How to filter mongoose changeStream - node.js

Question

I'm working on a chat system, and I try to use the changeStream of mongoDB / mongoose.
I only want to get document if the current user is the recipient, but It not works. So far I have met two cases. One never trigger and the other returned with all documents even if not the current user is the recipient.
The difference is the pipeline in an array or not.
Do you have any idea what is the right syntax?
I read all article that I found in google at the first 10 page in the last 2 days, but none of it contain how to filter. As I understand the aggregation pipe is only for manipulate the result, but its not possible to exclude documents that not pass the conditions.
here is what I have done:
const pipeline = [{
$match: {
"userId": this.recipient.id,
"recipientId": this.user.id
}
}]
const stream = MessageModel.watch(pipeline )
stream.on('change', (data: any) => {
console.log(`messages changed`);
this.socketIo.sockets.in(this.socket.id).emit(`protected/message/subscribe/${this.msg.msgId}`, data.fullDocument);
});

Answer 1

this might be useful
const { ReplSet } = require('mongodb-topology-manager');
const mongoose = require('mongoose');
run().catch(error => console.error(error));
async function run() {
console.log(new Date(), 'start');
const bind_ip = 'localhost';
// Starts a 3-node replica set on ports 31000, 31001, 31002, replica set
// name is "rs0".
const replSet = new ReplSet('mongod', [
{ options: { port: 31000, dbpath: `${__dirname}/data/db/31000`, bind_ip } },
{ options: { port: 31001, dbpath: `${__dirname}/data/db/31001`, bind_ip } },
{ options: { port: 31002, dbpath: `${__dirname}/data/db/31002`, bind_ip } }
], { replSet: 'rs0' });
// Initialize the replica set
await replSet.purge();
await replSet.start();
console.log(new Date(), 'Replica set started...');
// Connect to the replica set
const uri = 'mongodb://localhost:31000,localhost:31001,localhost:31002/' +
'test?replicaSet=rs0';
await mongoose.connect(uri);
// To work around "MongoError: cannot open $changeStream for non-existent
// database: test" for this example
await mongoose.connection.createCollection('people');
const Person = mongoose.model('Person', new mongoose.Schema({ name: String }));
// Create a change stream. The 'change' event gets emitted when there's a
// change in the database
Person.watch().
on('change', data => console.log(new Date(), data));
// Insert a doc, will trigger the change stream handler above
console.log(new Date(), 'Inserting doc');
await Person.create({ name: 'Axl Rose' });
console.log(new Date(), 'Inserted doc');
}