logic
+    const ret = [];
+    const numValues = val.length;
+    for (let i = 0; i < numValues; ++i) {
+      let subdoc = val[i];
+      const _allIds = Array.isArray(allIds) ? allIds[i] : allIds;
+      if (!isPopulatedObject(subdoc) && (!populateOptions.retainNullValues || subdoc != null) && !userSpecifiedTransform) {
+        continue;
+      } else if (!populateOptions.retainNullValues && subdoc == null) {
+        continue;
+      } else if (userSpecifiedTransform) {
+        subdoc = transform(isPopulatedObject(subdoc) ? subdoc : null, _allIds);
+      }
+      maybeRemoveId(subdoc, assignmentOpts);
+      ret.push(subdoc);
+      if (assignmentOpts.originalLimit &&
+          ret.length >= assignmentOpts.originalLimit) {
+        break;
+      }
+    }
+
+    const rLen = ret.length;
+    // Since we don't want to have to create a new mongoosearray, make sure to
+    // modify the array in place
+    while (val.length > rLen) {
+      Array.prototype.pop.apply(val, []);
+    }
+    let i = 0;
+    if (utils.isMongooseArray(val)) {
+      for (i = 0; i < rLen; ++i) {
+        val.set(i, ret[i], true);
+      }
+    } else {
+      for (i = 0; i < rLen; ++i) {
+        val[i] = ret[i];
+      }
+    }
+    return val;
+  }
+
+  // findOne
+  if (isPopulatedObject(val) || utils.isPOJO(val)) {
+    maybeRemoveId(val, assignmentOpts);
+    return transform(val, allIds);
+  }
+  if (val instanceof Map) {
+    return val;
+  }
+
+  if (populateOptions.justOne === false) {
+    return [];
+  }
+
+  return val == null ? transform(val, allIds) : transform(null, allIds);
+}
+
+/**
+ * Remove _id from `subdoc` if user specified "lean" query option
+ * @param {Document} subdoc
+ * @param {Object} assignmentOpts
+ * @api private
+ */
+
+function maybeRemoveId(subdoc, assignmentOpts) {
+  if (subdoc != null && assignmentOpts.excludeId) {
+    if (typeof subdoc.$__setValue === 'function') {
+      delete subdoc._doc._id;
+    } else {
+      delete subdoc._id;
+    }
+  }
+}
+
+/**
+ * Determine if `obj` is something we can set a populated path to. Can be a
+ * document, a lean document, or an array/map that contains docs.
+ * @param {Any} obj
+ * @api private
+ */
+
+function isPopulatedObject(obj) {
+  if (obj == null) {
+    return false;
+  }
+
+  return Array.isArray(obj) ||
+    obj.$isMongooseMap ||
+    obj.$__ != null ||
+    leanPopulateMap.has(obj);
+}
+
+function noop(v) {
+  return v;
+}

node_modules/mongoose/lib/helpers/populate/createPopulateQueryFilter.js

@@ -0,0 +1,97 @@
+'use strict';
+
+const SkipPopulateValue = require('./SkipPopulateValue');
+const parentPaths = require('../path/parentPaths');
+const { trusted } = require('../query/trusted');
+const hasDollarKeys = require('../query/hasDollarKeys');
+
+module.exports = function createPopulateQueryFilter(ids, _match, _foreignField, model, skipInvalidIds) {
+  const match = _formatMatch(_match);
+
+  if (_foreignField.size === 1) {
+    const foreignField = Array.from(_foreignField)[0];
+    const foreignSchemaType = model.schema.path(foreignField);
+    if (foreignField !== '_id' || !match['_id']) {
+      ids = _filterInvalidIds(ids, foreignSchemaType, skipInvalidIds);
+      match[foreignField] = trusted({ $in: ids });
+    } else if (foreignField === '_id' && match['_id']) {
+      const userSpecifiedMatch = hasDollarKeys(match[foreignField]) ?
+        match[foreignField] :
+        { $eq: match[foreignField] };
+      match[foreignField] = { ...trusted({ $in: ids }), ...userSpecifiedMatch };
+    }
+
+    const _parentPaths = parentPaths(foreignField);
+    for (let i = 0; i < _parentPaths.length - 1; ++i) {
+      const cur = _parentPaths[i];
+      if (match[cur] != null && match[cur].$elemMatch != null) {
+        match[cur].$elemMatch[foreignField.slice(cur.length + 1)] = trusted({ $in: ids });
+        delete match[foreignField];
+        break;
+      }
+    }
+  } else {
+    const $or = [];
+    if (Array.isArray(match.$or)) {
+      match.$and = [{ $or: match.$or }, { $or: $or }];
+      delete match.$or;
+    } else {
+      match.$or = $or;
+    }
+    for (const foreignField of _foreignField) {
+      if (foreignField !== '_id' || !match['_id']) {
+        const foreignSchemaType = model.schema.path(foreignField);
+        ids = _filterInvalidIds(ids, foreignSchemaType, skipInvalidIds);
+        $or.push({ [foreignField]: { $in: ids } });
+      } else if (foreignField === '_id' && match['_id']) {
+        const userSpecifiedMatch = hasDollarKeys(match[foreignField]) ?
+          match[foreignField] :
+          { $eq: match[foreignField] };
+        match[foreignField] = { ...trusted({ $in: ids }), ...userSpecifiedMatch };
+      }
+    }
+  }
+
+  return match;
+};
+
+/**
+ * Optionally filter out invalid ids that don't conform to foreign field's schema
+ * to avoid cast errors (gh-7706)
+ * @param {Array} ids
+ * @param {SchemaType} foreignSchemaType
+ * @param {Boolean} [skipInvalidIds]
+ * @api private
+ */
+
+function _filterInvalidIds(ids, foreignSchemaType, skipInvalidIds) {
+  ids = ids.filter(v => !(v instanceof SkipPopulateValue));
+  if (!skipInvalidIds) {
+    return ids;
+  }
+  return ids.filter(id => {
+    try {
+      foreignSchemaType.cast(id);
+      return true;
+    } catch (err) {
+      return false;
+    }
+  });
+}
+
+/**
+ * Format `mod.match` given that it may be an array that we need to $or if
+ * the client has multiple docs with match functions
+ * @param {Array|Any} match
+ * @api private
+ */
+
+function _formatMatch(match) {
+  if (Array.isArray(match)) {
+    if (match.length > 1) {
+      return { $or: [].concat(match.map(m => Object.assign({}, m))) };
+    }
+    return Object.assign({}, match[0]);
+  }
+  return Object.assign({}, match);
+}

node_modules/mongoose/lib/helpers/populate/getModelsMapForPopulate.js

@@ -0,0 +1,733 @@
+'use strict';
+
+const MongooseError = require('../../error/index');
+const SkipPopulateValue = require('./SkipPopulateValue');
+const clone = require('../clone');
+const get = require('../get');
+const getDiscriminatorByValue = require('../discriminator/getDiscriminatorByValue');
+const getConstructorName = require('../getConstructorName');
+const getSchemaTypes = require('./getSchemaTypes');
+const getVirtual = require('./getVirtual');
+const lookupLocalFields = require('./lookupLocalFields');
+const mpath = require('mpath');
+const modelNamesFromRefPath = require('./modelNamesFromRefPath');
+const utils = require('../../utils');
+
+const modelSymbol = require('../symbols').modelSymbol;
+const populateModelSymbol = require('../symbols').populateModelSymbol;
+const schemaMixedSymbol = require('../../schema/symbols').schemaMixedSymbol;
+const StrictPopulate = require('../../error/strictPopulate');
+
+module.exports = function getModelsMapForPopulate(model, docs, options) {
+  let doc;
+  const len = docs.length;
+  const map = [];
+  const modelNameFromQuery = options.model && options.model.modelName || options.model;
+  let schema;
+  let refPath;
+  let modelNames;
+  const available = {};
+
+  const modelSchema = model.schema;
+
+  // Populating a nested path should always be a no-op re: #9073.
+  // People shouldn't do this, but apparently they do.
+  if (options._localModel != null && options._localModel.schema.nested[options.path]) {
+    return [];
+  }
+
+  const _virtualRes = getVirtual(model.schema, options.path);
+  const virtual = _virtualRes == null ? null : _virtualRes.virtual;
+  if (virtual != null) {
+    return _virtualPopulate(model, docs, options, _virtualRes);
+  }
+
+  let allSchemaTypes = getSchemaTypes(model, modelSchema, null, options.path);
+  allSchemaTypes = Array.isArray(allSchemaTypes) ? allSchemaTypes : [allSchemaTypes].filter(v => v != null);
+
+  if (allSchemaTypes.length === 0 && options.strictPopulate !== false && options._localModel != null) {
+    return new StrictPopulate(options._fullPath || options.path);
+  }
+
+  for (let i = 0; i < len; i++) {
+    doc = docs[i];
+    let justOne = null;
+
+    const docSchema = doc != null && doc.$__ != null ? doc.$__schema : modelSchema;
+    schema = getSchemaTypes(model, docSchema, doc, options.path);
+
+    // Special case: populating a path that's a DocumentArray unless
+    // there's an explicit `ref` or `refPath` re: gh-8946
+    if (schema != null &&
+        schema.$isMongooseDocumentArray &&
+        schema.options.ref == null &&
+        schema.options.refPath == null) {
+      continue;
+    }
+    const isUnderneathDocArray = schema && schema.$isUnderneathDocArray;
+    if (isUnderneathDocArray && get(options, 'options.sort') != null) {
+      return new MongooseError('Cannot populate with `sort` on path ' + options.path +
+        ' because it is a subproperty of a document array');
+    }
+
+    modelNames = null;
+    let isRefPath = false;
+    let normalizedRefPath = null;
+    let schemaOptions = null;
+    let modelNamesInOrder = null;
+
+    if (schema != null && schema.instance === 'Embedded') {
+      if (schema.options.ref) {
+        const data = {
+          localField: options.path + '._id',
+          foreignField: '_id',
+          justOne: true
+        };
+        const res = _getModelNames(doc, schema, modelNameFromQuery, model);
+
+        const unpopulatedValue = mpath.get(options.path, doc);
+        const id = mpath.get('_id', unpopulatedValue);
+        addModelNamesToMap(model, map, available, res.modelNames, options, data, id, doc, schemaOptions, unpopulatedValue);
+      }
+      // No-op if no `ref` set. See gh-11538
+      continue;
+    }
+
+    if (Array.isArray(schema)) {
+      const schemasArray = schema;
+      for (const _schema of schemasArray) {
+        let _modelNames;
+        let res;
+        try {
+          res = _getModelNames(doc, _schema, modelNameFromQuery, model);
+          _modelNames = res.modelNames;
+          isRefPath = isRefPath || res.isRefPath;
+          normalizedRefPath = normalizedRefPath || res.refPath;
+          justOne = res.justOne;
+        } catch (error) {
+          return error;
+        }
+
+        if (isRefPath && !res.isRefPath) {
+          continue;
+        }
+        if (!_modelNames) {
+          continue;
+        }
+        modelNames = modelNames || [];
+        for (const modelName of _modelNames) {
+          if (modelNames.indexOf(modelName) === -1) {
+            modelNames.push(modelName);
+          }
+        }
+      }
+    } else {
+      try {
+        const res = _getModelNames(doc, schema, modelNameFromQuery, model);
+        modelNames = res.modelNames;
+        isRefPath = res.isRefPath;
+        normalizedRefPath = normalizedRefPath || res.refPath;
+        justOne = res.justOne;
+        schemaOptions = get(schema, 'options.populate', null);
+        // Dedupe, because `refPath` can return duplicates of the same model name,
+        // and that causes perf issues.
+        if (isRefPath) {
+          modelNamesInOrder = modelNames;
+          modelNames = Array.from(new Set(modelNames));
+        }
+      } catch (error) {
+        return error;
+      }
+
+      if (!modelNames) {
+        continue;
+      }
+    }
+
+    const data = {};
+    const localField = options.path;
+    const foreignField = '_id';
+
+    // `justOne = null` means we don't know from the schema whether the end
+    // result should be an array or a single doc. This can result from
+    // populating a POJO using `Model.populate()`
+    if ('justOne' in options && options.justOne !== void 0) {
+      justOne = options.justOne;
+    } else if (schema && !schema[schemaMixedSymbol]) {
+      // Skip Mixed types because we explicitly don't do casting on those.
+      if (options.path.endsWith('.' + schema.path) || options.path === schema.path) {
+        justOne = Array.isArray(schema) ?
+          schema.every(schema => !schema.$isMongooseArray) :
+          !schema.$isMongooseArray;
+      }
+    }
+
+    if (!modelNames) {
+      continue;
+    }
+
+    data.isVirtual = false;
+    data.justOne = justOne;
+    data.localField = localField;
+    data.foreignField = foreignField;
+
+    // Get local fields
+    const ret = _getLocalFieldValues(doc, localField, model, options, null, schema);
+
+    const id = String(utils.getValue(foreignField, doc));
+    options._docs[id] = Array.isArray(ret) ? ret.slice() : ret;
+
+    let match = get(options, 'match', null);
+
+    const hasMatchFunction = typeof match === 'function';
+    if (hasMatchFunction) {
+      match = match.call(doc, doc);
+    }
+    data.match = match;
+    data.hasMatchFunction = hasMatchFunction;
+    data.isRefPath = isRefPath;
+    data.modelNamesInOrder = modelNamesInOrder;
+
+    if (isRefPath) {
+      const embeddedDiscriminatorModelNames = _findRefPathForDiscriminators(doc,
+        modelSchema, data, options, normalizedRefPath, ret);
+
+      modelNames = embeddedDiscriminatorModelNames || modelNames;
+    }
+
+    try {
+      addModelNamesToMap(model, map, available, modelNames, options, data, ret, doc, schemaOptions);
+    } catch (err) {
+      return err;
+    }
+  }
+  return map;
+
+  function _getModelNames(doc, schema, modelNameFromQuery, model) {
+    let modelNames;
+    let isRefPath = false;
+    let justOne = null;
+
+    const originalSchema = schema;
+    if (schema && schema.instance === 'Array') {
+      schema = schema.caster;
+    }
+    if (schema && schema.$isSchemaMap) {
+      schema = schema.$__schemaType;
+    }
+
+    const ref = schema && schema.options && schema.options.ref;
+    refPath = schema && schema.options && schema.options.refPath;
+    if (schema != null &&
+        schema[schemaMixedSymbol] &&
+        !ref &&
+        !refPath &&
+        !modelNameFromQuery) {
+      return { modelNames: null };
+    }
+
+    if (modelNameFromQuery) {
+      modelNames = [modelNameFromQuery]; // query options
+    } else if (refPath != null) {
+      if (typeof refPath === 'function') {
+        const subdocPath = options.path.slice(0, options.path.length - schema.path.length - 1);
+        const vals = mpath.get(subdocPath, doc, lookupLocalFields);
+        const subdocsBeingPopulated = Array.isArray(vals) ?
+          utils.array.flatten(vals) :
+          (vals ? [vals] : []);
+
+        modelNames = new Set();
+        for (const subdoc of subdocsBeingPopulated) {
+          refPath = refPath.call(subdoc, subdoc, options.path);
+          modelNamesFromRefPath(refPath, doc, options.path, modelSchema, options._queryProjection).
+            forEach(name => modelNames.add(name));
+        }
+        modelNames = Array.from(modelNames);
+      } else {
+        modelNames = modelNamesFromRefPath(refPath, doc, options.path, modelSchema, options._queryProjection);
+      }
+
+      isRefPath = true;
+    } else {
+      let ref;
+      let refPath;
+      let schemaForCurrentDoc;
+      let discriminatorValue;
+      let modelForCurrentDoc = model;
+      const discriminatorKey = model.schema.options.discriminatorKey;
+
+      if (!schema && discriminatorKey && (discriminatorValue = utils.getValue(discriminatorKey, doc))) {
+        // `modelNameForFind` is the discriminator value, so we might need
+        // find the discriminated model name
+        const discriminatorModel = getDiscriminatorByValue(model.discriminators, discriminatorValue) || model;
+        if (discriminatorModel != null) {
+          modelForCurrentDoc = discriminatorModel;
+        } else {
+          try {
+            modelForCurrentDoc = _getModelFromConn(model.db, discriminatorValue);
+          } catch (error) {
+            return error;
+          }
+        }
+
+        schemaForCurrentDoc = modelForCurrentDoc.schema._getSchema(options.path);
+
+        if (schemaForCurrentDoc && schemaForCurrentDoc.caster) {
+          schemaForCurrentDoc = schemaForCurrentDoc.caster;
+        }
+      } else {
+        schemaForCurrentDoc = schema;
+      }
+
+      if (originalSchema && originalSchema.path.endsWith('.$*')) {
+        justOne = !originalSchema.$isMongooseArray && !originalSchema._arrayPath;
+      } else if (schemaForCurrentDoc != null) {
+        justOne = !schemaForCurrentDoc.$isMongooseArray && !schemaForCurrentDoc._arrayPath;
+      }
+
+      if ((ref = get(schemaForCurrentDoc, 'options.ref')) != null) {
+        if (schemaForCurrentDoc != null &&
+            typeof ref === 'function' &&
+            options.path.endsWith('.' + schemaForCurrentDoc.path)) {
+          // Ensure correct context for ref functions: subdoc, not top-level doc. See gh-8469
+          modelNames = new Set();
+
+          const subdocPath = options.path.slice(0, options.path.length - schemaForCurrentDoc.path.length - 1);
+          const vals = mpath.get(subdocPath, doc, lookupLocalFields);
+          const subdocsBeingPopulated = Array.isArray(vals) ?
+            utils.array.flatten(vals) :
+            (vals ? [vals] : []);
+          for (const subdoc of subdocsBeingPopulated) {
+            modelNames.add(handleRefFunction(ref, subdoc));
+          }
+
+          if (subdocsBeingPopulated.length === 0) {
+            modelNames = [handleRefFunction(ref, doc)];
+          } else {
+            modelNames = Array.from(modelNames);
+          }
+        } else {
+          ref = handleRefFunction(ref, doc);
+          modelNames = [ref];
+        }
+      } else if ((schemaForCurrentDoc = get(schema, 'options.refPath')) != null) {
+        isRefPath = true;
+        if (typeof refPath === 'function') {
+          const subdocPath = options.path.slice(0, options.path.length - schemaForCurrentDoc.path.length - 1);
+          const vals = mpath.get(subdocPath, doc, lookupLocalFields);
+          const subdocsBeingPopulated = Array.isArray(vals) ?
+            utils.array.flatten(vals) :
+            (vals ? [vals] : []);
+
+          modelNames = new Set();
+          for (const subdoc of subdocsBeingPopulated) {
+            refPath = refPath.call(subdoc, subdoc, options.path);
+            modelNamesFromRefPath(refPath, doc, options.path, modelSchema, options._queryProjection).
+              forEach(name => modelNames.add(name));
+          }
+          modelNames = Array.from(modelNames);
+        } else {
+          modelNames = modelNamesFromRefPath(refPath, doc, options.path, modelSchema, options._queryProjection);
+        }
+      }
+    }
+
+    if (!modelNames) {
+      // `Model.populate()` on a POJO with no known local model. Default to using the `Model`
+      if (options._localModel == null) {
+        modelNames = [model.modelName];
+      } else {
+        return { modelNames: modelNames, justOne: justOne, isRefPath: isRefPath, refPath: refPath };
+      }
+    }
+
+    if (!Array.isArray(modelNames)) {
+      modelNames = [modelNames];
+    }
+
+    return { modelNames: modelNames, justOne: justOne, isRefPath: isRefPath, refPath: refPath };
+  }
+};
+
+/*!
+ * ignore
+ */
+
+function _virtualPopulate(model, docs, options, _virtualRes) {
+  const map = [];
+  const available = {};
+  const virtual = _virtualRes.virtual;
+
+  for (const doc of docs) {
+    let modelNames = null;
+    const data = {};
+
+    // localField and foreignField
+    let localField;
+    const virtualPrefix = _virtualRes.nestedSchemaPath ?
+      _virtualRes.nestedSchemaPath + '.' : '';
+    if (typeof options.localField === 'string') {
+      localField = options.localField;
+    } else if (typeof virtual.options.localField === 'function') {
+      localField = virtualPrefix + virtual.options.localField.call(doc, doc);
+    } else if (Array.isArray(virtual.options.localField)) {
+      localField = virtual.options.localField.map(field => virtualPrefix + field);
+    } else {
+      localField = virtualPrefix + virtual.options.localField;
+    }
+    data.count = virtual.options.count;
+
+    if (virtual.options.skip != null && !options.hasOwnProperty('skip')) {
+      options.skip = virtual.options.skip;
+    }
+    if (virtual.options.limit != null && !options.hasOwnProperty('limit')) {
+      options.limit = virtual.options.limit;
+    }
+    if (virtual.options.perDocumentLimit != null && !options.hasOwnProperty('perDocumentLimit')) {
+      options.perDocumentLimit = virtual.options.perDocumentLimit;
+    }
+    let foreignField = virtual.options.foreignField;
+
+    if (!localField || !foreignField) {
+      return new MongooseError('If you are populating a virtual, you must set the ' +
+        'localField and foreignField options');
+    }
+
+    if (typeof localField === 'function') {
+      localField = localField.call(doc, doc);
+    }
+    if (typeof foreignField === 'function') {
+      foreignField = foreignField.call(doc, doc);
+    }
+
+    data.isRefPath = false;
+
+    // `justOne = null` means we don't know from the schema whether the end
+    // result should be an array or a single doc. This can result from
+    // populating a POJO using `Model.populate()`
+    let justOne = null;
+    if ('justOne' in options && options.justOne !== void 0) {
+      justOne = options.justOne;
+    }
+
+    if (virtual.options.refPath) {
+      modelNames =
+        modelNamesFromRefPath(virtual.options.refPath, doc, options.path);
+      justOne = !!virtual.options.justOne;
+      data.isRefPath = true;
+    } else if (virtual.options.ref) {
+      let normalizedRef;
+      if (typeof virtual.options.ref === 'function' && !virtual.options.ref[modelSymbol]) {
+        normalizedRef = virtual.options.ref.call(doc, doc);
+      } else {
+        normalizedRef = virtual.options.ref;
+      }
+      justOne = !!virtual.options.justOne;
+      // When referencing nested arrays, the ref should be an Array
+      // of modelNames.
+      if (Array.isArray(normalizedRef)) {
+        modelNames = normalizedRef;
+      } else {
+        modelNames = [normalizedRef];
+      }
+    }
+
+    data.isVirtual = true;
+    data.virtual = virtual;
+    data.justOne = justOne;
+
+    // `match`
+    let match = get(options, 'match', null) ||
+      get(data, 'virtual.options.match', null) ||
+      get(data, 'virtual.options.options.match', null);
+
+    let hasMatchFunction = typeof match === 'function';
+    if (hasMatchFunction) {
+      match = match.call(doc, doc);
+    }
+
+    if (Array.isArray(localField) && Array.isArray(foreignField) && localField.length === foreignField.length) {
+      match = Object.assign({}, match);
+      for (let i = 1; i < localField.length; ++i) {
+        match[foreignField[i]] = convertTo_id(mpath.get(localField[i], doc, lookupLocalFields), model.schema);
+        hasMatchFunction = true;
+      }
+
+      localField = localField[0];
+      foreignField = foreignField[0];
+    }
+    data.localField = localField;
+    data.foreignField = foreignField;
+    data.match = match;
+    data.hasMatchFunction = hasMatchFunction;
+
+    // Get local fields
+    const ret = _getLocalFieldValues(doc, localField, model, options, virtual);
+
+    try {
+      addModelNamesToMap(model, map, available, modelNames, options, data, ret, doc);
+    } catch (err) {
+      return err;
+    }
+  }
+
+  return map;
+}
+
+/*!
+ * ignore
+ */
+
+function addModelNamesToMap(model, map, available, modelNames, options, data, ret, doc, schemaOptions, unpopulatedValue) {
+  // `PopulateOptions#connection`: if the model is passed as a string, the
+  // connection matters because different connections have different models.
+  const connection = options.connection != null ? options.connection : model.db;
+
+  unpopulatedValue = unpopulatedValue === void 0 ? ret : unpopulatedValue;
+  if (Array.isArray(unpopulatedValue)) {
+    unpopulatedValue = utils.cloneArrays(unpopulatedValue);
+  }
+
+  if (modelNames == null) {
+    return;
+  }
+
+  let k = modelNames.length;
+  while (k--) {
+    const modelName = modelNames[k];
+    if (modelName == null) {
+      continue;
+    }
+
+    let Model;
+    if (options.model && options.model[modelSymbol]) {
+      Model = options.model;
+    } else if (modelName[modelSymbol]) {
+      Model = modelName;
+    } else {
+      try {
+        Model = _getModelFromConn(connection, modelName);
+      } catch (err) {
+        if (ret !== void 0) {
+          throw err;
+        }
+        Model = null;
+      }
+    }
+
+    let ids = ret;
+    const flat = Array.isArray(ret) ? utils.array.flatten(ret) : [];
+
+    const modelNamesForRefPath = data.modelNamesInOrder ? data.modelNamesInOrder : modelNames;
+    if (data.isRefPath && Array.isArray(ret) && flat.length === modelNamesForRefPath.length) {
+      ids = flat.filter((val, i) => modelNamesForRefPath[i] === modelName);
+    }
+
+    const perDocumentLimit = options.perDocumentLimit == null ?
+      get(options, 'options.perDocumentLimit', null) :
+      options.perDocumentLimit;
+
+    if (!available[modelName] || perDocumentLimit != null) {
+      const currentOptions = {
+        model: Model
+      };
+      if (data.isVirtual && get(data.virtual, 'options.options')) {
+        currentOptions.options = clone(data.virtual.options.options);
+      } else if (schemaOptions != null) {
+        currentOptions.options = Object.assign({}, schemaOptions);
+      }
+      utils.merge(currentOptions, options);
+
+      // Used internally for checking what model was used to populate this
+      // path.
+      options[populateModelSymbol] = Model;
+      available[modelName] = {
+        model: Model,
+        options: currentOptions,
+        match: data.hasMatchFunction ? [data.match] : data.match,
+        docs: [doc],
+        ids: [ids],
+        allIds: [ret],
+        unpopulatedValues: [unpopulatedValue],
+        localField: new Set([data.localField]),
+        foreignField: new Set([data.foreignField]),
+        justOne: data.justOne,
+        isVirtual: data.isVirtual,
+        virtual: data.virtual,
+        count: data.count,
+        [populateModelSymbol]: Model
+      };
+      map.push(available[modelName]);
+    } else {
+      available[modelName].localField.add(data.localField);
+      available[modelName].foreignField.add(data.foreignField);
+      available[modelName].docs.push(doc);
+      available[modelName].ids.push(ids);
+      available[modelName].allIds.push(ret);
+      available[modelName].unpopulatedValues.push(unpopulatedValue);
+      if (data.hasMatchFunction) {
+        available[modelName].match.push(data.match);
+      }
+    }
+  }
+}
+
+function _getModelFromConn(conn, modelName) {
+  /* If this connection has a parent from `useDb()`, bubble up to parent's models */
+  if (conn.models[modelName] == null && conn._parent != null) {
+    return _getModelFromConn(conn._parent, modelName);
+  }
+
+  return conn.model(modelName);
+}
+
+/*!
+ * ignore
+ */
+
+function handleRefFunction(ref, doc) {
+  if (typeof ref === 'function' && !ref[modelSymbol]) {
+    return ref.call(doc, doc);
+  }
+  return ref;
+}
+
+/*!
+ * ignore
+ */
+
+function _getLocalFieldValues(doc, localField, model, options, virtual, schema) {
+  // Get Local fields
+  const localFieldPathType = model.schema._getPathType(localField);
+  const localFieldPath = localFieldPathType === 'real' ?
+    model.schema.path(localField) :
+    localFieldPathType.schema;
+  const localFieldGetters = localFieldPath && localFieldPath.getters ?
+    localFieldPath.getters : [];
+
+  localField = localFieldPath != null && localFieldPath.instance === 'Embedded' ? localField + '._id' : localField;
+
+  const _populateOptions = get(options, 'options', {});
+
+  const getters = 'getters' in _populateOptions ?
+    _populateOptions.getters :
+    get(virtual, 'options.getters', false);
+  if (localFieldGetters.length !== 0 && getters) {
+    const hydratedDoc = (doc.$__ != null) ? doc : model.hydrate(doc);
+    const localFieldValue = utils.getValue(localField, doc);
+    if (Array.isArray(localFieldValue)) {
+      const localFieldHydratedValue = utils.getValue(localField.split('.').slice(0, -1), hydratedDoc);
+      return localFieldValue.map((localFieldArrVal, localFieldArrIndex) =>
+        localFieldPath.applyGetters(localFieldArrVal, localFieldHydratedValue[localFieldArrIndex]));
+    } else {
+      return localFieldPath.applyGetters(localFieldValue, hydratedDoc);
+    }
+  } else {
+    return convertTo_id(mpath.get(localField, doc, lookupLocalFields), schema);
+  }
+}
+
+/**
+ * Retrieve the _id of `val` if a Document or Array of Documents.
+ *
+ * @param {Array|Document|Any} val
+ * @param {Schema} schema
+ * @return {Array|Document|Any}
+ * @api private
+ */
+
+function convertTo_id(val, schema) {
+  if (val != null && val.$__ != null) {
+    return val._id;
+  }
+  if (val != null && val._id != null && (schema == null || !schema.$isSchemaMap)) {
+    return val._id;
+  }
+
+  if (Array.isArray(val)) {
+    const rawVal = val.__array != null ? val.__array : val;
+    for (let i = 0; i < rawVal.length; ++i) {
+      if (rawVal[i] != null && rawVal[i].$__ != null) {
+        rawVal[i] = rawVal[i]._id;
+      }
+    }
+    if (utils.isMongooseArray(val) && val.$schema()) {
+      return val.$schema()._castForPopulate(val, val.$parent());
+    }
+
+    return [].concat(val);
+  }
+
+  // `populate('map')` may be an object if populating on a doc that hasn't
+  // been hydrated yet
+  if (getConstructorName(val) === 'Object' &&
+      // The intent here is we should only flatten the object if we expect
+      // to get a Map in the end. Avoid doing this for mixed types.
+      (schema == null || schema[schemaMixedSymbol] == null)) {
+    const ret = [];
+    for (const key of Object.keys(val)) {
+      ret.push(val[key]);
+    }
+    return ret;
+  }
+  // If doc has already been hydrated, e.g. `doc.populate('map')`
+  // then `val` will already be a map
+  if (val instanceof Map) {
+    return Array.from(val.values());
+  }
+
+  return val;
+}
+
+/*!
+ * ignore
+ */
+
+function _findRefPathForDiscriminators(doc, modelSchema, data, options, normalizedRefPath, ret) {
+  // Re: gh-8452. Embedded discriminators may not have `refPath`, so clear
+  // out embedded discriminator docs that don't have a `refPath` on the
+  // populated path.
+  if (!data.isRefPath || normalizedRefPath == null) {
+    return;
+  }
+
+  const pieces = normalizedRefPath.split('.');
+  let cur = '';
+  let modelNames = void 0;
+  for (let i = 0; i < pieces.length; ++i) {
+    const piece = pieces[i];
+    cur = cur + (cur.length === 0 ? '' : '.') + piece;
+    const schematype = modelSchema.path(cur);
+    if (schematype != null &&
+        schematype.$isMongooseArray &&
+        schematype.caster.discriminators != null &&
+        Object.keys(schematype.caster.discriminators).length !== 0) {
+      const subdocs = utils.getValue(cur, doc);
+      const remnant = options.path.substring(cur.length + 1);
+      const discriminatorKey = schematype.caster.schema.options.discriminatorKey;
+      modelNames = [];
+      for (const subdoc of subdocs) {
+        const discriminatorName = utils.getValue(discriminatorKey, subdoc);
+        const discriminator = schematype.caster.discriminators[discriminatorName];
+        const discriminatorSchema = discriminator && discriminator.schema;
+        if (discriminatorSchema == null) {
+          continue;
+        }
+        const _path = discriminatorSchema.path(remnant);
+        if (_path == null || _path.options.refPath == null) {
+          const docValue = utils.getValue(data.localField.substring(cur.length + 1), subdoc);
+          ret.forEach((v, i) => {
+            if (v === docValue) {
+              ret[i] = SkipPopulateValue(v);
+            }
+          });
+          continue;
+        }
+        const modelName = utils.getValue(pieces.slice(i + 1).join('.'), subdoc);
+        modelNames.push(modelName);
+      }
+    }
+  }
+
+  return modelNames;
+}

node_modules/mongoose/lib/helpers/populate/getSchemaTypes.js

@@ -0,0 +1,233 @@
+'use strict';
+
+/*!
+ * ignore
+ */
+
+const Mixed = require('../../schema/mixed');
+const get = require('../get');
+const getDiscriminatorByValue = require('../discriminator/getDiscriminatorByValue');
+const leanPopulateMap = require('./leanPopulateMap');
+const mpath = require('mpath');
+
+const populateModelSymbol = require('../symbols').populateModelSymbol;
+
+/**
+ * Given a model and its schema, find all possible schema types for `path`,
+ * including searching through discriminators. If `doc` is specified, will
+ * use the doc's values for discriminator keys when searching, otherwise
+ * will search all discriminators.
+ *
+ * @param {Model} model
+ * @param {Schema} schema
+ * @param {Object} doc POJO
+ * @param {string} path
+ * @api private
+ */
+
+module.exports = function getSchemaTypes(model, schema, doc, path) {
+  const pathschema = schema.path(path);
+  const topLevelDoc = doc;
+  if (pathschema) {
+    return pathschema;
+  }
+
+  const discriminatorKey = schema.discriminatorMapping &&
+    schema.discriminatorMapping.key;
+  if (discriminatorKey && model != null) {
+    if (doc != null && doc[discriminatorKey] != null) {
+      const discriminator = getDiscriminatorByValue(model.discriminators, doc[discriminatorKey]);
+      schema = discriminator ? discriminator.schema : schema;
+    } else if (model.discriminators != null) {
+      return Object.keys(model.discriminators).reduce((arr, name) => {
+        const disc = model.discriminators[name];
+        return arr.concat(getSchemaTypes(disc, disc.schema, null, path));
+      }, []);
+    }
+  }
+
+  function search(parts, schema, subdoc, nestedPath) {
+    let p = parts.length + 1;
+    let foundschema;
+    let trypath;
+
+    while (p--) {
+      trypath = parts.slice(0, p).join('.');
+      foundschema = schema.path(trypath);
+      if (foundschema == null) {
+        continue;
+      }
+
+      if (foundschema.caster) {
+        // array of Mixed?
+        if (foundschema.caster instanceof Mixed) {
+          return foundschema.caster;
+        }
+
+        let schemas = null;
+        if (foundschema.schema != null && foundschema.schema.discriminators != null) {
+          const discriminators = foundschema.schema.discriminators;
+          const discriminatorKeyPath = trypath + '.' +
+            foundschema.schema.options.discriminatorKey;
+          const keys = subdoc ? mpath.get(discriminatorKeyPath, subdoc) || [] : [];
+          schemas = Object.keys(discriminators).
+            reduce(function(cur, discriminator) {
+              const tiedValue = discriminators[discriminator].discriminatorMapping.value;
+              if (doc == null || keys.indexOf(discriminator) !== -1 || keys.indexOf(tiedValue) !== -1) {
+                cur.push(discriminators[discriminator]);
+              }
+              return cur;
+            }, []);
+        }
+
+        // Now that we found the array, we need to check if there
+        // are remaining document paths to look up for casting.
+        // Also we need to handle array.$.path since schema.path
+        // doesn't work for that.
+        // If there is no foundschema.schema we are dealing with
+        // a path like array.$
+        if (p !== parts.length && foundschema.schema) {
+          let ret;
+          if (parts[p] === '$') {
+            if (p + 1 === parts.length) {
+              // comments.$
+              return foundschema;
+            }
+            // comments.$.comments.$.title
+            ret = search(
+              parts.slice(p + 1),
+              schema,
+              subdoc ? mpath.get(trypath, subdoc) : null,
+              nestedPath.concat(parts.slice(0, p))
+            );
+            if (ret) {
+              ret.$isUnderneathDocArray = ret.$isUnderneathDocArray ||
+                !foundschema.schema.$isSingleNested;
+            }
+            return ret;
+          }
+
+          if (schemas != null && schemas.length > 0) {
+            ret = [];
+            for (const schema of schemas) {
+              const _ret = search(
+                parts.slice(p),
+                schema,
+                subdoc ? mpath.get(trypath, subdoc) : null,
+                nestedPath.concat(parts.slice(0, p))
+              );
+              if (_ret != null) {
+                _ret.$isUnderneathDocArray = _ret.$isUnderneathDocArray ||
+                  !foundschema.schema.$isSingleNested;
+                if (_ret.$isUnderneathDocArray) {
+                  ret.$isUnderneathDocArray = true;
+                }
+                ret.push(_ret);
+              }
+            }
+            return ret;
+          } else {
+            ret = search(
+              parts.slice(p),
+              foundschema.schema,
+              subdoc ? mpath.get(trypath, subdoc) : null,
+              nestedPath.concat(parts.slice(0, p))
+            );
+
+            if (ret) {
+              ret.$isUnderneathDocArray = ret.$isUnderneathDocArray ||
+                !foundschema.schema.$isSingleNested;
+            }
+            return ret;
+          }
+        } else if (p !== parts.length &&
+            foundschema.$isMongooseArray &&
+            foundschema.casterConstructor.$isMongooseArray) {
+          // Nested arrays. Drill down to the bottom of the nested array.
+          let type = foundschema;
+          while (type.$isMongooseArray && !type.$isMongooseDocumentArray) {
+            type = type.casterConstructor;
+          }
+
+          const ret = search(
+            parts.slice(p),
+            type.schema,
+            null,
+            nestedPath.concat(parts.slice(0, p))
+          );
+          if (ret != null) {
+            return ret;
+          }
+
+          if (type.schema.discriminators) {
+            const discriminatorPaths = [];
+            for (const discriminatorName of Object.keys(type.schema.discriminators)) {
+              const _schema = type.schema.discriminators[discriminatorName] || type.schema;
+              const ret = search(parts.slice(p), _schema, null, nestedPath.concat(parts.slice(0, p)));
+              if (ret != null) {
+                discriminatorPaths.push(ret);
+              }
+            }
+            if (discriminatorPaths.length > 0) {
+              return discriminatorPaths;
+            }
+          }
+        }
+      } else if (foundschema.$isSchemaMap && foundschema.$__schemaType instanceof Mixed) {
+        return foundschema.$__schemaType;
+      }
+
+      const fullPath = nestedPath.concat([trypath]).join('.');
+      if (topLevelDoc != null && topLevelDoc.$__ && topLevelDoc.$populated(fullPath) && p < parts.length) {
+        const model = doc.$__.populated[fullPath].options[populateModelSymbol];
+        if (model != null) {
+          const ret = search(
+            parts.slice(p),
+            model.schema,
+            subdoc ? mpath.get(trypath, subdoc) : null,
+            nestedPath.concat(parts.slice(0, p))
+          );
+
+          if (ret) {
+            ret.$isUnderneathDocArray = ret.$isUnderneathDocArray ||
+              !model.schema.$isSingleNested;
+          }
+          return ret;
+        }
+      }
+
+      const _val = get(topLevelDoc, trypath);
+      if (_val != null) {
+        const model = Array.isArray(_val) && _val.length > 0 ?
+          leanPopulateMap.get(_val[0]) :
+          leanPopulateMap.get(_val);
+        // Populated using lean, `leanPopulateMap` value is the foreign model
+        const schema = model != null ? model.schema : null;
+        if (schema != null) {
+          const ret = search(
+            parts.slice(p),
+            schema,
+            subdoc ? mpath.get(trypath, subdoc) : null,
+            nestedPath.concat(parts.slice(0, p))
+          );
+
+          if (ret != null) {
+            ret.$isUnderneathDocArray = ret.$isUnderneathDocArray ||
+              !schema.$isSingleNested;
+            return ret;
+          }
+        }
+      }
+      return foundschema;
+    }
+  }
+  // look for arrays
+  const parts = path.split('.');
+  for (let i = 0; i < parts.length; ++i) {
+    if (parts[i] === '$') {
+      // Re: gh-5628, because `schema.path()` doesn't take $ into account.
+      parts[i] = '0';
+    }
+  }
+  return search(parts, schema, doc, []);
+};

node_modules/mongoose/lib/helpers/populate/getVirtual.js

@@ -0,0 +1,72 @@
+'use strict';
+
+module.exports = getVirtual;
+
+/*!
+ * ignore
+ */
+
+function getVirtual(schema, name) {
+  if (schema.virtuals[name]) {
+    return { virtual: schema.virtuals[name], path: void 0 };
+  }
+
+  const parts = name.split('.');
+  let cur = '';
+  let nestedSchemaPath = '';
+  for (let i = 0; i < parts.length; ++i) {
+    cur += (cur.length > 0 ? '.' : '') + parts[i];
+    if (schema.virtuals[cur]) {
+      if (i === parts.length - 1) {
+        return { virtual: schema.virtuals[cur], path: nestedSchemaPath };
+      }
+      continue;
+    }
+
+    if (schema.nested[cur]) {
+      continue;
+    }
+
+    if (schema.paths[cur] && schema.paths[cur].schema) {
+      schema = schema.paths[cur].schema;
+      const rest = parts.slice(i + 1).join('.');
+
+      if (schema.virtuals[rest]) {
+        if (i === parts.length - 2) {
+          return {
+            virtual: schema.virtuals[rest],
+            nestedSchemaPath: [nestedSchemaPath, cur].filter(v => !!v).join('.')
+          };
+        }
+        continue;
+      }
+
+      if (i + 1 < parts.length && schema.discriminators) {
+        for (const key of Object.keys(schema.discriminators)) {
+          const res = getVirtual(schema.discriminators[key], rest);
+          if (res != null) {
+            const _path = [nestedSchemaPath, cur, res.nestedSchemaPath].
+              filter(v => !!v).join('.');
+            return {
+              virtual: res.virtual,
+              nestedSchemaPath: _path
+            };
+          }
+        }
+      }
+
+      nestedSchemaPath += (nestedSchemaPath.length > 0 ? '.' : '') + cur;
+      cur = '';
+      continue;
+    }
+
+    if (schema.discriminators) {
+      for (const discriminatorKey of Object.keys(schema.discriminators)) {
+        const virtualFromDiscriminator = getVirtual(schema.discriminators[discriminatorKey], name);
+        if (virtualFromDiscriminator) return virtualFromDiscriminator;
+      }
+    }
+
+    return null;
+  }
+}

node_modules/mongoose/lib/helpers/populate/leanPopulateMap.js

@@ -0,0 +1,7 @@
+'use strict';
+
+/*!
+ * ignore
+ */
+
+module.exports = new WeakMap();

node_modules/mongoose/lib/helpers/populate/lookupLocalFields.js

@@ -0,0 +1,40 @@
+'use strict';
+
+module.exports = function lookupLocalFields(cur, path, val) {
+  if (cur == null) {
+    return cur;
+  }
+
+  if (cur._doc != null) {
+    cur = cur._doc;
+  }
+
+  if (arguments.length >= 3) {
+    if (typeof cur !== 'object') {
+      return void 0;
+    }
+    if (val === void 0) {
+      return void 0;
+    }
+    if (cur instanceof Map) {
+      cur.set(path, val);
+    } else {
+      cur[path] = val;
+    }
+    return val;
+  }
+
+
+  // Support populating paths under maps using `map.$*.subpath`
+  if (path === '$*') {
+    return cur instanceof Map ?
+      Array.from(cur.values()) :
+      Object.keys(cur).map(key => cur[key]);
+  }
+
+  if (cur instanceof Map) {
+    return cur.get(path);
+  }
+
+  return cur[path];
+};

node_modules/mongoose/lib/helpers/populate/markArraySubdocsPopulated.js

@@ -0,0 +1,47 @@
+'use strict';
+
+const utils = require('../../utils');
+
+/**
+ * If populating a path within a document array, make sure each
+ * subdoc within the array knows its subpaths are populated.
+ *
+ * #### Example:
+ *
+ *     const doc = await Article.findOne().populate('comments.author');
+ *     doc.comments[0].populated('author'); // Should be set
+ *
+ * @param {Document} doc
+ * @param {Object} [populated]
+ * @api private
+ */
+
+module.exports = function markArraySubdocsPopulated(doc, populated) {
+  if (doc._id == null || populated == null || populated.length === 0) {
+    return;
+  }
+
+  const id = String(doc._id);
+  for (const item of populated) {
+    if (item.isVirtual) {
+      continue;
+    }
+    const path = item.path;
+    const pieces = path.split('.');
+    for (let i = 0; i < pieces.length - 1; ++i) {
+      const subpath = pieces.slice(0, i + 1).join('.');
+      const rest = pieces.slice(i + 1).join('.');
+      const val = doc.get(subpath);
+      if (val == null) {
+        continue;
+      }
+
+      if (utils.isMongooseDocumentArray(val)) {
+        for (let j = 0; j < val.length; ++j) {
+          val[j].populated(rest, item._docs[id] == null ? void 0 : item._docs[id][j], item);
+        }
+        break;
+      }
+    }
+  }
+};

node_modules/mongoose/lib/helpers/populate/modelNamesFromRefPath.js

@@ -0,0 +1,68 @@
+'use strict';
+
+const MongooseError = require('../../error/mongooseError');
+const isPathExcluded = require('../projection/isPathExcluded');
+const lookupLocalFields = require('./lookupLocalFields');
+const mpath = require('mpath');
+const util = require('util');
+const utils = require('../../utils');
+
+const hasNumericPropRE = /(\.\d+$|\.\d+\.)/g;
+
+module.exports = function modelNamesFromRefPath(refPath, doc, populatedPath, modelSchema, queryProjection) {
+  if (refPath == null) {
+    return [];
+  }
+
+  if (typeof refPath === 'string' && queryProjection != null && isPathExcluded(queryProjection, refPath)) {
+    throw new MongooseError('refPath `' + refPath + '` must not be excluded in projection, got ' +
+      util.inspect(queryProjection));
+  }
+
+  // If populated path has numerics, the end `refPath` should too. For example,
+  // if populating `a.0.b` instead of `a.b` and `b` has `refPath = a.c`, we
+  // should return `a.0.c` for the refPath.
+
+  if (hasNumericPropRE.test(populatedPath)) {
+    const chunks = populatedPath.split(hasNumericPropRE);
+
+    if (chunks[chunks.length - 1] === '') {
+      throw new Error('Can\'t populate individual element in an array');
+    }
+
+    let _refPath = '';
+    let _remaining = refPath;
+    // 2nd, 4th, etc. will be numeric props. For example: `[ 'a', '.0.', 'b' ]`
+    for (let i = 0; i < chunks.length; i += 2) {
+      const chunk = chunks[i];
+      if (_remaining.startsWith(chunk + '.')) {
+        _refPath += _remaining.substring(0, chunk.length) + chunks[i + 1];
+        _remaining = _remaining.substring(chunk.length + 1);
+      } else if (i === chunks.length - 1) {
+        _refPath += _remaining;
+        _remaining = '';
+        break;
+      } else {
+        throw new Error('Could not normalize ref path, chunk ' + chunk + ' not in populated path');
+      }
+    }
+
+    const refValue = mpath.get(_refPath, doc, lookupLocalFields);
+    let modelNames = Array.isArray(refValue) ? refValue : [refValue];
+    modelNames = utils.array.flatten(modelNames);
+    return modelNames;
+  }
+
+  const refValue = mpath.get(refPath, doc, lookupLocalFields);
+
+  let modelNames;
+  if (modelSchema != null && modelSchema.virtuals.hasOwnProperty(refPath)) {
+    modelNames = [modelSchema.virtuals[refPath].applyGetters(void 0, doc)];
+  } else {
+    modelNames = Array.isArray(refValue) ? refValue : [refValue];
+  }
+
+  modelNames = utils.array.flatten(modelNames);
+
+  return modelNames;
+};

node_modules/mongoose/lib/helpers/populate/removeDeselectedForeignField.js

@@ -0,0 +1,31 @@
+'use strict';
+
+const get = require('../get');
+const mpath = require('mpath');
+const parseProjection = require('../projection/parseProjection');
+
+/*!
+ * ignore
+ */
+
+module.exports = function removeDeselectedForeignField(foreignFields, options, docs) {
+  const projection = parseProjection(get(options, 'select', null), true) ||
+    parseProjection(get(options, 'options.select', null), true);
+
+  if (projection == null) {
+    return;
+  }
+  for (const foreignField of foreignFields) {
+    if (!projection.hasOwnProperty('-' + foreignField)) {
+      continue;
+    }
+
+    for (const val of docs) {
+      if (val.$__ != null) {
+        mpath.unset(foreignField, val._doc);
+      } else {
+        mpath.unset(foreignField, val);
+      }
+    }
+  }
+};

node_modules/mongoose/lib/helpers/populate/validateRef.js

@@ -0,0 +1,19 @@
+'use strict';
+
+const MongooseError = require('../../error/mongooseError');
+const util = require('util');
+
+module.exports = validateRef;
+
+function validateRef(ref, path) {
+  if (typeof ref === 'string') {
+    return;
+  }
+
+  if (typeof ref === 'function') {
+    return;
+  }
+
+  throw new MongooseError('Invalid ref at path "' + path + '". Got ' +
+    util.inspect(ref, { depth: 0 }));
+}

node_modules/mongoose/lib/helpers/printJestWarning.js

@@ -0,0 +1,17 @@
+'use strict';
+
+const utils = require('../utils');
+
+if (typeof jest !== 'undefined' && typeof window !== 'undefined') {
+  utils.warn('Mongoose: looks like you\'re trying to test a Mongoose app ' +
+    'with Jest\'s default jsdom test environment. Please make sure you read ' +
+    'Mongoose\'s docs on configuring Jest to test Node.js apps: ' +
+    'https://mongoosejs.com/docs/jest.html');
+}
+
+if (typeof jest !== 'undefined' && setTimeout.clock != null && typeof setTimeout.clock.Date === 'function') {
+  utils.warn('Mongoose: looks like you\'re trying to test a Mongoose app ' +
+    'with Jest\'s mock timers enabled. Please make sure you read ' +
+    'Mongoose\'s docs on configuring Jest to test Node.js apps: ' +
+    'https://mongoosejs.com/docs/jest.html');
+}

node_modules/mongoose/lib/helpers/processConnectionOptions.js

@@ -0,0 +1,64 @@
+'use strict';
+
+const clone = require('./clone');
+const MongooseError = require('../error/index');
+
+function processConnectionOptions(uri, options) {
+  const opts = options ? options : {};
+  const readPreference = opts.readPreference
+    ? opts.readPreference
+    : getUriReadPreference(uri);
+
+  const resolvedOpts = (readPreference && readPreference !== 'primary' && readPreference !== 'primaryPreferred')
+    ? resolveOptsConflicts(readPreference, opts)
+    : opts;
+
+  return clone(resolvedOpts);
+}
+
+function resolveOptsConflicts(pref, opts) {
+  // don't silently override user-provided indexing options
+  if (setsIndexOptions(opts) && setsSecondaryRead(pref)) {
+    throwReadPreferenceError();
+  }
+
+  // if user has not explicitly set any auto-indexing options,
+  // we can silently default them all to false
+  else {
+    return defaultIndexOptsToFalse(opts);
+  }
+}
+
+function setsIndexOptions(opts) {
+  const configIdx = opts.config && opts.config.autoIndex;
+  const { autoCreate, autoIndex } = opts;
+  return !!(configIdx || autoCreate || autoIndex);
+}
+
+function setsSecondaryRead(prefString) {
+  return !!(prefString === 'secondary' || prefString === 'secondaryPreferred');
+}
+
+function getUriReadPreference(connectionString) {
+  const exp = /(?:&|\?)readPreference=(\w+)(?:&|$)/;
+  const match = exp.exec(connectionString);
+  return match ? match[1] : null;
+}
+
+function defaultIndexOptsToFalse(opts) {
+  opts.config = { autoIndex: false };
+  opts.autoCreate = false;
+  opts.autoIndex = false;
+  return opts;
+}
+
+function throwReadPreferenceError() {
+  throw new MongooseError(
+    'MongoDB prohibits index creation on connections that read from ' +
+            'non-primary replicas.  Connections that set "readPreference" to "secondary" or ' +
+            '"secondaryPreferred" may not opt-in to the following connection options: ' +
+            'autoCreate, autoIndex'
+  );
+}
+
+module.exports = processConnectionOptions;

node_modules/mongoose/lib/helpers/projection/applyProjection.js

@@ -0,0 +1,77 @@
+'use strict';
+
+const hasIncludedChildren = require('./hasIncludedChildren');
+const isExclusive = require('./isExclusive');
+const isInclusive = require('./isInclusive');
+const isPOJO = require('../../utils').isPOJO;
+
+module.exports = function applyProjection(doc, projection, _hasIncludedChildren) {
+  if (projection == null) {
+    return doc;
+  }
+  if (doc == null) {
+    return doc;
+  }
+
+  let exclude = null;
+  if (isInclusive(projection)) {
+    exclude = false;
+  } else if (isExclusive(projection)) {
+    exclude = true;
+  }
+
+  if (exclude == null) {
+    return doc;
+  } else if (exclude) {
+    _hasIncludedChildren = _hasIncludedChildren || hasIncludedChildren(projection);
+    return applyExclusiveProjection(doc, projection, _hasIncludedChildren);
+  } else {
+    _hasIncludedChildren = _hasIncludedChildren || hasIncludedChildren(projection);
+    return applyInclusiveProjection(doc, projection, _hasIncludedChildren);
+  }
+};
+
+function applyExclusiveProjection(doc, projection, hasIncludedChildren, projectionLimb, prefix) {
+  if (doc == null || typeof doc !== 'object') {
+    return doc;
+  }
+  const ret = { ...doc };
+  projectionLimb = prefix ? (projectionLimb || {}) : projection;
+
+  for (const key of Object.keys(ret)) {
+    const fullPath = prefix ? prefix + '.' + key : key;
+    if (projection.hasOwnProperty(fullPath) || projectionLimb.hasOwnProperty(key)) {
+      if (isPOJO(projection[fullPath]) || isPOJO(projectionLimb[key])) {
+        ret[key] = applyExclusiveProjection(ret[key], projection, hasIncludedChildren, projectionLimb[key], fullPath);
+      } else {
+        delete ret[key];
+      }
+    } else if (hasIncludedChildren[fullPath]) {
+      ret[key] = applyExclusiveProjection(ret[key], projection, hasIncludedChildren, projectionLimb[key], fullPath);
+    }
+  }
+  return ret;
+}
+
+function applyInclusiveProjection(doc, projection, hasIncludedChildren, projectionLimb, prefix) {
+  if (doc == null || typeof doc !== 'object') {
+    return doc;
+  }
+  const ret = { ...doc };
+  projectionLimb = prefix ? (projectionLimb || {}) : projection;
+
+  for (const key of Object.keys(ret)) {
+    const fullPath = prefix ? prefix + '.' + key : key;
+    if (projection.hasOwnProperty(fullPath) || projectionLimb.hasOwnProperty(key)) {
+      if (isPOJO(projection[fullPath]) || isPOJO(projectionLimb[key])) {
+        ret[key] = applyInclusiveProjection(ret[key], projection, hasIncludedChildren, projectionLimb[key], fullPath);
+      }
+      continue;
+    } else if (hasIncludedChildren[fullPath]) {
+      ret[key] = applyInclusiveProjection(ret[key], projection, hasIncludedChildren, projectionLimb[key], fullPath);
+    } else {
+      delete ret[key];
+    }
+  }
+  return ret;
+}

node_modules/mongoose/lib/helpers/projection/hasIncludedChildren.js

@@ -0,0 +1,40 @@
+'use strict';
+
+/**
+ * Creates an object that precomputes whether a given path has child fields in
+ * the projection.
+ *
+ * #### Example:
+ *
+ *     const res = hasIncludedChildren({ 'a.b.c': 0 });
+ *     res.a; // 1
+ *     res['a.b']; // 1
+ *     res['a.b.c']; // 1
+ *     res['a.c']; // undefined
+ *
+ * @param {Object} fields
+ * @api private
+ */
+
+module.exports = function hasIncludedChildren(fields) {
+  const hasIncludedChildren = {};
+  const keys = Object.keys(fields);
+
+  for (const key of keys) {
+    if (key.indexOf('.') === -1) {
+      hasIncludedChildren[key] = 1;
+      continue;
+    }
+    const parts = key.split('.');
+    let c = parts[0];
+
+    for (let i = 0; i < parts.length; ++i) {
+      hasIncludedChildren[c] = 1;
+      if (i + 1 < parts.length) {
+        c = c + '.' + parts[i + 1];
+      }
+    }
+  }
+
+  return hasIncludedChildren;
+};

node_modules/mongoose/lib/helpers/projection/isDefiningProjection.js

@@ -0,0 +1,18 @@
+'use strict';
+
+/*!
+ * ignore
+ */
+
+module.exports = function isDefiningProjection(val) {
+  if (val == null) {
+    // `undefined` or `null` become exclusive projections
+    return true;
+  }
+  if (typeof val === 'object') {
+    // Only cases where a value does **not** define whether the whole projection
+    // is inclusive or exclusive are `$meta` and `$slice`.
+    return !('$meta' in val) && !('$slice' in val);
+  }
+  return true;
+};

node_modules/mongoose/lib/helpers/projection/isExclusive.js

@@ -0,0 +1,35 @@
+'use strict';
+
+const isDefiningProjection = require('./isDefiningProjection');
+
+/*!
+ * ignore
+ */
+
+module.exports = function isExclusive(projection) {
+  if (projection == null) {
+    return null;
+  }
+
+  const keys = Object.keys(projection);
+  let ki = keys.length;
+  let exclude = null;
+
+  if (ki === 1 && keys[0] === '_id') {
+    exclude = !projection._id;
+  } else {
+    while (ki--) {
+      // Does this projection explicitly define inclusion/exclusion?
+      // Explicitly avoid `$meta` and `$slice`
+      const key = keys[ki];
+      if (key !== '_id' && isDefiningProjection(projection[key])) {
+        exclude = (projection[key] != null && typeof projection[key] === 'object') ?
+          isExclusive(projection[key]) :
+          !projection[key];
+        break;
+      }
+    }
+  }
+
+  return exclude;
+};

node_modules/mongoose/lib/helpers/projection/isInclusive.js

@@ -0,0 +1,38 @@
+'use strict';
+
+const isDefiningProjection = require('./isDefiningProjection');
+
+/*!
+ * ignore
+ */
+
+module.exports = function isInclusive(projection) {
+  if (projection == null) {
+    return false;
+  }
+
+  const props = Object.keys(projection);
+  const numProps = props.length;
+  if (numProps === 0) {
+    return false;
+  }
+
+  for (let i = 0; i < numProps; ++i) {
+    const prop = props[i];
+    // Plus paths can't define the projection (see gh-7050)
+    if (prop.startsWith('+')) {
+      continue;
+    }
+    // If field is truthy (1, true, etc.) and not an object, then this
+    // projection must be inclusive. If object, assume its $meta, $slice, etc.
+    if (isDefiningProjection(projection[prop]) && !!projection[prop]) {
+      if (projection[prop] != null && typeof projection[prop] === 'object') {
+        return isInclusive(projection[prop]);
+      } else {
+        return !!projection[prop];
+      }
+    }
+  }
+
+  return false;
+};

node_modules/mongoose/lib/helpers/projection/isPathExcluded.js

@@ -0,0 +1,40 @@
+'use strict';
+
+const isDefiningProjection = require('./isDefiningProjection');
+
+/**
+ * Determines if `path` is excluded by `projection`
+ *
+ * @param {Object} projection
+ * @param {String} path
+ * @return {Boolean}
+ * @api private
+ */
+
+module.exports = function isPathExcluded(projection, path) {
+  if (projection == null) {
+    return false;
+  }
+
+  if (path === '_id') {
+    return projection._id === 0;
+  }
+
+  const paths = Object.keys(projection);
+  let type = null;
+
+  for (const _path of paths) {
+    if (isDefiningProjection(projection[_path])) {
+      type = projection[path] === 1 ? 'inclusive' : 'exclusive';
+      break;
+    }
+  }
+
+  if (type === 'inclusive') {
+    return projection[path] !== 1;
+  }
+  if (type === 'exclusive') {
+    return projection[path] === 0;
+  }
+  return false;
+};

node_modules/mongoose/lib/helpers/projection/isPathSelectedInclusive.js

@@ -0,0 +1,28 @@
+'use strict';
+
+/*!
+ * ignore
+ */
+
+module.exports = function isPathSelectedInclusive(fields, path) {
+  const chunks = path.split('.');
+  let cur = '';
+  let j;
+  let keys;
+  let numKeys;
+  for (let i = 0; i < chunks.length; ++i) {
+    cur += cur.length ? '.' : '' + chunks[i];
+    if (fields[cur]) {
+      keys = Object.keys(fields);
+      numKeys = keys.length;
+      for (j = 0; j < numKeys; ++j) {
+        if (keys[i].indexOf(cur + '.') === 0 && keys[i].indexOf(path) !== 0) {
+          continue;
+        }
+      }
+      return true;
+    }
+  }
+
+  return false;
+};

node_modules/mongoose/lib/helpers/projection/isSubpath.js

@@ -0,0 +1,14 @@
+'use strict';
+
+/**
+ * Determines if `path2` is a subpath of or equal to `path1`
+ *
+ * @param {string} path1
+ * @param {string} path2
+ * @return {Boolean}
+ * @api private
+ */
+
+module.exports = function isSubpath(path1, path2) {
+  return path1 === path2 || path2.startsWith(path1 + '.');
+};

node_modules/mongoose/lib/helpers/projection/parseProjection.js

@@ -0,0 +1,33 @@
+'use strict';
+
+/**
+ * Convert a string or array into a projection object, retaining all
+ * `-` and `+` paths.
+ */
+
+module.exports = function parseProjection(v, retainMinusPaths) {
+  const type = typeof v;
+
+  if (type === 'string') {
+    v = v.split(/\s+/);
+  }
+  if (!Array.isArray(v) && Object.prototype.toString.call(v) !== '[object Arguments]') {
+    return v;
+  }
+
+  const len = v.length;
+  const ret = {};
+  for (let i = 0; i < len; ++i) {
+    let field = v[i];
+    if (!field) {
+      continue;
+    }
+    const include = '-' == field[0] ? 0 : 1;
+    if (!retainMinusPaths && include === 0) {
+      field = field.substring(1);
+    }
+    ret[field] = include;
+  }
+
+  return ret;
+};

node_modules/mongoose/lib/helpers/promiseOrCallback.js

@@ -0,0 +1,54 @@
+'use strict';
+
+const immediate = require('./immediate');
+
+const emittedSymbol = Symbol('mongoose:emitted');
+
+module.exports = function promiseOrCallback(callback, fn, ee, Promise) {
+  if (typeof callback === 'function') {
+    try {
+      return fn(function(error) {
+        if (error != null) {
+          if (ee != null && ee.listeners != null && ee.listeners('error').length > 0 && !error[emittedSymbol]) {
+            error[emittedSymbol] = true;
+            ee.emit('error', error);
+          }
+          try {
+            callback(error);
+          } catch (error) {
+            return immediate(() => {
+              throw error;
+            });
+          }
+          return;
+        }
+        callback.apply(this, arguments);
+      });
+    } catch (error) {
+      if (ee != null && ee.listeners != null && ee.listeners('error').length > 0 && !error[emittedSymbol]) {
+        error[emittedSymbol] = true;
+        ee.emit('error', error);
+      }
+
+      return callback(error);
+    }
+  }
+
+  Promise = Promise || global.Promise;
+
+  return new Promise((resolve, reject) => {
+    fn(function(error, res) {
+      if (error != null) {
+        if (ee != null && ee.listeners != null && ee.listeners('error').length > 0 && !error[emittedSymbol]) {
+          error[emittedSymbol] = true;
+          ee.emit('error', error);
+        }
+        return reject(error);
+      }
+      if (arguments.length > 2) {
+        return resolve(Array.prototype.slice.call(arguments, 1));
+      }
+      resolve(res);
+    });
+  });
+};

node_modules/mongoose/lib/helpers/query/applyGlobalOption.js

@@ -0,0 +1,29 @@
+'use strict';
+
+const utils = require('../../utils');
+
+function applyGlobalMaxTimeMS(options, model) {
+  applyGlobalOption(options, model, 'maxTimeMS');
+}
+
+function applyGlobalDiskUse(options, model) {
+  applyGlobalOption(options, model, 'allowDiskUse');
+}
+
+module.exports = {
+  applyGlobalMaxTimeMS,
+  applyGlobalDiskUse
+};
+
+
+function applyGlobalOption(options, model, optionName) {
+  if (utils.hasUserDefinedProperty(options, optionName)) {
+    return;
+  }
+
+  if (utils.hasUserDefinedProperty(model.db.options, optionName)) {
+    options[optionName] = model.db.options[optionName];
+  } else if (utils.hasUserDefinedProperty(model.base.options, optionName)) {
+    options[optionName] = model.base.options[optionName];
+  }
+}

node_modules/mongoose/lib/helpers/query/applyQueryMiddleware.js

@@ -0,0 +1,54 @@
+'use strict';
+
+/*!
+ * ignore
+ */
+
+module.exports = applyQueryMiddleware;
+
+const validOps = require('./validOps');
+
+/*!
+ * ignore
+ */
+
+applyQueryMiddleware.middlewareFunctions = validOps.concat([
+  'validate'
+]);
+
+/**
+ * Apply query middleware
+ *
+ * @param {Query} Query constructor
+ * @param {Model} model
+ * @api private
+ */
+
+function applyQueryMiddleware(Query, model) {
+  const queryMiddleware = model.schema.s.hooks.filter(hook => {
+    const contexts = _getContexts(hook);
+    if (hook.name === 'validate') {
+      return !!contexts.query;
+    }
+    if (hook.name === 'deleteOne' || hook.name === 'updateOne') {
+      return !!contexts.query || Object.keys(contexts).length === 0;
+    }
+    if (hook.query != null || hook.document != null) {
+      return !!hook.query;
+    }
+    return true;
+  });
+
+  Query.prototype._queryMiddleware = queryMiddleware;
+}
+
+function _getContexts(hook) {
+  const ret = {};
+  if (hook.hasOwnProperty('query')) {
+    ret.query = hook.query;
+  }
+  if (hook.hasOwnProperty('document')) {
+    ret.document = hook.document;
+  }
+  return ret;
+}

node_modules/mongoose/lib/helpers/query/cast$expr.js

@@ -0,0 +1,282 @@
+'use strict';
+
+const CastError = require('../../error/cast');
+const StrictModeError = require('../../error/strict');
+const castNumber = require('../../cast/number');
+
+const booleanComparison = new Set(['$and', '$or']);
+const comparisonOperator = new Set(['$cmp', '$eq', '$lt', '$lte', '$gt', '$gte']);
+const arithmeticOperatorArray = new Set([
+  // avoid casting '$add' or '$subtract', because expressions can be either number or date,
+  // and we don't have a good way of inferring which arguments should be numbers and which should
+  // be dates.
+  '$multiply',
+  '$divide',
+  '$log',
+  '$mod',
+  '$trunc',
+  '$avg',
+  '$max',
+  '$min',
+  '$stdDevPop',
+  '$stdDevSamp',
+  '$sum'
+]);
+const arithmeticOperatorNumber = new Set([
+  '$abs',
+  '$exp',
+  '$ceil',
+  '$floor',
+  '$ln',
+  '$log10',
+  '$round',
+  '$sqrt',
+  '$sin',
+  '$cos',
+  '$tan',
+  '$asin',
+  '$acos',
+  '$atan',
+  '$atan2',
+  '$asinh',
+  '$acosh',
+  '$atanh',
+  '$sinh',
+  '$cosh',
+  '$tanh',
+  '$degreesToRadians',
+  '$radiansToDegrees'
+]);
+const arrayElementOperators = new Set([
+  '$arrayElemAt',
+  '$first',
+  '$last'
+]);
+const dateOperators = new Set([
+  '$year',
+  '$month',
+  '$week',
+  '$dayOfMonth',
+  '$dayOfYear',
+  '$hour',
+  '$minute',
+  '$second',
+  '$isoDayOfWeek',
+  '$isoWeekYear',
+  '$isoWeek',
+  '$millisecond'
+]);
+const expressionOperator = new Set(['$not']);
+
+module.exports = function cast$expr(val, schema, strictQuery) {
+  if (typeof val !== 'object' || val === null) {
+    throw new Error('`$expr` must be an object');
+  }
+
+  return _castExpression(val, schema, strictQuery);
+};
+
+function _castExpression(val, schema, strictQuery) {
+  // Preserve the value if it represents a path or if it's null
+  if (isPath(val) || val === null) {
+    return val;
+  }
+
+  if (val.$cond != null) {
+    if (Array.isArray(val.$cond)) {
+      val.$cond = val.$cond.map(expr => _castExpression(expr, schema, strictQuery));
+    } else {
+      val.$cond.if = _castExpression(val.$cond.if, schema, strictQuery);
+      val.$cond.then = _castExpression(val.$cond.then, schema, strictQuery);
+      val.$cond.else = _castExpression(val.$cond.else, schema, strictQuery);
+    }
+  } else if (val.$ifNull != null) {
+    val.$ifNull.map(v => _castExpression(v, schema, strictQuery));
+  } else if (val.$switch != null) {
+    val.branches.map(v => _castExpression(v, schema, strictQuery));
+    val.default = _castExpression(val.default, schema, strictQuery);
+  }
+
+  const keys = Object.keys(val);
+  for (const key of keys) {
+    if (booleanComparison.has(key)) {
+      val[key] = val[key].map(v => _castExpression(v, schema, strictQuery));
+    } else if (comparisonOperator.has(key)) {
+      val[key] = castComparison(val[key], schema, strictQuery);
+    } else if (arithmeticOperatorArray.has(key)) {
+      val[key] = castArithmetic(val[key], schema, strictQuery);
+    } else if (arithmeticOperatorNumber.has(key)) {
+      val[key] = castNumberOperator(val[key], schema, strictQuery);
+    } else if (expressionOperator.has(key)) {
+      val[key] = _castExpression(val[key], schema, strictQuery);
+    }
+  }
+
+  if (val.$in) {
+    val.$in = castIn(val.$in, schema, strictQuery);
+  }
+  if (val.$size) {
+    val.$size = castNumberOperator(val.$size, schema, strictQuery);
+  }
+
+  _omitUndefined(val);
+
+  return val;
+}
+
+function _omitUndefined(val) {
+  const keys = Object.keys(val);
+  for (let i = 0, len = keys.length; i < len; ++i) {
+    (val[keys[i]] === void 0) && delete val[keys[i]];
+  }
+}
+
+// { $op: <number> }
+function castNumberOperator(val) {
+  if (!isLiteral(val)) {
+    return val;
+  }
+
+  try {
+    return castNumber(val);
+  } catch (err) {
+    throw new CastError('Number', val);
+  }
+}
+
+function castIn(val, schema, strictQuery) {
+  const path = val[1];
+  if (!isPath(path)) {
+    return val;
+  }
+  const search = val[0];
+
+  const schematype = schema.path(path.slice(1));
+  if (schematype === null) {
+    if (strictQuery === false) {
+      return val;
+    } else if (strictQuery === 'throw') {
+      throw new StrictModeError('$in');
+    }
+
+    return void 0;
+  }
+
+  if (!schematype.$isMongooseArray) {
+    throw new Error('Path must be an array for $in');
+  }
+
+  return [
+    schematype.$isMongooseDocumentArray ? schematype.$embeddedSchemaType.cast(search) : schematype.caster.cast(search),
+    path
+  ];
+}
+
+// { $op: [<number>, <number>] }
+function castArithmetic(val) {
+  if (!Array.isArray(val)) {
+    if (!isLiteral(val)) {
+      return val;
+    }
+    try {
+      return castNumber(val);
+    } catch (err) {
+      throw new CastError('Number', val);
+    }
+  }
+
+  return val.map(v => {
+    if (!isLiteral(v)) {
+      return v;
+    }
+    try {
+      return castNumber(v);
+    } catch (err) {
+      throw new CastError('Number', v);
+    }
+  });
+}
+
+// { $op: [expression, expression] }
+function castComparison(val, schema, strictQuery) {
+  if (!Array.isArray(val) || val.length !== 2) {
+    throw new Error('Comparison operator must be an array of length 2');
+  }
+
+  val[0] = _castExpression(val[0], schema, strictQuery);
+  const lhs = val[0];
+
+  if (isLiteral(val[1])) {
+    let path = null;
+    let schematype = null;
+    let caster = null;
+    if (isPath(lhs)) {
+      path = lhs.slice(1);
+      schematype = schema.path(path);
+    } else if (typeof lhs === 'object' && lhs != null) {
+      for (const key of Object.keys(lhs)) {
+        if (dateOperators.has(key) && isPath(lhs[key])) {
+          path = lhs[key].slice(1) + '.' + key;
+          caster = castNumber;
+        } else if (arrayElementOperators.has(key) && isPath(lhs[key])) {
+          path = lhs[key].slice(1) + '.' + key;
+          schematype = schema.path(lhs[key].slice(1));
+          if (schematype != null) {
+            if (schematype.$isMongooseDocumentArray) {
+              schematype = schematype.$embeddedSchemaType;
+            } else if (schematype.$isMongooseArray) {
+              schematype = schematype.caster;
+            }
+          }
+        }
+      }
+    }
+
+    const is$literal = typeof val[1] === 'object' && val[1] != null && val[1].$literal != null;
+    if (schematype != null) {
+      if (is$literal) {
+        val[1] = { $literal: schematype.cast(val[1].$literal) };
+      } else {
+        val[1] = schematype.cast(val[1]);
+      }
+    } else if (caster != null) {
+      if (is$literal) {
+        try {
+          val[1] = { $literal: caster(val[1].$literal) };
+        } catch (err) {
+          throw new CastError(caster.name.replace(/^cast/, ''), val[1], path + '.$literal');
+        }
+      } else {
+        try {
+          val[1] = caster(val[1]);
+        } catch (err) {
+          throw new CastError(caster.name.replace(/^cast/, ''), val[1], path);
+        }
+      }
+    } else if (path != null && strictQuery === true) {
+      return void 0;
+    } else if (path != null && strictQuery === 'throw') {
+      throw new StrictModeError(path);
+    }
+  } else {
+    val[1] = _castExpression(val[1]);
+  }
+
+  return val;
+}
+
+function isPath(val) {
+  return typeof val === 'string' && val[0] === '$';
+}
+
+function isLiteral(val) {
+  if (typeof val === 'string' && val[0] === '$') {
+    return false;
+  }
+  if (typeof val === 'object' && val !== null && Object.keys(val).find(key => key[0] === '$')) {
+    // The `$literal` expression can make an object a literal
+    // https://www.mongodb.com/docs/manual/reference/operator/aggregation/literal/#mongodb-expression-exp.-literal
+    return val.$literal != null;
+  }
+  return true;
+}

node_modules/mongoose/lib/helpers/query/castFilterPath.js

@@ -0,0 +1,55 @@
+'use strict';
+
+const isOperator = require('./isOperator');
+
+module.exports = function castFilterPath(query, schematype, val) {
+  const ctx = query;
+  const any$conditionals = Object.keys(val).some(isOperator);
+
+  if (!any$conditionals) {
+    return schematype.castForQuery(
+      null,
+      val,
+      ctx
+    );
+  }
+
+  const ks = Object.keys(val);
+
+  let k = ks.length;
+
+  while (k--) {
+    const $cond = ks[k];
+    const nested = val[$cond];
+
+    if ($cond === '$not') {
+      if (nested && schematype && !schematype.caster) {
+        const _keys = Object.keys(nested);
+        if (_keys.length && isOperator(_keys[0])) {
+          for (const key of Object.keys(nested)) {
+            nested[key] = schematype.castForQuery(
+              key,
+              nested[key],
+              ctx
+            );
+          }
+        } else {
+          val[$cond] = schematype.castForQuery(
+            $cond,
+            nested,
+            ctx
+          );
+        }
+        continue;
+      }
+    } else {
+      val[$cond] = schematype.castForQuery(
+        $cond,
+        nested,
+        ctx
+      );
+    }
+  }
+
+  return val;
+};

node_modules/mongoose/lib/helpers/query/castUpdate.js

@@ -0,0 +1,565 @@
+'use strict';
+
+const CastError = require('../../error/cast');
+const MongooseError = require('../../error/mongooseError');
+const StrictModeError = require('../../error/strict');
+const ValidationError = require('../../error/validation');
+const castNumber = require('../../cast/number');
+const cast = require('../../cast');
+const getConstructorName = require('../getConstructorName');
+const getEmbeddedDiscriminatorPath = require('./getEmbeddedDiscriminatorPath');
+const handleImmutable = require('./handleImmutable');
+const moveImmutableProperties = require('../update/moveImmutableProperties');
+const schemaMixedSymbol = require('../../schema/symbols').schemaMixedSymbol;
+const setDottedPath = require('../path/setDottedPath');
+const utils = require('../../utils');
+
+/**
+ * Casts an update op based on the given schema
+ *
+ * @param {Schema} schema
+ * @param {Object} obj
+ * @param {Object} [options]
+ * @param {Boolean} [options.overwrite] defaults to false
+ * @param {Boolean|String} [options.strict] defaults to true
+ * @param {Query} context passed to setters
+ * @return {Boolean} true iff the update is non-empty
+ * @api private
+ */
+module.exports = function castUpdate(schema, obj, options, context, filter) {
+  if (obj == null) {
+    return undefined;
+  }
+  options = options || {};
+  // Update pipeline
+  if (Array.isArray(obj)) {
+    const len = obj.length;
+    for (let i = 0; i < len; ++i) {
+      const ops = Object.keys(obj[i]);
+      for (const op of ops) {
+        obj[i][op] = castPipelineOperator(op, obj[i][op]);
+      }
+    }
+    return obj;
+  }
+
+  if (options.upsert && !options.overwrite) {
+    moveImmutableProperties(schema, obj, context);
+  }
+
+  const ops = Object.keys(obj);
+  let i = ops.length;
+  const ret = {};
+  let val;
+  let hasDollarKey = false;
+  const overwrite = options.overwrite;
+
+  filter = filter || {};
+  while (i--) {
+    const op = ops[i];
+    // if overwrite is set, don't do any of the special $set stuff
+    if (op[0] !== '$' && !overwrite) {
+      // fix up $set sugar
+      if (!ret.$set) {
+        if (obj.$set) {
+          ret.$set = obj.$set;
+        } else {
+          ret.$set = {};
+        }
+      }
+      ret.$set[op] = obj[op];
+      ops.splice(i, 1);
+      if (!~ops.indexOf('$set')) ops.push('$set');
+    } else if (op === '$set') {
+      if (!ret.$set) {
+        ret[op] = obj[op];
+      }
+    } else {
+      ret[op] = obj[op];
+    }
+  }
+  // cast each value
+  i = ops.length;
+  while (i--) {
+    const op = ops[i];
+    val = ret[op];
+    hasDollarKey = hasDollarKey || op.startsWith('$');
+
+    if (val &&
+        typeof val === 'object' &&
+        !Buffer.isBuffer(val) &&
+        (!overwrite || hasDollarKey)) {
+      walkUpdatePath(schema, val, op, options, context, filter);
+    } else if (overwrite && ret && typeof ret === 'object') {
+      walkUpdatePath(schema, ret, '$set', options, context, filter);
+    } else {
+      const msg = 'Invalid atomic update value for ' + op + '. '
+          + 'Expected an object, received ' + typeof val;
+      throw new Error(msg);
+    }
+
+    if (op.startsWith('$') && utils.isEmptyObject(val)) {
+      delete ret[op];
+    }
+  }
+
+  if (Object.keys(ret).length === 0 &&
+      options.upsert &&
+      Object.keys(filter).length > 0) {
+    // Trick the driver into allowing empty upserts to work around
+    // https://github.com/mongodb/node-mongodb-native/pull/2490
+    return { $setOnInsert: filter };
+  }
+  return ret;
+};
+
+/*!
+ * ignore
+ */
+
+function castPipelineOperator(op, val) {
+  if (op === '$unset') {
+    if (typeof val !== 'string' && (!Array.isArray(val) || val.find(v => typeof v !== 'string'))) {
+      throw new MongooseError('Invalid $unset in pipeline, must be ' +
+        ' a string or an array of strings');
+    }
+    return val;
+  }
+  if (op === '$project') {
+    if (val == null || typeof val !== 'object') {
+      throw new MongooseError('Invalid $project in pipeline, must be an object');
+    }
+    return val;
+  }
+  if (op === '$addFields' || op === '$set') {
+    if (val == null || typeof val !== 'object') {
+      throw new MongooseError('Invalid ' + op + ' in pipeline, must be an object');
+    }
+    return val;
+  } else if (op === '$replaceRoot' || op === '$replaceWith') {
+    if (val == null || typeof val !== 'object') {
+      throw new MongooseError('Invalid ' + op + ' in pipeline, must be an object');
+    }
+    return val;
+  }
+
+  throw new MongooseError('Invalid update pipeline operator: "' + op + '"');
+}
+
+/**
+ * Walk each path of obj and cast its values
+ * according to its schema.
+ *
+ * @param {Schema} schema
+ * @param {Object} obj part of a query
+ * @param {String} op the atomic operator ($pull, $set, etc)
+ * @param {Object} [options]
+ * @param {Boolean|String} [options.strict]
+ * @param {Query} context
+ * @param {Object} filter
+ * @param {String} pref path prefix (internal only)
+ * @return {Bool} true if this path has keys to update
+ * @api private
+ */
+
+function walkUpdatePath(schema, obj, op, options, context, filter, pref) {
+  const strict = options.strict;
+  const prefix = pref ? pref + '.' : '';
+  const keys = Object.keys(obj);
+  let i = keys.length;
+  let hasKeys = false;
+  let schematype;
+  let key;
+  let val;
+
+  let aggregatedError = null;
+
+  const strictMode = strict != null ? strict : schema.options.strict;
+
+  while (i--) {
+    key = keys[i];
+    val = obj[key];
+
+    // `$pull` is special because we need to cast the RHS as a query, not as
+    // an update.
+    if (op === '$pull') {
+      schematype = schema._getSchema(prefix + key);
+      if (schematype != null && schematype.schema != null) {
+        obj[key] = cast(schematype.schema, obj[key], options, context);
+        hasKeys = true;
+        continue;
+      }
+    }
+
+    const discriminatorKey = (prefix ? prefix + key : key);
+    if (
+      schema.discriminatorMapping != null &&
+      discriminatorKey === schema.options.discriminatorKey &&
+      schema.discriminatorMapping.value !== obj[key] &&
+      !options.overwriteDiscriminatorKey
+    ) {
+      if (strictMode === 'throw') {
+        const err = new Error('Can\'t modify discriminator key "' + discriminatorKey + '" on discriminator model');
+        aggregatedError = _appendError(err, context, discriminatorKey, aggregatedError);
+        continue;
+      } else if (strictMode) {
+        delete obj[key];
+        continue;
+      }
+    }
+
+    if (getConstructorName(val) === 'Object') {
+      // watch for embedded doc schemas
+      schematype = schema._getSchema(prefix + key);
+
+      if (schematype == null) {
+        const _res = getEmbeddedDiscriminatorPath(schema, obj, filter, prefix + key, options);
+        if (_res.schematype != null) {
+          schematype = _res.schematype;
+        }
+      }
+
+      if (op !== '$setOnInsert' &&
+          !options.overwrite &&
+          handleImmutable(schematype, strict, obj, key, prefix + key, context)) {
+        continue;
+      }
+
+      if (schematype && schematype.caster && op in castOps) {
+        // embedded doc schema
+        if ('$each' in val) {
+          hasKeys = true;
+          try {
+            obj[key] = {
+              $each: castUpdateVal(schematype, val.$each, op, key, context, prefix + key)
+            };
+          } catch (error) {
+            aggregatedError = _appendError(error, context, key, aggregatedError);
+          }
+
+          if (val.$slice != null) {
+            obj[key].$slice = val.$slice | 0;
+          }
+
+          if (val.$sort) {
+            obj[key].$sort = val.$sort;
+          }
+
+          if (val.$position != null) {
+            obj[key].$position = castNumber(val.$position);
+          }
+        } else {
+          if (schematype != null && schematype.$isSingleNested) {
+            const _strict = strict == null ? schematype.schema.options.strict : strict;
+            try {
+              obj[key] = schematype.castForQuery(null, val, context, { strict: _strict });
+            } catch (error) {
+              aggregatedError = _appendError(error, context, key, aggregatedError);
+            }
+          } else {
+            try {
+              obj[key] = castUpdateVal(schematype, val, op, key, context, prefix + key);
+            } catch (error) {
+              aggregatedError = _appendError(error, context, key, aggregatedError);
+            }
+          }
+
+          if (obj[key] === void 0) {
+            delete obj[key];
+            continue;
+          }
+
+          hasKeys = true;
+        }
+      } else if ((op === '$currentDate') || (op in castOps && schematype)) {
+        // $currentDate can take an object
+        try {
+          obj[key] = castUpdateVal(schematype, val, op, key, context, prefix + key);
+        } catch (error) {
+          aggregatedError = _appendError(error, context, key, aggregatedError);
+        }
+
+        if (obj[key] === void 0) {
+          delete obj[key];
+          continue;
+        }
+
+        hasKeys = true;
+      } else {
+        const pathToCheck = (prefix + key);
+        const v = schema._getPathType(pathToCheck);
+        let _strict = strict;
+        if (v && v.schema && _strict == null) {
+          _strict = v.schema.options.strict;
+        }
+
+        if (v.pathType === 'undefined') {
+          if (_strict === 'throw') {
+            throw new StrictModeError(pathToCheck);
+          } else if (_strict) {
+            delete obj[key];
+            continue;
+          }
+        }
+
+        // gh-2314
+        // we should be able to set a schema-less field
+        // to an empty object literal
+        hasKeys |= walkUpdatePath(schema, val, op, options, context, filter, prefix + key) ||
+          (utils.isObject(val) && Object.keys(val).length === 0);
+      }
+    } else {
+      const checkPath = (key === '$each' || key === '$or' || key === '$and' || key === '$in') ?
+        pref : prefix + key;
+      schematype = schema._getSchema(checkPath);
+
+      // You can use `$setOnInsert` with immutable keys
+      if (op !== '$setOnInsert' &&
+          !options.overwrite &&
+          handleImmutable(schematype, strict, obj, key, prefix + key, context)) {
+        continue;
+      }
+
+      let pathDetails = schema._getPathType(checkPath);
+
+      // If no schema type, check for embedded discriminators because the
+      // filter or update may imply an embedded discriminator type. See #8378
+      if (schematype == null) {
+        const _res = getEmbeddedDiscriminatorPath(schema, obj, filter, checkPath, options);
+        if (_res.schematype != null) {
+          schematype = _res.schematype;
+          pathDetails = _res.type;
+        }
+      }
+
+      let isStrict = strict;
+      if (pathDetails && pathDetails.schema && strict == null) {
+        isStrict = pathDetails.schema.options.strict;
+      }
+
+      const skip = isStrict &&
+        !schematype &&
+        !/real|nested/.test(pathDetails.pathType);
+
+      if (skip) {
+        // Even if strict is `throw`, avoid throwing an error because of
+        // virtuals because of #6731
+        if (isStrict === 'throw' && schema.virtuals[checkPath] == null) {
+          throw new StrictModeError(prefix + key);
+        } else {
+          delete obj[key];
+        }
+      } else {
+        // gh-1845 temporary fix: ignore $rename. See gh-3027 for tracking
+        // improving this.
+        if (op === '$rename') {
+          hasKeys = true;
+          continue;
+        }
+
+        try {
+          if (prefix.length === 0 || key.indexOf('.') === -1) {
+            obj[key] = castUpdateVal(schematype, val, op, key, context, prefix + key);
+          } else {
+            // Setting a nested dotted path that's in the schema. We don't allow paths with '.' in
+            // a schema, so replace the dotted path with a nested object to avoid ending up with
+            // dotted properties in the updated object. See (gh-10200)
+            setDottedPath(obj, key, castUpdateVal(schematype, val, op, key, context, prefix + key));
+            delete obj[key];
+          }
+        } catch (error) {
+          aggregatedError = _appendError(error, context, key, aggregatedError);
+        }
+
+        if (Array.isArray(obj[key]) && (op === '$addToSet' || op === '$push') && key !== '$each') {
+          if (schematype &&
+              schematype.caster &&
+              !schematype.caster.$isMongooseArray &&
+              !schematype.caster[schemaMixedSymbol]) {
+            obj[key] = { $each: obj[key] };
+          }
+        }
+
+        if (obj[key] === void 0) {
+          delete obj[key];
+          continue;
+        }
+
+        hasKeys = true;
+      }
+    }
+  }
+
+  if (aggregatedError != null) {
+    throw aggregatedError;
+  }
+
+  return hasKeys;
+}
+
+/*!
+ * ignore
+ */
+
+function _appendError(error, query, key, aggregatedError) {
+  if (typeof query !== 'object' || !query.options.multipleCastError) {
+    throw error;
+  }
+  aggregatedError = aggregatedError || new ValidationError();
+  aggregatedError.addError(key, error);
+  return aggregatedError;
+}
+
+/**
+ * These operators should be cast to numbers instead
+ * of their path schema type.
+ * @api private
+ */
+
+const numberOps = {
+  $pop: 1,
+  $inc: 1
+};
+
+/**
+ * These ops require no casting because the RHS doesn't do anything.
+ * @api private
+ */
+
+const noCastOps = {
+  $unset: 1
+};
+
+/**
+ * These operators require casting docs
+ * to real Documents for Update operations.
+ * @api private
+ */
+
+const castOps = {
+  $push: 1,
+  $addToSet: 1,
+  $set: 1,
+  $setOnInsert: 1
+};
+
+/*!
+ * ignore
+ */
+
+const overwriteOps = {
+  $set: 1,
+  $setOnInsert: 1
+};
+
+/**
+ * Casts `val` according to `schema` and atomic `op`.
+ *
+ * @param {SchemaType} schema
+ * @param {Object} val
+ * @param {String} op the atomic operator ($pull, $set, etc)
+ * @param {String} $conditional
+ * @param {Query} context
+ * @param {String} path
+ * @api private
+ */
+
+function castUpdateVal(schema, val, op, $conditional, context, path) {
+  if (!schema) {
+    // non-existing schema path
+    if (op in numberOps) {
+      try {
+        return castNumber(val);
+      } catch (err) {
+        throw new CastError('number', val, path);
+      }
+    }
+    return val;
+  }
+
+  // console.log('CastUpdateVal', path, op, val, schema);
+
+  const cond = schema.caster && op in castOps &&
+      (utils.isObject(val) || Array.isArray(val));
+  if (cond && !overwriteOps[op]) {
+    // Cast values for ops that add data to MongoDB.
+    // Ensures embedded documents get ObjectIds etc.
+    let schemaArrayDepth = 0;
+    let cur = schema;
+    while (cur.$isMongooseArray) {
+      ++schemaArrayDepth;
+      cur = cur.caster;
+    }
+    let arrayDepth = 0;
+    let _val = val;
+    while (Array.isArray(_val)) {
+      ++arrayDepth;
+      _val = _val[0];
+    }
+
+    const additionalNesting = schemaArrayDepth - arrayDepth;
+    while (arrayDepth < schemaArrayDepth) {
+      val = [val];
+      ++arrayDepth;
+    }
+
+    let tmp = schema.applySetters(Array.isArray(val) ? val : [val], context);
+
+    for (let i = 0; i < additionalNesting; ++i) {
+      tmp = tmp[0];
+    }
+    return tmp;
+  }
+
+  if (op in noCastOps) {
+    return val;
+  }
+  if (op in numberOps) {
+    // Null and undefined not allowed for $pop, $inc
+    if (val == null) {
+      throw new CastError('number', val, schema.path);
+    }
+    if (op === '$inc') {
+      // Support `$inc` with long, int32, etc. (gh-4283)
+      return schema.castForQuery(
+        null,
+        val,
+        context
+      );
+    }
+    try {
+      return castNumber(val);
+    } catch (error) {
+      throw new CastError('number', val, schema.path);
+    }
+  }
+  if (op === '$currentDate') {
+    if (typeof val === 'object') {
+      return { $type: val.$type };
+    }
+    return Boolean(val);
+  }
+
+  if (/^\$/.test($conditional)) {
+    return schema.castForQuery(
+      $conditional,
+      val,
+      context
+    );
+  }
+
+  if (overwriteOps[op]) {
+    const skipQueryCastForUpdate = val != null && schema.$isMongooseArray && schema.$fullPath != null && !schema.$fullPath.match(/\d+$/);
+    const applySetters = schema[schemaMixedSymbol] != null;
+    if (skipQueryCastForUpdate || applySetters) {
+      return schema.applySetters(val, context);
+    }
+    return schema.castForQuery(
+      null,
+      val,
+      context
+    );
+  }
+
+  return schema.castForQuery(null, val, context);
+}

node_modules/mongoose/lib/helpers/query/completeMany.js

@@ -0,0 +1,36 @@
+'use strict';
+
+const helpers = require('../../queryhelpers');
+
+module.exports = completeMany;
+
+/**
+ * Given a model and an array of docs, hydrates all the docs to be instances
+ * of the model. Used to initialize docs returned from the db from `find()`
+ *
+ * @param {Model} model
+ * @param {Array} docs
+ * @param {Object} fields the projection used, including `select` from schemas
+ * @param {Object} userProvidedFields the user-specified projection
+ * @param {Object} [opts]
+ * @param {Array} [opts.populated]
+ * @param {ClientSession} [opts.session]
+ * @param {Function} callback
+ * @api private
+ */
+
+async function completeMany(model, docs, fields, userProvidedFields, opts) {
+  return Promise.all(docs.map(doc => new Promise((resolve, reject) => {
+    const rawDoc = doc;
+    doc = helpers.createModel(model, doc, fields, userProvidedFields);
+    if (opts.session != null) {
+      doc.$session(opts.session);
+    }
+    doc.$init(rawDoc, opts, (err) => {
+      if (err != null) {
+        return reject(err);
+      }
+      resolve(doc);
+    });
+  })));
+}

node_modules/mongoose/lib/helpers/query/getEmbeddedDiscriminatorPath.js

@@ -0,0 +1,90 @@
+'use strict';
+
+const cleanPositionalOperators = require('../schema/cleanPositionalOperators');
+const get = require('../get');
+const getDiscriminatorByValue = require('../discriminator/getDiscriminatorByValue');
+const updatedPathsByArrayFilter = require('../update/updatedPathsByArrayFilter');
+
+/**
+ * Like `schema.path()`, except with a document, because impossible to
+ * determine path type without knowing the embedded discriminator key.
+ * @param {Schema} schema
+ * @param {Object} [update]
+ * @param {Object} [filter]
+ * @param {String} path
+ * @param {Object} [options]
+ * @api private
+ */
+
+module.exports = function getEmbeddedDiscriminatorPath(schema, update, filter, path, options) {
+  const parts = path.split('.');
+  let schematype = null;
+  let type = 'adhocOrUndefined';
+
+  filter = filter || {};
+  update = update || {};
+  const arrayFilters = options != null && Array.isArray(options.arrayFilters) ?
+    options.arrayFilters : [];
+  const updatedPathsByFilter = updatedPathsByArrayFilter(update);
+
+  for (let i = 0; i < parts.length; ++i) {
+    const subpath = cleanPositionalOperators(parts.slice(0, i + 1).join('.'));
+    schematype = schema.path(subpath);
+    if (schematype == null) {
+      continue;
+    }
+
+    type = schema.pathType(subpath);
+    if ((schematype.$isSingleNested || schematype.$isMongooseDocumentArrayElement) &&
+        schematype.schema.discriminators != null) {
+      const key = get(schematype, 'schema.options.discriminatorKey');
+      const discriminatorValuePath = subpath + '.' + key;
+      const discriminatorFilterPath =
+        discriminatorValuePath.replace(/\.\d+\./, '.');
+      let discriminatorKey = null;
+
+      if (discriminatorValuePath in filter) {
+        discriminatorKey = filter[discriminatorValuePath];
+      }
+      if (discriminatorFilterPath in filter) {
+        discriminatorKey = filter[discriminatorFilterPath];
+      }
+
+      const wrapperPath = subpath.replace(/\.\d+$/, '');
+      if (schematype.$isMongooseDocumentArrayElement &&
+          get(filter[wrapperPath], '$elemMatch.' + key) != null) {
+        discriminatorKey = filter[wrapperPath].$elemMatch[key];
+      }
+
+      if (discriminatorValuePath in update) {
+        discriminatorKey = update[discriminatorValuePath];
+      }
+
+      for (const filterKey of Object.keys(updatedPathsByFilter)) {
+        const schemaKey = updatedPathsByFilter[filterKey] + '.' + key;
+        const arrayFilterKey = filterKey + '.' + key;
+        if (schemaKey === discriminatorFilterPath) {
+          const filter = arrayFilters.find(filter => filter.hasOwnProperty(arrayFilterKey));
+          if (filter != null) {
+            discriminatorKey = filter[arrayFilterKey];
+          }
+        }
+      }
+
+      if (discriminatorKey == null) {
+        continue;
+      }
+
+      const discriminatorSchema = getDiscriminatorByValue(schematype.caster.discriminators, discriminatorKey).schema;
+
+      const rest = parts.slice(i + 1).join('.');
+      schematype = discriminatorSchema.path(rest);
+      if (schematype != null) {
+        type = discriminatorSchema._getPathType(rest);
+        break;
+      }
+    }
+  }
+
+  return { type: type, schematype: schematype };
+};

node_modules/mongoose/lib/helpers/query/handleImmutable.js

@@ -0,0 +1,28 @@
+'use strict';
+
+const StrictModeError = require('../../error/strict');
+
+module.exports = function handleImmutable(schematype, strict, obj, key, fullPath, ctx) {
+  if (schematype == null || !schematype.options || !schematype.options.immutable) {
+    return false;
+  }
+  let immutable = schematype.options.immutable;
+
+  if (typeof immutable === 'function') {
+    immutable = immutable.call(ctx, ctx);
+  }
+  if (!immutable) {
+    return false;
+  }
+
+  if (strict === false) {
+    return false;
+  }
+  if (strict === 'throw') {
+    throw new StrictModeError(null,
+      `Field ${fullPath} is immutable and strict = 'throw'`);
+  }
+
+  delete obj[key];
+  return true;
+};

node_modules/mongoose/lib/helpers/query/handleReadPreferenceAliases.js

@@ -0,0 +1,23 @@
+'use strict';
+
+module.exports = function handleReadPreferenceAliases(pref) {
+  switch (pref) {
+    case 'p':
+      pref = 'primary';
+      break;
+    case 'pp':
+      pref = 'primaryPreferred';
+      break;
+    case 's':
+      pref = 'secondary';
+      break;
+    case 'sp':
+      pref = 'secondaryPreferred';
+      break;
+    case 'n':
+      pref = 'nearest';
+      break;
+  }
+
+  return pref;
+};

node_modules/mongoose/lib/helpers/query/hasDollarKeys.js

@@ -0,0 +1,23 @@
+'use strict';
+
+/*!
+ * ignore
+ */
+
+module.exports = function hasDollarKeys(obj) {
+
+  if (typeof obj !== 'object' || obj === null) {
+    return false;
+  }
+
+  const keys = Object.keys(obj);
+  const len = keys.length;
+
+  for (let i = 0; i < len; ++i) {
+    if (keys[i][0] === '$') {
+      return true;
+    }
+  }
+
+  return false;
+};

node_modules/mongoose/lib/helpers/query/isOperator.js

@@ -0,0 +1,14 @@
+'use strict';
+
+const specialKeys = new Set([
+  '$ref',
+  '$id',
+  '$db'
+]);
+
+module.exports = function isOperator(path) {
+  return (
+    path[0] === '$' &&
+    !specialKeys.has(path)
+  );
+};

node_modules/mongoose/lib/helpers/query/sanitizeFilter.js

@@ -0,0 +1,38 @@
+'use strict';
+
+const hasDollarKeys = require('./hasDollarKeys');
+const { trustedSymbol } = require('./trusted');
+
+module.exports = function sanitizeFilter(filter) {
+  if (filter == null || typeof filter !== 'object') {
+    return filter;
+  }
+  if (Array.isArray(filter)) {
+    for (const subfilter of filter) {
+      sanitizeFilter(subfilter);
+    }
+    return filter;
+  }
+
+  const filterKeys = Object.keys(filter);
+  for (const key of filterKeys) {
+    const value = filter[key];
+    if (value != null && value[trustedSymbol]) {
+      continue;
+    }
+    if (key === '$and' || key === '$or') {
+      sanitizeFilter(value);
+      continue;
+    }
+
+    if (hasDollarKeys(value)) {
+      const keys = Object.keys(value);
+      if (keys.length === 1 && keys[0] === '$eq') {
+        continue;
+      }
+      filter[key] = { $eq: filter[key] };
+    }
+  }
+
+  return filter;
+};

node_modules/mongoose/lib/helpers/query/sanitizeProjection.js

@@ -0,0 +1,14 @@
+'use strict';
+
+module.exports = function sanitizeProjection(projection) {
+  if (projection == null) {
+    return;
+  }
+
+  const keys = Object.keys(projection);
+  for (let i = 0; i < keys.length; ++i) {
+    if (typeof projection[keys[i]] === 'string') {
+      projection[keys[i]] = 1;
+    }
+  }
+};

node_modules/mongoose/lib/helpers/query/selectPopulatedFields.js

@@ -0,0 +1,49 @@
+'use strict';
+
+const isExclusive = require('../projection/isExclusive');
+const isInclusive = require('../projection/isInclusive');
+
+/*!
+ * ignore
+ */
+
+module.exports = function selectPopulatedFields(fields, userProvidedFields, populateOptions) {
+  if (populateOptions == null) {
+    return;
+  }
+
+  const paths = Object.keys(populateOptions);
+  userProvidedFields = userProvidedFields || {};
+  if (isInclusive(fields)) {
+    for (const path of paths) {
+      if (!isPathInFields(userProvidedFields, path)) {
+        fields[path] = 1;
+      } else if (userProvidedFields[path] === 0) {
+        delete fields[path];
+      }
+    }
+  } else if (isExclusive(fields)) {
+    for (const path of paths) {
+      if (userProvidedFields[path] == null) {
+        delete fields[path];
+      }
+    }
+  }
+};
+
+/*!
+ * ignore
+ */
+
+function isPathInFields(userProvidedFields, path) {
+  const pieces = path.split('.');
+  const len = pieces.length;
+  let cur = pieces[0];
+  for (let i = 1; i < len; ++i) {
+    if (userProvidedFields[cur] != null || userProvidedFields[cur + '.$'] != null) {
+      return true;
+    }
+    cur += '.' + pieces[i];
+  }
+  return userProvidedFields[cur] != null || userProvidedFields[cur + '.$'] != null;
+}

node_modules/mongoose/lib/helpers/query/trusted.js

@@ -0,0 +1,13 @@
+'use strict';
+
+const trustedSymbol = Symbol('mongoose#trustedSymbol');
+
+exports.trustedSymbol = trustedSymbol;
+
+exports.trusted = function trusted(obj) {
+  if (obj == null || typeof obj !== 'object') {
+    return obj;
+  }
+  obj[trustedSymbol] = true;
+  return obj;
+};

node_modules/mongoose/lib/helpers/query/validOps.js

@@ -0,0 +1,22 @@
+'use strict';
+
+module.exports = Object.freeze([
+  // Read
+  'count',
+  'countDocuments',
+  'distinct',
+  'estimatedDocumentCount',
+  'find',
+  'findOne',
+  // Update
+  'findOneAndReplace',
+  'findOneAndUpdate',
+  'replaceOne',
+  'updateMany',
+  'updateOne',
+  // Delete
+  'deleteMany',
+  'deleteOne',
+  'findOneAndDelete',
+  'findOneAndRemove'
+]);

node_modules/mongoose/lib/helpers/schema/addAutoId.js

@@ -0,0 +1,7 @@
+'use strict';
+
+module.exports = function addAutoId(schema) {
+  const _obj = { _id: { auto: true } };
+  _obj._id[schema.options.typeKey] = 'ObjectId';
+  schema.add(_obj);
+};

node_modules/mongoose/lib/helpers/schema/applyBuiltinPlugins.js

@@ -0,0 +1,12 @@
+'use strict';
+
+const builtinPlugins = require('../../plugins');
+
+module.exports = function applyBuiltinPlugins(schema) {
+  for (const plugin of Object.values(builtinPlugins)) {
+    plugin(schema, { deduplicate: true });
+  }
+  schema.plugins = Object.values(builtinPlugins).
+    map(fn => ({ fn, opts: { deduplicate: true } })).
+    concat(schema.plugins);
+};

node_modules/mongoose/lib/helpers/schema/applyPlugins.js

@@ -0,0 +1,55 @@
+'use strict';
+
+module.exports = function applyPlugins(schema, plugins, options, cacheKey) {
+  if (schema[cacheKey]) {
+    return;
+  }
+  schema[cacheKey] = true;
+
+  if (!options || !options.skipTopLevel) {
+    let pluginTags = null;
+    for (const plugin of plugins) {
+      const tags = plugin[1] == null ? null : plugin[1].tags;
+      if (!Array.isArray(tags)) {
+        schema.plugin(plugin[0], plugin[1]);
+        continue;
+      }
+
+      pluginTags = pluginTags || new Set(schema.options.pluginTags || []);
+      if (!tags.find(tag => pluginTags.has(tag))) {
+        continue;
+      }
+      schema.plugin(plugin[0], plugin[1]);
+    }
+  }
+
+  options = Object.assign({}, options);
+  delete options.skipTopLevel;
+
+  if (options.applyPluginsToChildSchemas !== false) {
+    for (const path of Object.keys(schema.paths)) {
+      const type = schema.paths[path];
+      if (type.schema != null) {
+        applyPlugins(type.schema, plugins, options, cacheKey);
+
+        // Recompile schema because plugins may have changed it, see gh-7572
+        type.caster.prototype.$__setSchema(type.schema);
+      }
+    }
+  }
+
+  const discriminators = schema.discriminators;
+  if (discriminators == null) {
+    return;
+  }
+
+  const applyPluginsToDiscriminators = options.applyPluginsToDiscriminators;
+
+  const keys = Object.keys(discriminators);
+  for (const discriminatorKey of keys) {
+    const discriminatorSchema = discriminators[discriminatorKey];
+
+    applyPlugins(discriminatorSchema, plugins,
+      { skipTopLevel: !applyPluginsToDiscriminators }, cacheKey);
+  }
+};

node_modules/mongoose/lib/helpers/schema/applyWriteConcern.js

@@ -0,0 +1,30 @@
+'use strict';
+
+const get = require('../get');
+
+module.exports = function applyWriteConcern(schema, options) {
+  const writeConcern = get(schema, 'options.writeConcern', {});
+  if (Object.keys(writeConcern).length != 0) {
+    options.writeConcern = {};
+    if (!('w' in options) && writeConcern.w != null) {
+      options.writeConcern.w = writeConcern.w;
+    }
+    if (!('j' in options) && writeConcern.j != null) {
+      options.writeConcern.j = writeConcern.j;
+    }
+    if (!('wtimeout' in options) && writeConcern.wtimeout != null) {
+      options.writeConcern.wtimeout = writeConcern.wtimeout;
+    }
+  }
+  else {
+    if (!('w' in options) && writeConcern.w != null) {
+      options.w = writeConcern.w;
+    }
+    if (!('j' in options) && writeConcern.j != null) {
+      options.j = writeConcern.j;
+    }
+    if (!('wtimeout' in options) && writeConcern.wtimeout != null) {
+      options.wtimeout = writeConcern.wtimeout;
+    }
+  }
+};

node_modules/mongoose/lib/helpers/schema/cleanPositionalOperators.js

@@ -0,0 +1,12 @@
+'use strict';
+
+/**
+ * For consistency's sake, we replace positional operator `$` and array filters
+ * `$[]` and `$[foo]` with `0` when looking up schema paths.
+ */
+
+module.exports = function cleanPositionalOperators(path) {
+  return path.
+    replace(/\.\$(\[[^\]]*\])?(?=\.)/g, '.0').
+    replace(/\.\$(\[[^\]]*\])?$/g, '.0');
+};

node_modules/mongoose/lib/helpers/schema/getIndexes.js

@@ -0,0 +1,164 @@
+'use strict';
+
+const get = require('../get');
+const helperIsObject = require('../isObject');
+const decorateDiscriminatorIndexOptions = require('../indexes/decorateDiscriminatorIndexOptions');
+
+/**
+ * Gather all indexes defined in the schema, including single nested,
+ * document arrays, and embedded discriminators.
+ * @param {Schema} schema
+ * @api private
+ */
+
+module.exports = function getIndexes(schema) {
+  let indexes = [];
+  const schemaStack = new WeakMap();
+  const indexTypes = schema.constructor.indexTypes;
+  const indexByName = new Map();
+
+  collectIndexes(schema);
+  return indexes;
+
+  function collectIndexes(schema, prefix, baseSchema) {
+    // Ignore infinitely nested schemas, if we've already seen this schema
+    // along this path there must be a cycle
+    if (schemaStack.has(schema)) {
+      return;
+    }
+    schemaStack.set(schema, true);
+
+    prefix = prefix || '';
+    const keys = Object.keys(schema.paths);
+
+    for (const key of keys) {
+      const path = schema.paths[key];
+      if (baseSchema != null && baseSchema.paths[key]) {
+        // If looking at an embedded discriminator schema, don't look at paths
+        // that the
+        continue;
+      }
+
+      if (path.$isMongooseDocumentArray || path.$isSingleNested) {
+        if (get(path, 'options.excludeIndexes') !== true &&
+            get(path, 'schemaOptions.excludeIndexes') !== true &&
+            get(path, 'schema.options.excludeIndexes') !== true) {
+          collectIndexes(path.schema, prefix + key + '.');
+        }
+
+        if (path.schema.discriminators != null) {
+          const discriminators = path.schema.discriminators;
+          const discriminatorKeys = Object.keys(discriminators);
+          for (const discriminatorKey of discriminatorKeys) {
+            collectIndexes(discriminators[discriminatorKey],
+              prefix + key + '.', path.schema);
+          }
+        }
+
+        // Retained to minimize risk of backwards breaking changes due to
+        // gh-6113
+        if (path.$isMongooseDocumentArray) {
+          continue;
+        }
+      }
+
+      const index = path._index || (path.caster && path.caster._index);
+
+      if (index !== false && index !== null && index !== undefined) {
+        const field = {};
+        const isObject = helperIsObject(index);
+        const options = isObject ? index : {};
+        const type = typeof index === 'string' ? index :
+          isObject ? index.type :
+            false;
+
+        if (type && indexTypes.indexOf(type) !== -1) {
+          field[prefix + key] = type;
+        } else if (options.text) {
+          field[prefix + key] = 'text';
+          delete options.text;
+        } else {
+          const isDescendingIndex = Number(index) === -1;
+          field[prefix + key] = isDescendingIndex ? -1 : 1;
+        }
+
+        delete options.type;
+        if (!('background' in options)) {
+          options.background = true;
+        }
+        if (schema.options.autoIndex != null) {
+          options._autoIndex = schema.options.autoIndex;
+        }
+
+        const indexName = options && options.name;
+
+        if (typeof indexName === 'string') {
+          if (indexByName.has(indexName)) {
+            Object.assign(indexByName.get(indexName), field);
+          } else {
+            indexes.push([field, options]);
+            indexByName.set(indexName, field);
+          }
+        } else {
+          indexes.push([field, options]);
+          indexByName.set(indexName, field);
+        }
+      }
+    }
+
+    schemaStack.delete(schema);
+
+    if (prefix) {
+      fixSubIndexPaths(schema, prefix);
+    } else {
+      schema._indexes.forEach(function(index) {
+        const options = index[1];
+        if (!('background' in options)) {
+          options.background = true;
+        }
+        decorateDiscriminatorIndexOptions(schema, options);
+      });
+      indexes = indexes.concat(schema._indexes);
+    }
+  }
+
+  /**
+   * Checks for indexes added to subdocs using Schema.index().
+   * These indexes need their paths prefixed properly.
+   *
+   * schema._indexes = [ [indexObj, options], [indexObj, options] ..]
+   * @param {Schema} schema
+   * @param {String} prefix
+   * @api private
+   */
+
+  function fixSubIndexPaths(schema, prefix) {
+    const subindexes = schema._indexes;
+    const len = subindexes.length;
+    for (let i = 0; i < len; ++i) {
+      const indexObj = subindexes[i][0];
+      const indexOptions = subindexes[i][1];
+      const keys = Object.keys(indexObj);
+      const klen = keys.length;
+      const newindex = {};
+
+      // use forward iteration, order matters
+      for (let j = 0; j < klen; ++j) {
+        const key = keys[j];
+        newindex[prefix + key] = indexObj[key];
+      }
+
+      const newIndexOptions = Object.assign({}, indexOptions);
+      if (indexOptions != null && indexOptions.partialFilterExpression != null) {
+        newIndexOptions.partialFilterExpression = {};
+        const partialFilterExpression = indexOptions.partialFilterExpression;
+        for (const key of Object.keys(partialFilterExpression)) {
+          newIndexOptions.partialFilterExpression[prefix + key] =
+            partialFilterExpression[key];
+        }
+      }
+
+      indexes.push([newindex, newIndexOptions]);
+    }
+  }
+};

node_modules/mongoose/lib/helpers/schema/getKeysInSchemaOrder.js

@@ -0,0 +1,28 @@
+'use strict';
+
+const get = require('../get');
+
+module.exports = function getKeysInSchemaOrder(schema, val, path) {
+  const schemaKeys = path != null ? Object.keys(get(schema.tree, path, {})) : Object.keys(schema.tree);
+  const valKeys = new Set(Object.keys(val));
+
+  let keys;
+  if (valKeys.size > 1) {
+    keys = new Set();
+    for (const key of schemaKeys) {
+      if (valKeys.has(key)) {
+        keys.add(key);
+      }
+    }
+    for (const key of valKeys) {
+      if (!keys.has(key)) {
+        keys.add(key);
+      }
+    }
+    keys = Array.from(keys);
+  } else {
+    keys = Array.from(valKeys);
+  }
+
+  return keys;
+};