DevAPIHub

In this tutorial, we'll walk through creating a RESTful API using Node.js and Express. We'll build a simple books API that demonstrates core concepts like routing, middleware, error handling, and basic CRUD operations.

Prerequisites

Node.js installed on your machine
Basic understanding of JavaScript
A code editor
Postman or similar tool for testing APIs

Project Setup

First, create a new directory and initialize your project:

mkdir books-api
cd books-api
npm init -y

Install the necessary dependencies:

npm install express body-parser dotenv

Project Structure

Create the following file structure:

books-api/
├── src/
│   ├── routes/
│   │   └── books.js
│   ├── middleware/
│   │   └── errorHandler.js
│   └── server.js
├── package.json
└── .env

Basic Server Setup

Create src/server.js:

const express = require('express');
const bodyParser = require('body-parser');
const booksRouter = require('./routes/books');
const errorHandler = require('./middleware/errorHandler');

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

// Middleware
app.use(bodyParser.json());

// Routes
app.use('/api/books', booksRouter);

// Error handling middleware
app.use(errorHandler);

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

Creating Routes

Create src/routes/books.js:

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

// In-memory database
let books = [
    { id: 1, title: 'The Great Gatsby', author: 'F. Scott Fitzgerald' },
    { id: 2, title: '1984', author: 'George Orwell' }
];

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

// GET book by ID
router.get('/:id', (req, res) => {
    const book = books.find(b => b.id === parseInt(req.params.id));
    if (!book) return res.status(404).json({ message: 'Book not found' });
    res.json(book);
});

// POST new book
router.post('/', (req, res) => {
    const book = {
        id: books.length + 1,
        title: req.body.title,
        author: req.body.author
    };
    books.push(book);
    res.status(201).json(book);
});

// PUT update book
router.put('/:id', (req, res) => {
    const book = books.find(b => b.id === parseInt(req.params.id));
    if (!book) return res.status(404).json({ message: 'Book not found' });

    book.title = req.body.title || book.title;
    book.author = req.body.author || book.author;
    
    res.json(book);
});

// DELETE book
router.delete('/:id', (req, res) => {
    const bookIndex = books.findIndex(b => b.id === parseInt(req.params.id));
    if (bookIndex === -1) return res.status(404).json({ message: 'Book not found' });

    books.splice(bookIndex, 1);
    res.status(204).send();
});

module.exports = router;

Error Handling

Create src/middleware/errorHandler.js:

function errorHandler(err, req, res, next) {
    console.error(err.stack);
    
    res.status(500).json({
        message: 'Something went wrong!',
        error: process.env.NODE_ENV === 'development' ? err.message : undefined
    });
}

module.exports = errorHandler;

Input Validation

Let's add basic validation middleware for our POST requests:

const validateBook = (req, res, next) => {
    if (!req.body.title || !req.body.author) {
        return res.status(400).json({
            message: 'Title and author are required'
        });
    }
    next();
};

// Apply to POST route
router.post('/', validateBook, (req, res) => {
    // ... existing post logic
});

Testing the API

Start your server:

node src/server.js

Use these curl commands to test your API:

# Get all books
curl http://localhost:3000/api/books

# Get single book
curl http://localhost:3000/api/books/1

# Create new book
curl -X POST -H "Content-Type: application/json" \
    -d '{"title":"New Book","author":"John Doe"}' \
    http://localhost:3000/api/books

# Update book
curl -X PUT -H "Content-Type: application/json" \
    -d '{"title":"Updated Title"}' \
    http://localhost:3000/api/books/1

# Delete book
curl -X DELETE http://localhost:3000/api/books/1

Next Steps

To enhance this basic API, consider:

Conclusion

You now have a working RESTful API built with Node.js and Express! This basic implementation demonstrates core concepts like routing, middleware, and error handling. While this example uses an in-memory array for storage, you can extend it by adding a database and implementing additional features as needed.

Remember to always:

Validate input data
Handle errors appropriately
Follow REST conventions
Implement proper security measures
Document your API endpoints

Happy coding! 🚀