Introduction

If you're new to building applications with Node.js and MongoDB, you may be eager to get started with Mongoose—an elegant MongoDB object modeling tool designed to work in an asynchronous environment. With Mongoose, you can define schemas, models, and easily perform CRUD (Create, Read, Update, Delete) operations with your MongoDB database. This guide will take you through the steps to connect to MongoDB using Mongoose, providing clear examples and explanations along the way.

Prerequisites

Before we dive into our Mongoose connection setup, ensure you have the following:

• Node.js installed (preferably version 12.x or higher).
• MongoDB installed locally or access to a MongoDB Atlas cluster.
• Basic knowledge of JavaScript and Node.js.

Step 1: Setting Up Your Project

First things first, let's create a new directory for our Node.js application:

mkdir mongoose-crud-app
cd mongoose-crud-app

Next, initialize a new npm project:

npm init -y

This command creates a package.json file in your project directory, setting up your project for dependency management.

Step 2: Installing Dependencies

We need to install Mongoose as our primary dependency:

npm install mongoose

If you're using TypeScript in your project, you should also install the type definitions for Mongoose:

npm install @types/mongoose --save-dev

Step 3: Connecting to MongoDB

Now it’s time to connect our Node.js application to a MongoDB database using Mongoose. Create a new file named app.js (or app.ts if you're using TypeScript):

const mongoose = require('mongoose');

// Replace '<URI>' with your MongoDB connection string
const uri = '<URI>';

mongoose.connect(uri, { useNewUrlParser: true, useUnifiedTopology: true })
  .then(() => {
      console.log('Successfully connected to MongoDB');
  })
  .catch(err => {
      console.error('Connection error', err);
  });

Explanation

• mongoose.connect(uri): This function attempts to connect to the MongoDB database specified in your connection URI.
• useNewUrlParser and useUnifiedTopology: These options are recommended to avoid deprecation warnings.

You should replace '<URI>' with your actual connection string. For a local MongoDB instance, it looks like this:

mongodb://localhost:27017/mydatabase

If you're using MongoDB Atlas, you can find your connection string in the Atlas dashboard after setting up your cluster.

Step 4: Defining a Schema

With a successful connection, let’s define a simple schema. Below the connection code, add the following:

const Schema = mongoose.Schema;

const UserSchema = new Schema({
    name: { type: String, required: true },
    email: { type: String, required: true, unique: true },
    password: { type: String, required: true }
});

const User = mongoose.model('User', UserSchema);

Explanation

• Schema: This defines the structure of the documents in a collection, specifying the fields and their data types.
• User model: This creates a model for interacting with the "users" collection in the database.

Step 5: Performing CRUD Operations

Now that we have our connection and schema set up, let’s perform some basic CRUD operations. Below the schema definition, add the following code snippets:

Create a User

const createUser = async () => {
    const user = new User({
        name: 'John Doe',
        email: 'john.doe@example.com',
        password: 'securePassword123'
    });
    
    try {
        const savedUser = await user.save();
        console.log('User Created:', savedUser);
    } catch (error) {
        console.error('Error creating user', error);
    }
};

createUser();

Read Users

const readUsers = async () => {
    try {
        const users = await User.find();
        console.log('Users:', users);
    } catch (error) {
        console.error('Error reading users', error);
    }
};

readUsers();

Update a User

const updateUser = async (userId) => {
    try {
        const updatedUser = await User.findByIdAndUpdate(userId, { name: 'Jane Doe' }, { new: true });
        console.log('Updated User:', updatedUser);
    } catch (error) {
        console.error('Error updating user', error);
    }
};

// Call updateUser with an existing user ID
updateUser('5f50c31b6b58f105b8e29727');

Delete a User

const deleteUser = async (userId) => {
    try {
        await User.findByIdAndDelete(userId);
        console.log('User deleted');
    } catch (error) {
        console.error('Error deleting user', error);
    }
};

// Call deleteUser with an existing user ID
deleteUser('5f50c31b6b58f105b8e29727');

Conclusion

In this blog, we've set up a Node.js application, connected to a MongoDB database using Mongoose, and performed basic CRUD operations. As you advance your development skills, Mongoose will continue to be a valuable tool that provides an easy-to-use interface for interacting with MongoDB. Happy coding!