# 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)
    

---

## Step 1: Setting Up the Project

Open your terminal and create a new project:

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

Install required dependencies:

```sh
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
    

---

## Step 2: Connecting to MongoDB

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

```plaintext
MONGO_URI=your_mongodb_connection_string
PORT=5000
```

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

```javascript
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;
```

---

## Step 3: Defining the User Model

Inside a `models` folder, create `User.js`:

```javascript
const mongoose = require('mongoose');

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

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

---

## Step 4: Building API Routes

Create a `routes` folder and add `userRoutes.js`:

```javascript
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;
```

---

## Step 5: Setting Up the Express Server

Create `server.js` in the root directory:

```javascript
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:

```sh
node server.js
```

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

---

## Step 6: Testing the API with Postman

Use **Postman** or **cURL** to test the API:

### Create a user (POST `/users`)

```json
{
  "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.

---

## 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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