In this tutorial, we'll learn how to connect a Node.js application with MongoDB. Node.js is a powerful JavaScript runtime built on Chrome's V8 JavaScript engine and MongoDB is a document-oriented NoSQL database, both are widely used in modern web application development.
You will learn:
Prerequisites:
We will be using mongoose, a MongoDB object modeling tool designed to work in an asynchronous environment. It provides a straight-forward, schema-based solution to model your application data.
Steps:
Install mongoose: You can install mongoose by running npm install mongoose in your terminal.
Import mongoose: In your main server file, import mongoose using const mongoose = require('mongoose');.
Connect to MongoDB: Use mongoose.connect() to connect to your MongoDB database.
Example 1: Connecting to MongoDB
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test', {useNewUrlParser: true, useUnifiedTopology: true});
const db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function() {
console.log("We're connected!");
});
In this snippet, we first import mongoose and then we connect to MongoDB running on localhost with the database name test. The mongoose.connect() function takes two arguments: a connection string and an options object.
The db.on('error') event will be triggered if there is a connection error. The db.once('open') event will be triggered once when the connection is open.
In this tutorial, you've learned how to connect Node.js with MongoDB using mongoose. You've also learned how to handle connection events.
Next Steps:
mongooseAdditional resources:
Exercise 1: Connect to a MongoDB database named 'practice'.
Exercise 2: Handle a connection error by printing a custom error message.
Exercise 3: Print a custom success message once the connection is open.
Solutions:
Solution 1:
mongoose.connect('mongodb://localhost/practice', {useNewUrlParser: true, useUnifiedTopology: true});
Solution 2:
db.on('error', function() {
console.error('There was a connection error!');
});
Solution 3:
db.once('open', function() {
console.log("Successfully connected to the database!");
});
Tips for further practice: