fix(mongoose): support mongoose.set('autoIndex', false)

Fix #8158

lib/index.js

@@ -158,6 +158,7 @@ Mongoose.prototype.driver = require('./driver');
  * - 'strict': true by default, may be `false`, `true`, or `'throw'`. Sets the default strict mode for schemas.
  * - 'selectPopulatedPaths': true by default. Set to false to opt out of Mongoose adding all fields that you `populate()` to your `select()`. The schema-level option `selectPopulatedPaths` overwrites this one.
  * - 'maxTimeMS': If set, attaches [maxTimeMS](https://docs.mongodb.com/manual/reference/operator/meta/maxTimeMS/) to every query
+ * - 'autoIndex': true by default. Set to false to disable automatic index creation for all models associated with this Mongoose instance.
  *
  * @param {String} key
  * @param {String|Function|Boolean} value

lib/model.js

@@ -1184,9 +1184,8 @@ Model.init = function init(callback) {
   }
 
   const Promise = PromiseProvider.get();
-  const autoIndex = this.schema.options.autoIndex == null ?
-    this.db.config.autoIndex :
-    this.schema.options.autoIndex;
+  const autoIndex = utils.getOption('autoIndex',
+    this.schema.options, this.db.config, this.db.base.options);
   const autoCreate = this.schema.options.autoCreate == null ?
     this.db.config.autoCreate :
     this.schema.options.autoCreate;

lib/utils.js

@@ -1072,6 +1072,22 @@ exports.each = function(arr, fn) {
   }
 };
 
+/*!
+ * ignore
+ */
+
+exports.getOption = function(name) {
+  const sources = Array.prototype.slice.call(arguments, 1);
+
+  for (const source of sources) {
+    if (source[name] != null) {
+      return source[name];
+    }
+  }
+
+  return null;
+};
+
 /*!
  * ignore
  */