How to avoid save conflict in mongoose?

Save conflict is when 2 persons are saving the same document. For example, Person A and Person B open the same document. Person A saves the document, followed by Person B, then Person A's data over-write by Person B.

To avoid this, you can use either version check or document lock mechanism.

Version Check:

By default, when you save the document using mongoose, mongoose saves the version number in __v field. We can use the field to do version check to avoid save conflict.

Person A opens and edits the version 1 document. Meantime, Person B also opens the edit version 1 document.

Person A success save the document using below query:

posts.update({ _id: postId, __v: versionNumber } , { $set: { 'comments': updatedText }})

When Person B try to save the document using the same query, the save will be failed because of the wrong version number.

Document Lock:

Locking when Person A edit the document, saved a lock flag to the document.

When person B tries to edit the same document, the system will prompt saying the document is currently edit (lock) by Person A.

Bonus:

If you don’t want to use versioning in your schema you can disable it by passing false for the versionKey option. 

schema.set('versionKey', false);