How to Create a RESTful API in NodeJS

RESTful APIs have become the standard for modern web applications, allowing for easy communication between client and server applications. In this blog, we will walk you through how to create a RESTful API in Node.js, a popular server-side language.

Step 1: Set up the project

First, create a new directory for your project and navigate to it in the command line. Then, run the following command to initialize a new Node.js project:

npm init

Follow the prompts to set up the project, and then install the following dependencies:

npm install express body-parser

We will be using the Express framework for our API and the body-parser module to parse incoming request bodies.

Step 2: Set up the server

Create a new file called server.js in your project directory and add the following code:

const express = require('express');
const bodyParser = require('body-parser');

const app = express();
const port = process.env.PORT || 3000;

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));

app.listen(port, () => {
  console.log(`Server running on port ${port}`);
});

In the code above, we import the necessary modules, create a new Express app, and set the port to either the environment variable or port 3000. We also configure the app to use the body-parser middleware to parse incoming requests.

Step 3: Define your API routes

Next, we will define the routes for our API. For this example, we will create a simple API that allows us to retrieve and create users.

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

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

// Get 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.send(user);
});

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

In the code above, we define three routes: /users, /users/:id, and /users. The first two routes allow us to retrieve users by ID or all users, while the last route allows us to create a new user.

Step 4: Test the API

We can now test our API using a tool like Postman. Send a GET request to /users to retrieve all users, or send a GET request to /users/:id to retrieve a specific user by ID. To create a new user, send a POST request to /users with a JSON payload containing the user’s name.

Congratulations, you have successfully created a RESTful API in Node.js! You can now build upon this example to create more complex APIs with additional routes and functionality.