How to make your first Rest API with Nodejs and MongoDb

Creating an API locally using Node.js is a great way to get started with backend development. Node.js is a powerful runtime environment that allows you to execute JavaScript code on the server side. In this blog, we'll walk through the steps to create a simple API using Node.js, Express.js (a popular web framework for Node.js), and MongoDB (a NoSQL database).

Prerequisites

Before we begin, make sure you have the following installed on your machine:

• Node.js: You can download it from the official website.

• npm (Node Package Manager): It comes bundled with Node.js.

Step 1: Set Up Your Project

1. Create a new directory for your project

mkdir my-first-api
cd my-first-api

2. Initialize a new Node.js project

npm init -y

2. Install Express.js

npm install express

Step 2: Create the Basic Server

1. Create a file named index.js in your project directory.

2. Set up a basic Express server in index.js

const express = require('express');
const app = express();
const port = 3000;

app.use(express.json());

app.get('/', (req, res) => {
  res.send('Hello World!');
});

app.listen(port, () => {
  console.log(`Server is running on http://localhost:${port}`);
});

3. Run your server

node index.js

You should see the message Server is running on http://localhost:3000 in your terminal. Open your browser and navigate to http://localhost:3000 to see the "Hello World!" message

Step 3: Create Your First Route

Let's create a simple route to handle CRUD (Create, Read, Update, Delete) operations for a resource, such as "users".

1. Add the following code to index.js

let users = [
  { id: 1, name: 'John Doe' },
  { id: 2, name: 'Jane Smith' }
];

// Get all users
app.get('/users', (req, res) => {
  res.json(users);
});

// Get a single user by ID
app.get('/users/:id', (req, res) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  if (!user) return res.status(404).send('User not found.');
  res.json(user);
});

// Create a new user
app.post('/users', (req, res) => {
  const newUser = {
    id: users.length + 1,
    name: req.body.name
  };
  users.push(newUser);
  res.status(201).json(newUser);
});

// Update a user
app.put('/users/:id', (req, res) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  if (!user) return res.status(404).send('User not found.');

  user.name = req.body.name;
  res.json(user);
});

// Delete a user
app.delete('/users/:id', (req, res) => {
  const userIndex = users.findIndex(u => u.id === parseInt(req.params.id));
  if (userIndex === -1) return res.status(404).send('User not found.');

  users.splice(userIndex, 1);
  res.status(204).send();
});

2. Test your API using tools like Postman or curl.

Step 4: Organize Your Code

As your API grows, it's a good practice to organize your code into separate modules.

1. Create a directory named routes and a file named users.js inside it.

2. Move the user-related routes to routes/users.js

const express = require('express');
const router = express.Router();

let users = [
  { id: 1, name: 'John Doe' },
  { id: 2, name: 'Jane Smith' }
];

// Get all users
router.get('/', (req, res) => {
  res.json(users);
});

// Get a single user by ID
router.get('/:id', (req, res) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  if (!user) return res.status(404).send('User not found.');
  res.json(user);
});

// Create a new user
router.post('/', (req, res) => {
  const newUser = {
    id: users.length + 1,
    name: req.body.name
  };
  users.push(newUser);
  res.status(201).json(newUser);
});

// Update a user
router.put('/:id', (req, res) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  if (!user) return res.status(404).send('User not found.');

  user.name = req.body.name;
  res.json(user);
});

// Delete a user
router.delete('/:id', (req, res) => {
  const userIndex = users.findIndex(u => u.id === parseInt(req.params.id));
  if (userIndex === -1) return res.status(404).send('User not found.');

  users.splice(userIndex, 1);
  res.status(204).send();
});

module.exports = router;

3. Update index.js to use the new route module

const express = require('express');
const app = express();
const port = 3000;
const userRoutes = require('./routes/users');

app.use(express.json());
app.use('/users', userRoutes);

app.listen(port, () => {
  console.log(`Server is running on http://localhost:${port}`);
});

Step 5: Connect to a Database

For a real-world application, you'll want to store your data in a database. You can use databases like MongoDB, MySQL, or PostgreSQL. For simplicity, let's use MongoDB with Mongoose, an ODM (Object Data Modeling) library for MongoDB and Node.js.

1. Install Mongoose

npm install mongoose

2. Create a file named models/user.js to define the User schema

const mongoose = require('mongoose');

const userSchema = new mongoose.Schema({
  name: { type: String, required: true }
});

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

module.exports = User;

3. Update routes/users.js to use Mongoose

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

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

// Get a single user by ID
router.get('/:id', async (req, res) => {
  const user = await User.findById(req.params.id);
  if (!user) return res.status(404).send('User not found.');
  res.json(user);
});

// Create a new user
router.post('/', async (req, res) => {
  const newUser = new User({ name: req.body.name });
  await newUser.save();
  res.status(201).json(newUser);
});

// Update a user
router.put('/:id', async (req, res) => {
  const user = await User.findByIdAndUpdate(req.params.id, { name: req.body.name }, { new: true });
  if (!user) return res.status(404).send('User not found.');
  res.json(user);
});

// Delete a user
router.delete('/:id', async (req, res) => {
  const user = await User.findByIdAndDelete(req.params.id);
  if (!user) return res.status(404).send('User not found.');
  res.status(204).send();
});

module.exports = router;

4. Update index.js to connect to MongoDB

const express = require('express');
const mongoose = require('mongoose');
const app = express();
const port = 3000;
const userRoutes = require('./routes/users');

app.use(express.json());
app.use('/users', userRoutes);

mongoose.connect('mongodb://localhost:27017/mydatabase', { useNewUrlParser: true, useUnifiedTopology: true })
  .then(() => console.log('MongoDB connected'))
  .catch(err => console.log(err));

app.listen(port, () => {
  console.log(`Server is running on http://localhost:${port}`);
});

Conclusion

Congratulations! You've created your first REST API in Node.js using Express.js and connected it to a MongoDB database. This is a foundational step in building scalable and efficient web services. From here, you can expand your API by adding more routes, implementing authentication, and optimizing performance.