some progress

node_modules/mongoose/lib/helpers/update/moveImmutableProperties.js

@@ -0,0 +1,53 @@
+'use strict';
+
+const get = require('../get');
+
+/**
+ * Given an update, move all $set on immutable properties to $setOnInsert.
+ * This should only be called for upserts, because $setOnInsert bypasses the
+ * strictness check for immutable properties.
+ */
+
+module.exports = function moveImmutableProperties(schema, update, ctx) {
+  if (update == null) {
+    return;
+  }
+
+  const keys = Object.keys(update);
+  for (const key of keys) {
+    const isDollarKey = key.startsWith('$');
+
+    if (key === '$set') {
+      const updatedPaths = Object.keys(update[key]);
+      for (const path of updatedPaths) {
+        _walkUpdatePath(schema, update[key], path, update, ctx);
+      }
+    } else if (!isDollarKey) {
+      _walkUpdatePath(schema, update, key, update, ctx);
+    }
+
+  }
+};
+
+function _walkUpdatePath(schema, op, path, update, ctx) {
+  const schematype = schema.path(path);
+  if (schematype == null) {
+    return;
+  }
+
+  let immutable = get(schematype, 'options.immutable', null);
+  if (immutable == null) {
+    return;
+  }
+  if (typeof immutable === 'function') {
+    immutable = immutable.call(ctx, ctx);
+  }
+
+  if (!immutable) {
+    return;
+  }
+
+  update.$setOnInsert = update.$setOnInsert || {};
+  update.$setOnInsert[path] = op[path];
+  delete op[path];
+}