"MongoDB删除用户时删除用户创建的所有文档"

Question

I'm working on MongoDB (mongoose) and NodeJS. I have a problem. I'm makine a RESTful API. I have Users model (collection) and Comments model (collection). Users creates comments, and i relate the User and User's Comments with User's _id. l want to delete all comments when user deleted. How can I make this in MongoDB? I search it on Google for 2 days but İ l can't find a good source, looked at MongoDB Manual Documents, but i didn't find anything.

Answer 1

MongoDB doesn't support built-in relations and transactions among collections.

To remove related Comments (I suppose you have userId field in each Comment ):

db.comments.remove({userId: removedUserId})

If you have collection of ids of comments in User, then:

db.comments.remove({id: {$in: collectionOfCommentIds}})

---

Mongoose does support middlewares . But notice that

There is no query hook for remove(), only for documents.

So you can define remove hook for use with user.remove() . But not for User.remove({_id: userId})

userSchema.post(`remove`, (user) => {
    Comments.remove({userId: user._id})
})

Answer 2

If you are using parent referencing

    userSchema.post('findOneAndDelete', async id => {
      await Comments.deleteMany({ user: id });
    });