Create MongoDB Connection in Nodejs

In Node.js, To create a MongoDB connection in a Node.js application. we can use the MongoDB Node.js driver or Mongoose package.

Install MongoDB Node.js Driver:

First, install the MongoDB Node.js driver using npm if you haven't already:

Example:

npm install mongodb

Import MongoClient and Connect to MongoDB:

In the Node.js application, import the MongoClient class from the "MongoDB" package and use it to connect to your MongoDB server.

Example:

const { MongoClient } = require('mongodb');

// Connection URI
const uri = 'mongodb://localhost:27017'; // MongoDB default URI

// Create a new MongoClient
const client = new MongoClient(uri);

// Connect to the MongoDB server
client.connect((err) => {
  if (err) {
    console.error('Failed to connect to MongoDB:', err);
    return;
  }
  console.log('Connected successfully to MongoDB');

  // Perform database operations here

  // Close the connection when done
  client.close();
});

Note: with Latest Versions -> { useNewUrlParser: true, useUnifiedTopology: true } by default enabled.

Replace the Connection URI:

Replace 'mongodb://localhost:27017' with your MongoDB connection string.

Ensure that it includes the correct hostname, port, and any other necessary options.

Handle Connection Errors:

Handle any connection errors that may occur during the connection process.

Perform Database Operations:

Within the connect callback function, you can perform database operations such as inserting, updating, deleting, or querying documents.

Close the Connection:

Close the MongoDB connection when your application is done interacting with the database to avoid resource leaks.

Steps: with "mongoose" package

Install Mongoose:

Install the `Mongoose` package using npm.

Example:

npm install mongoose

Import Mongoose:

In your Node.js application, import the "mongoose" package using the "require()" method.

Example:

const mongoose = require('mongoose');

Connect to MongoDB:

Use the "mongoose.connect()" method to connect to your MongoDB database. we typically do this when our application starts up:

Example:

const uri = 'mongodb://localhost:27017/your_database_name'; // MongoDB connection string
mongoose.connect(uri)
  .then(() => {
    console.log('Connected to MongoDB');
    // Your code here
  })
  .catch((err) => {
    console.error('Error connecting to MongoDB:', err);
  });

Replace 'mongodb://localhost:27017/your_database_name' with your MongoDB connection string.

Note: with latest version: { useNewUrlParser: true, useUnifiedTopology: true } by default enabled.

Make sure, your "IP address is whitelisted" when you connect through MongoDB Atlas Database or you can make your database "accessible from anywhere".

Handle Connection Events:

We can listen to various events emitted by "Mongoose" to handle connection-related events.

Example:

mongoose.connection.on('connected', () => {
  console.log('Mongoose connected to MongoDB');
});

mongoose.connection.on('error', (err) => {
  console.error('Mongoose connection error:', err);
});

mongoose.connection.on('disconnected', () => {
  console.log('Mongoose disconnected from MongoDB');
});

Close the Connection:

We should close the "Mongoose connection" when application exits or shuts down.

This code listens for the SIGINT signal (Ctrl+C) and closes the Mongoose connection before exiting the application.

Example:

process.on('SIGINT', () => {
  mongoose.connection.close(() => {
    console.log('Mongoose connection closed due to app termination');
    process.exit(0);
  });
});

Define Models:

Once connected, we can define Mongoose models to interact with your MongoDB collections.

Models represent documents in a collection and provide an interface for querying and manipulating data.

Create Database -->

Create MongoDB Connection in Nodejs

In Node.js, To create a MongoDB connection in a Node.js application. we can use the MongoDB Node.js driver or Mongoose package.

Install MongoDB Node.js Driver:

First, install the MongoDB Node.js driver using npm if you haven't already:

Example:

npm install mongodb

Import MongoClient and Connect to MongoDB:

In the Node.js application, import the MongoClient class from the "MongoDB" package and use it to connect to your MongoDB server.

Example:

const { MongoClient } = require('mongodb');

// Connection URI
const uri = 'mongodb://localhost:27017'; // MongoDB default URI

// Create a new MongoClient
const client = new MongoClient(uri);

// Connect to the MongoDB server
client.connect((err) => {
  if (err) {
    console.error('Failed to connect to MongoDB:', err);
    return;
  }
  console.log('Connected successfully to MongoDB');

  // Perform database operations here

  // Close the connection when done
  client.close();
});

Note: with Latest Versions -> { useNewUrlParser: true, useUnifiedTopology: true } by default enabled.

Replace the Connection URI:

Replace 'mongodb://localhost:27017' with your MongoDB connection string.

Ensure that it includes the correct hostname, port, and any other necessary options.

Handle Connection Errors:

Handle any connection errors that may occur during the connection process.

Perform Database Operations:

Within the connect callback function, you can perform database operations such as inserting, updating, deleting, or querying documents.

Close the Connection:

Close the MongoDB connection when your application is done interacting with the database to avoid resource leaks.

Steps: with "mongoose" package

Install Mongoose:

Install the `Mongoose` package using npm.

Example:

npm install mongoose

Import Mongoose:

In your Node.js application, import the "mongoose" package using the "require()" method.

Example:

const mongoose = require('mongoose');

Connect to MongoDB:

Use the "mongoose.connect()" method to connect to your MongoDB database. we typically do this when our application starts up:

Example:

const uri = 'mongodb://localhost:27017/your_database_name'; // MongoDB connection string
mongoose.connect(uri)
  .then(() => {
    console.log('Connected to MongoDB');
    // Your code here
  })
  .catch((err) => {
    console.error('Error connecting to MongoDB:', err);
  });

Replace 'mongodb://localhost:27017/your_database_name' with your MongoDB connection string.

Note: with latest version: { useNewUrlParser: true, useUnifiedTopology: true } by default enabled.

Make sure, your "IP address is whitelisted" when you connect through MongoDB Atlas Database or you can make your database "accessible from anywhere".

Handle Connection Events:

We can listen to various events emitted by "Mongoose" to handle connection-related events.

Example:

mongoose.connection.on('connected', () => {
  console.log('Mongoose connected to MongoDB');
});

mongoose.connection.on('error', (err) => {
  console.error('Mongoose connection error:', err);
});

mongoose.connection.on('disconnected', () => {
  console.log('Mongoose disconnected from MongoDB');
});

Close the Connection:

We should close the "Mongoose connection" when application exits or shuts down.

This code listens for the SIGINT signal (Ctrl+C) and closes the Mongoose connection before exiting the application.

Example:

process.on('SIGINT', () => {
  mongoose.connection.close(() => {
    console.log('Mongoose connection closed due to app termination');
    process.exit(0);
  });
});

Define Models:

Once connected, we can define Mongoose models to interact with your MongoDB collections.

Models represent documents in a collection and provide an interface for querying and manipulating data.

Create Database -->