command events are not fired after setting monitorCommands: true

[bobeZzz]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

8.4.0

Node.js version

18.19.1

MongoDB server version

6.0.1

Typescript version (if applicable)

No response

Description

MongoDB dirver supports Command Monitoring

Problem: unable to subscribe for command monitoring events using mongoose

Steps to Reproduce

using mongoose@8.4.0
After following setup steps from the doc above, events are not emitted / reaching event listeners

const mongoose = require('mongoose');

const initMongoose = async () => {
  await mongoose.connect(
    'mongodb://localhost:27017/mydatabase',
    {
      monitorCommands: true,
    }
  );

  const db = mongoose.connection;
  db.on('commandStarted', event => console.log(event));
  db.on('commandFailed', event => console.log(event));
  db.on('commandSucceeded', event => console.log(event));
}

const User = mongoose.model('User', new mongoose.Schema({
  name: String,
  email: String,
  age: Number,
}));

const main = async () => {
  await initMongoose();
  await User.findOne()
  console.log('done!')
}

main()

Expected Behavior

but when using mongodb@6.6.2 directly which is installed together with mongoose@8.4.0
Events are fired and able to reach event listeners

const { MongoClient } = require("mongodb");

const client = new MongoClient(
  'mongodb://localhost:27017/mydatabase',
  { monitorCommands: true }
);

client.on('commandStarted', event => console.log(event));
client.on('commandFailed', event => console.log(event));
client.on('commandSucceeded', event => console.log(event));

async function main() {
  try {
    await client
      .db("mydatabase")
      .collection('users1')
      .findOne()
  } finally {
    await client.close();
  }
}
main()

[vkarpov15]

Use the following instead:

  const client = mongoose.connection.client;
  client.on('commandStarted', event => console.log(event));
  client.on('commandFailed', event => console.log(event));
  client.on('commandSucceeded', event => console.log(event));

Connection.prototype.client contains the Mongoose connection's MongoClient instance, so that is what you should use to integrate with the MongoDB Node driver directly.

That being said, we will keep this issue open for 8.5 because it would by nice for Mongoose to bubble up the monitorCommands events onto the Mongoose connection.

[bobeZzz]

thanks, works like a charm!
just an FYI mongoose.connection.client doesn't seem to be declared on TS side of things, but there is a method availabel to retrieve client instance mongoose.connection.getClient() which covers it.

[vkarpov15]

Yeah connection.getClient() is equivalent to connection.client