Avoid "current URL string parser is deprecated" warning by setting useNewUrlParser to true

Check your mongo version:

mongo --version

If you are using version >= 3.1.0, change your mongo connection file to ->

MongoClient.connect("mongodb://localhost:27017/YourDB", { useNewUrlParser: true })

or your mongoose connection file to ->

mongoose.connect("mongodb://localhost:27017/YourDB", { useNewUrlParser: true });

Ideally, it's a version 4 feature, but v3.1.0 and above are supporting it too. Check out MongoDB GitHub for details.

As noted the 3.1.0-beta4 release of the driver got "released into the wild" a little early by the looks of things. The release is part of work in progress to support newer features in the MongoDB 4.0 upcoming release and make some other API changes.

One such change triggering the current warning is the useNewUrlParser option, due to some changes around how passing the connection URI actually works. More on that later.

Until things "settle down", it would probably be advisable to "pin" at least to the minor version for 3.0.x releases:

  "dependencies": {    "mongodb": "~3.0.8"  }

That should stop the 3.1.x branch being installed on "fresh" installations to node modules. If you already did install a "latest" release which is the "beta" version, then you should clean up your packages ( and package-lock.json ) and make sure you bump that down to a 3.0.x series release.

As for actually using the "new" connection URI options, the main restriction is to actually include the port on the connection string:

const { MongoClient } = require("mongodb");const uri = 'mongodb://localhost:27017';  // mongodb://localhost - will fail(async function() {  try {    const client = await MongoClient.connect(uri,{ useNewUrlParser: true });    // ... anything    client.close();  } catch(e) {    console.error(e)  }})()

That's a more "strict" rule in the new code. The main point being that the current code is essentially part of the "node-native-driver" ( npm mongodb ) repository code, and the "new code" actually imports from the mongodb-core library which "underpins" the "public" node driver.

The point of the "option" being added is to "ease" the transition by adding the option to new code so the newer parser ( actually based around url ) is being used in code adding the option and clearing the deprecation warning, and therefore verifying that your connection strings passed in actually comply with what the new parser is expecting.

In future releases the 'legacy' parser would be removed and then the new parser will simply be what is used even without the option. But by that time, it is expected that all existing code had ample opportunity to test their existing connection strings against what the new parser is expecting.

So if you want to start using new driver features as they are released, then use the available beta and subsequent releases and ideally make sure you are providing a connection string which is valid for the new parser by enabling the useNewUrlParser option in MongoClient.connect().

If you don't actually need access to features related to preview of the MongoDB 4.0 release, then pin the version to a 3.0.x series as noted earlier. This will work as documented and "pinning" this ensures that 3.1.x releases are not "updated" over the expected dependency until you actually want to install a stable version.

The below highlighted code to the mongoose connection solved the warning for the mongoose driver:

mongoose.connect('mongodb://localhost:27017/test', { useNewUrlParser: true });