DeprecationWarning: Listening to events on the Db class has been deprecated and will be removed in the next major version

[Systerr]

Do you want to request a feature or report a bug?
bug (deprecation warning)

What is the current behavior?
On start we have deprecation warning into console

If the current behavior is a bug, please provide the steps to reproduce.

(node:9455) DeprecationWarning: Listening to events on the Db class has been deprecated and will be removed in the next major version.
    at _setClient (node_modules/mongoose/lib/connection.js:943:6)
    at node_modules/mongoose/lib/connection.js:839:7
    at node_modules/mongodb/lib/utils.js:693:5
    at node_modules/mongodb/lib/mongo_client.js:227:7
    at connectCallback (node_modules/mongodb/lib/operations/connect.js:366:5)
    at node_modules/mongodb/lib/operations/connect.js:602:5
    at Object.connectHandler [as callback] (/node_modules/mongodb/lib/core/sdam/topology.js:297:43)
    at processWaitQueue (node_modules/mongodb/lib/core/sdam/topology.js:1048:21)
    at NativeTopology.serverUpdateHandler (node_modules/mongodb/lib/core/sdam/topology.js:567:7)
    at Server.emit (events.js:315:20)

What is the expected behavior?
No deprecation warning
What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.
Latest 5.11.16

I digged in into warning and found why this happens:

1. This introduced into mongo driver on version v3.6.4 refactor: deprecate Db.on and Db.once mongodb/node-mongodb-native#2610 as part on preparation of driver v4 release
2. Latest mongoose 5.11.16 introduced mongo drive update Upgrade mongodb driver to 3.6.4 #9893
3. Original change happens because of refactor(db)!: suppress Db events mongodb/node-mongodb-native#2251

[Systerr]

https://github.com/Automattic/mongoose/blob/5.11.16/lib/connection.js#L943

[pnutmath]

https://jira.mongodb.org/browse/NODE-1709?focusedCommentId=2962047&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-2962047

Only MongoClient will receive events not DB class in future

[purpshell]

how does this get fixed?

[lantw44]

The warning still exists in mongoose 5.11.18:

(node:90089) DeprecationWarning: Listening to events on the Db class has been deprecated and will be removed in the next major version.
    at _setClient (node_modules/mongoose/lib/connection.js:932:10)
    at node_modules/mongoose/lib/connection.js:838:7
    at node_modules/mongodb/lib/utils.js:693:5
    at node_modules/mongodb/lib/mongo_client.js:227:7
    at connectCallback (node_modules/mongodb/lib/operations/connect.js:366:5)
    at node_modules/mongodb/lib/operations/connect.js:602:5
    at connectHandler (node_modules/mongodb/lib/core/sdam/topology.js:297:43)
    at cb (node_modules/mongodb/lib/core/sdam/topology.js:681:26)
    at node_modules/mongodb/lib/cmap/connection_pool.js:350:13
    at handleOperationResult (node_modules/mongodb/lib/core/sdam/server.js:558:5)
    at MessageStream.messageHandler (node_modules/mongodb/lib/cmap/connection.js:277:5)
    at MessageStream.emit (events.js:315:20)
    at MessageStream.EventEmitter.emit (domain.js:529:15)
    at processIncomingData (node_modules/mongodb/lib/cmap/message_stream.js:144:12)
    at MessageStream._write (node_modules/mongodb/lib/cmap/message_stream.js:42:5)
    at writeOrBuffer (internal/streams/writable.js:358:12)

[troykelly]

@vkarpov15 can this please be reopened until it's confirmed resolved?

[vkarpov15]

@lantw44 @troykelly do you have useUnifiedTopology: true set?

[lantw44]

@lantw44 @troykelly do you have useUnifiedTopology: true set?

Yes, useUnifiedTopology: true is set when calling mongoose.createConnection.

[vkarpov15]

I'm unable to repro, the below script doesn't print any warnings for me. Can you please modify the below script to demonstrate your issue?

'use strict';
  
const mongoose = require('mongoose');

mongoose.set('useFindAndModify', false);

const { Schema } = mongoose;

run().catch(err => console.log(err));

async function run() {
  await mongoose.createConnection('mongodb://localhost:27017/test', {
    useNewUrlParser: true,
    useUnifiedTopology: true
  });

  console.log('Done');
}

[FlorentinTh]

@vkarpov15 just replacing your connection string from localhost to an instance of MongoDB Atlas in your script fires the warning like so :

mongodb+srv://<username>:<password>@cluster-ign8c.mongodb.net/test?retryWrites=true&w=majority

So maybe the issue is not related to Mongoose ?!

[Unknow1002]

This link may help you:
https://stackoverflow.com/questions/66190532/deprecationwarning-listening-to-events-on-the-db-class-has-been-deprecated-and

[tukusejssirs]

This happens to me connecting to new database (const newDb = await mongoose.connection.useDb('newDb')), while I am already connected to a different database; see #8267.

Note: I am connected to a local, fresh database, therefore it is not only connected to Mongo Altas databases.

[vkarpov15]

@tukusejssirs the below script doesn't print any warnings. Please modify the below script to demonstrate your issue:

'use strict';
  
const mongoose = require('mongoose');

mongoose.set('useFindAndModify', false);

const { Schema } = mongoose;

run().catch(err => console.log(err));

async function run() {
  await mongoose.createConnection('mongodb://localhost:27017/test', {
    useNewUrlParser: true,
    useUnifiedTopology: true
  });


  const newDb = await mongoose.connection.useDb('newDb');

  console.log('Done');
}

@FlorentinTh I tried with my Atlas cluster and I don't get any warning:

  await mongoose.createConnection('mongodb+srv://OMITTED:[email protected]/myFirstDatabase?retryWrites=true&w=majority', {
    useNewUrlParser: true,
    useUnifiedTopology: true
  });

I'm going to close this issue. If you're still seeing this warning:

1. Please make sure you've upgraded to the latest version of Mongoose, v5.12.3 as of this writing.
2. If that doesn't fix the issue, please open a new issue and follow the issue template.