Choose a Connection Target

Overview

In this guide, you can learn how to use a connection string and a MongoClient object to connect to different types of MongoDB deployments.

Atlas

To connect to a MongoDB deployment on Atlas, include the following elements in your connection string:

• URL of your Atlas cluster

• MongoDB username

• MongoDB password

Then, pass your connection string to the MongoClient constructor.

When you connect to Atlas, we recommend using the Stable API client option to avoid breaking changes when Atlas upgrades to a new version of MongoDB Server. To learn more about the Stable API feature, see the Stable API guide.

The following code shows how to use the Node.js driver to connect to an Atlas cluster. The code also uses the server_api field to specify a Stable API version.

const { MongoClient, ServerApiVersion } = require("mongodb");
// Replace the placeholder with your Atlas connection string
const uri = "<connection string>";
// Creates a MongoClient with a MongoClientOptions object to set the Stable API version
const client = new MongoClient(uri,  {
        serverApi: {
            version: ServerApiVersion.v1,
            strict: true,
            deprecationErrors: true,
        }
    }
);
async function run() {
  try {
    // Connects the client to the server (optional starting in v4.7)
    await client.connect();
    // Sends a ping to confirm a successful connection
    await client.db("admin").command({ ping: 1 });
    console.log("Pinged your deployment. You successfully connected to MongoDB!");
  } finally {
    // Ensures that the client will close when you finish/error
    await client.close();
  }
}
run().catch(console.dir);

Local Deployments

To connect to a local standalone MongoDB deployment, specify the host of the server. Optionally, specify the port of the server. If no port is specified, the default port is 27017.

You can specify the host and port to connect to by using a connection string, as shown in the following code:

const client = new MongoClient("mongodb://host1:27017");

You can also specify your host as localhost. The following code example connects to localhost on the specified port:

const client = new MongoClient("mongodb://localhost:27017");

Replica Sets

To connect to a replica set, we recommend that you specify all nodes that are part of the replica set. If one or more nodes becomes unavailable, specifying all nodes allows the driver to still connect to the replica set if one node is available.

However, it is sufficient to pass the address of any one node in the replica set to the driver. The node does not need to be the primary, and it may be a hidden node. The driver will then automatically discover the remaining nodes.

The following example shows how to connect to the replica set by using a connection string and how to verify the replica set name on connection by using the replicaSet connection string option:

const client = new MongoClient("mongodb://host1:27017,host2:27017,host3:27017/?replicaSet=myRs");

API Documentation

To learn more about creating a MongoClient object with the Node.js driver, see the API documentation for MongoClient .