some progress

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);
+  }
+};