How to Build a REST API with Express.js and MongoDB in 10 Minutes

Introduction

In this guide, we'll quickly build a simple REST API using Express.js and MongoDB. Whether you're new to backend development or need a refresher, this tutorial will help you start with a basic CRUD (Create, Read, Update, Delete) API.

What You'll Learn:

• Setting up an Express.js server

• Connecting to MongoDB

• Creating API routes

• Performing CRUD operations

• Testing the API using Postman

Prerequisites:

• Node.js installed

• Basic understanding of JavaScript

• MongoDB Atlas account (or local MongoDB setup)

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Step 1: Setting Up the Project

Open your terminal and create a new project:

mkdir express-mongo-api && cd express-mongo-api
npm init -y

Install required dependencies:

npm install express mongoose dotenv cors body-parser

• express – Web framework for Node.js

• mongoose – ODM for MongoDB

• dotenv – Manage environment variables

• cors – Handle cross-origin requests

• body-parser – Parse incoming JSON data

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Step 2: Connecting to MongoDB

Create a .env file in the root directory and add your MongoDB connection string:

MONGO_URI=your_mongodb_connection_string
PORT=5000

Now, create a file db.js to establish the database connection:

const mongoose = require('mongoose');
require('dotenv').config();

mongoose.connect(process.env.MONGO_URI, { useNewUrlParser: true, useUnifiedTopology: true })
  .then(() => console.log('MongoDB Connected'))
  .catch(err => console.error(err));

module.exports = mongoose;

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Step 3: Defining the User Model

Inside a models folder, create User.js:

const mongoose = require('mongoose');

const userSchema = new mongoose.Schema({
  name: String,
  email: String,
  age: Number
});

module.exports = mongoose.model('User', userSchema);

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Step 4: Building API Routes

Create a routes folder and add userRoutes.js:

const express = require('express');
const router = express.Router();
const User = require('../models/User');

// Create a user
router.post('/', async (req, res) => {
  try {
    const user = new User(req.body);
    await user.save();
    res.status(201).json(user);
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

// Get all users
router.get('/', async (req, res) => {
  const users = await User.find();
  res.json(users);
});

// Get a user by ID
router.get('/:id', async (req, res) => {
  const user = await User.findById(req.params.id);
  res.json(user);
});

// Update a user
router.put('/:id', async (req, res) => {
  const user = await User.findByIdAndUpdate(req.params.id, req.body, { new: true });
  res.json(user);
});

// Delete a user
router.delete('/:id', async (req, res) => {
  await User.findByIdAndDelete(req.params.id);
  res.json({ message: 'User deleted' });
});

module.exports = router;

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Step 5: Setting Up the Express Server

Create server.js in the root directory:

const express = require('express');
require('dotenv').config();
require('./db'); // Connect to MongoDB

const app = express();
app.use(express.json()); // Middleware to parse JSON
app.use('/users', require('./routes/userRoutes')); // Use user routes

const PORT = process.env.PORT || 5000;
app.listen(PORT, () => console.log(`Server running on port ${PORT}`));

Run the server:

node server.js

You should see "MongoDB Connected" and "Server running on port 5000" in your terminal.

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Step 6: Testing the API with Postman

Use Postman or cURL to test the API:

Create a user (POST /users)

{
  "name": "John Doe",
  "email": "johndoe@example.com",
  "age": 25
}

Get all users (GET /users)

Returns an array of users.

Get a user by ID (GET /users/:id)

Fetches a specific user by their ID.

Update a user (PUT /users/:id)

Send an updated JSON object.

Delete a user (DELETE /users/:id)

Removes a user from the database.

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Optional: Deploying the API

• Deploy to Render, Vercel, or Railway for free hosting.

• Use MongoDB Atlas instead of local MongoDB.

• Add authentication using JWT (JSON Web Tokens).

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