fix(model): skip createCollection() in syncIndexes() if autoCreate: f…

…alse

lib/model.js

@@ -1246,19 +1246,21 @@ Model.syncIndexes = async function syncIndexes(options) {
     throw new MongooseError('Model.syncIndexes() no longer accepts a callback');
   }
 
-  const model = this;
+  const autoCreate = options?.autoCreate ?? this.schema.options?.autoCreate ?? this.db.config.autoCreate ?? true;
 
-  try {
-    await model.createCollection();
-  } catch (err) {
-    if (err != null && (err.name !== 'MongoServerError' || err.code !== 48)) {
-      throw err;
+  if (autoCreate) {
+    try {
+      await this.createCollection();
+    } catch (err) {
+      if (err != null && (err.name !== 'MongoServerError' || err.code !== 48)) {
+        throw err;
+      }
     }
   }
 
-  const diffIndexesResult = await model.diffIndexes();
-  const dropped = await model.cleanIndexes({ ...options, toDrop: diffIndexesResult.toDrop });
-  await model.createIndexes({ ...options, toCreate: diffIndexesResult.toCreate });
+  const diffIndexesResult = await this.diffIndexes();
+  const dropped = await this.cleanIndexes({ ...options, toDrop: diffIndexesResult.toDrop });
+  await this.createIndexes({ ...options, toCreate: diffIndexesResult.toCreate });
 
   return dropped;
 };

test/model.test.js

@@ -4885,6 +4885,28 @@ describe('Model', function() {
         assert.deepStrictEqual(indexes.map(index => index.name), ['_id_', 'name_1']);
       });
 
+      it('avoids creating collection if autoCreate: false', async() => {
+        const collectionName = generateRandomCollectionName();
+        const userSchema = new Schema(
+          { name: { type: String, index: true } },
+          { autoIndex: false, autoCreate: false, collation: { locale: 'en_US', strength: 2 } }
+        );
+        const User = db.model('User', userSchema, collectionName);
+
+        // Act
+        await User.syncIndexes();
+
+        // Assert
+        const indexes = await User.listIndexes();
+        assert.deepStrictEqual(indexes.map(index => index.name), ['_id_', 'name_1']);
+
+        const collections = await User.db.listCollections();
+        const collection = collections.find(c => c.name === collectionName);
+        assert.ok(collection);
+        // Collation was not applied because autoCreate was false, so Mongoose did not send `createCollection()`
+        assert.ok(!collection.options.collation);
+      });
+
       it('drops indexes that are not present in schema', async() => {
         // Arrange
         const collectionName = generateRandomCollectionName();