Using watch only sends insertion events, not delete or update

[AlexanderEpolite]

Prerequisites

• I have written a descriptive issue title

Mongoose version

8.3.1

Node.js version

20

MongoDB version

7.0.8

Operating system

Linux

Operating system version (i.e. 20.04, 11.3, 10)

Ubuntu 22.04

Issue

The following code is only logging when an insertion event happens; however, delete and update events are not being sent in the "change" listener.

Let me know if I'm doing something wrong.

const s = Member.watch([
    {
        $match: {"fullDocument.user_id": user_id, "operationType": {$in: ["insert", "update", "delete"]}},
    }
]);

s.on("change", (change) => {
    console.log(change);
});

[FaizBShah]

If you remove the options object in the watch() function, is it working?

[AlexanderEpolite]

If you remove the options object in the watch() function, is it working?

@FaizBShah it works when I have this:

const s = Member.watch();

But not with this:

const s = Member.watch([
    {
        $match: {"fullDocument.user_id": user_id},
    }
]);

Any clue what might be causing it? I'm probably going to just switch to once watch stream anyways to save resources.

[FaizBShah]

@AlexanderEpolite Im not too familiar with the type of the argument passed in the .watch() function, but according to this doc, the operationType field should be in the second object, not in the first. Basically, the issue is with the incorrect object structure of the argument.

[IslandRhythms]

const mongoose = require('mongoose');

const testSchema = new mongoose.Schema({
  user_id: mongoose.Schema.Types.ObjectId,
  name: String
});


const Test = mongoose.model('Test', testSchema);

async function run() {
  await mongoose.connect(process.env.MONGOOSECONNECTIONSTRING);
  await mongoose.connection.dropDatabase();
  const userId = new mongoose.Types.ObjectId();
  const s = Test.watch([
    {
      $match: {"fullDocument.user_id": userId },
    }
  ]);

  s.on('change', (change) => console.log('change', change))

  const doc = await Test.create({
    user_id: userId,
    name: 'Test Testerson'
  });

  const res = await Test.updateOne({ _id: doc._id }, { name: 'Test' });
  console.log('what is res', res);
  console.log('done');
}

run();

[vkarpov15]

This is expected behavior, you need to set the fullDocument option to watch() in order for the fullDocument property to show up on updates and deletes. Use the following syntax:

const s = Member.watch([
    {
        $match: {"fullDocument.user_id": user_id, "operationType": {$in: ["insert", "update", "delete"]}},
    }
], { fullDocument: 'updateLookup' });