How to Connect to MongoDB in Node.js: Simple Guide

To connect to MongoDB in Node.js, use the official mongodb package and create a MongoClient with your connection string. Then call connect() on the client to establish the connection before performing database operations.

Syntax

Here is the basic syntax to connect to MongoDB using the official mongodb Node.js driver:

• Import the MongoClient class from the mongodb package.
• Create a new MongoClient instance with your MongoDB connection URI.
• Call the asynchronous connect() method on the client to open the connection.
• Use the client to access databases and collections.
• Close the connection when done.

javascript

import { MongoClient } from 'mongodb';

const uri = 'your-mongodb-connection-string';
const client = new MongoClient(uri);

async function run() {
  try {
    await client.connect();
    // Use client.db() to access database
  } finally {
    await client.close();
  }
}

run().catch(console.dir);

Example

This example shows how to connect to a MongoDB database, list the database names, and then close the connection.

javascript

import { MongoClient } from 'mongodb';

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

async function run() {
  try {
    await client.connect();
    console.log('Connected successfully to MongoDB');

    const databasesList = await client.db().admin().listDatabases();
    console.log('Databases:');
    databasesList.databases.forEach(db => console.log(` - ${db.name}`));
  } catch (err) {
    console.error('Connection error:', err);
  } finally {
    await client.close();
    console.log('Connection closed');
  }
}

run();

Output

Connected successfully to MongoDB
Databases:
 - admin
 - config
 - local
Connection closed

Common Pitfalls

Common mistakes when connecting to MongoDB in Node.js include:

• Not awaiting client.connect(), which causes operations to fail because the connection is not ready.
• Using an incorrect or malformed connection string URI.
• Forgetting to close the connection with client.close(), which can cause resource leaks.
• Not handling errors with try/catch around async calls.

javascript

import { MongoClient } from 'mongodb';

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

// Wrong: Not awaiting connect
client.connect();

// Right: Await connect inside async function
async function run() {
  try {
    await client.connect();
    // operations
  } finally {
    await client.close();
  }
}

run().catch(console.error);

Quick Reference

Tips for connecting to MongoDB in Node.js:

• Use the official mongodb package from npm.
• Always await client.connect() before database operations.
• Use try/catch to handle connection errors gracefully.
• Close the connection with client.close() when done.
• Store your MongoDB URI securely, never hardcode sensitive credentials.

Key Takeaways

Use the official mongodb package and create a MongoClient with your connection URI.

Always await client.connect() before performing database operations.

Handle errors with try/catch to avoid crashes.

Close the connection with client.close() to free resources.

Keep your connection string secure and never expose credentials in code.