Node.js - Connect to MongoDB - Example

Node.js Connect to MongoDB

Node.js Connect to MongoDB – In this Node.js Tutorial, we shall learn to connect to MongoDB from Node.js Application.

The prerequisite to connect to a MongoDB, is having MongoDB installed in the computer. If you have not installed MongoDB yet, refer this tutorial – Install MongoDB.

Steps to Connect to MongoDB via Node.js

To connect to MongoDB from Node.js Application, following is a step by step guide.

Step 1: Start MongoDB service.

Run the following command to start MongoDB Service.

sudo service mongod start

Step 2: Install mongodb package using npm (if not installed already).

arjun@nodejs:~/workspace/nodejs/mongodb$ npm install mongodb
npm WARN saveError ENOENT: no such file or directory, open '/home/arjun/workspace/nodejs/package.json'
npm WARN enoent ENOENT: no such file or directory, open '/home/arjun/workspace/nodejs/package.json'
npm WARN nodejs No description
npm WARN nodejs No repository field.
npm WARN nodejs No README data
npm WARN nodejs No license field.

+ mongodb@2.2.33
added 9 packages in 9.416s

Step 3: Prepare the url.

A simple hack to know the base url of MongoDB Service is to Open a Terminal and run Mongo Shell.

arjun@nodejs:~$ mongo
MongoDB shell version v3.4.9
connecting to: mongodb://127.0.0.1:27017
MongoDB server version: 3.4.9
Server has startup warnings: 
2017-10-29T18:15:36.110+0530 I STORAGE  [initandlisten]

While the Mongo Shell starts up, it echoes back the base url of MongoDB.

mongodb://127.0.0.1:27017

Step 4: With the help of mongodb package, create a MongoClient and connect to the url.

Example 1 – Connect to MongoDB via Node.js

Following is an Example Node.js program to make a Node.js MongoDB Connection.

node-js-mongodb-connection.js

// URL at which MongoDB service is running
var url = "mongodb://localhost:27017";

// A Client to MongoDB
var MongoClient = require('mongodb').MongoClient;

// Make a connection to MongoDB Service
MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  console.log("Connected to MongoDB!");
  db.close();
});

Output

arjun@java:~/workspace/nodejs/mongodb$ node node-js-mongodb-connection.js 
Connected to MongoDB!

Conclusion

In this Node.js MongoDB – Node.js Connect to MongoDB, we have learnt to find the url of the MongoDB Service and connect to the service from Node.js using MongoClient’s connect method, demonstrated by an Example program.

Node.js – Connect to MongoDB – Example