Building a REST API with Node.js and Express

Creating a RESTful API is a common task for web developers. In this tutorial, we'll build a simple REST API using Node.js and Express.

Setting Up the Project

First, create a new directory for your project and initialize it:

mkdir my-rest-api
cd my-rest-api
npm init -y

Install the necessary packages:

npm install express mongoose cors dotenv

Creating the Server

Create an index.js file to set up your Express server:

const express = require('express');
const cors = require('cors');
require('dotenv').config();

const app = express();
const PORT = process.env.PORT || 5000;

// Middleware
app.use(cors());
app.use(express.json());

// Basic route
app.get('/', (req, res) => {
  res.json({ message: 'Welcome to the REST API' });
});

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

Connecting to MongoDB

Let's add MongoDB connection with Mongoose:

const mongoose = require('mongoose');

mongoose.connect(process.env.MONGODB_URI)
  .then(() => console.log('Connected to MongoDB'))
  .catch(err => console.error('Could not connect to MongoDB', err));

Creating a Model

Create a models directory and add a file for your model, for example product.model.js:

const mongoose = require('mongoose');

const productSchema = new mongoose.Schema({
  name: {
    type: String,
    required: true,
    trim: true
  },
  description: {
    type: String,
    required: true
  },
  price: {
    type: Number,
    required: true,
    min: 0
  },
  category: {
    type: String,
    required: true
  },
  createdAt: {
    type: Date,
    default: Date.now
  }
});

module.exports = mongoose.model('Product', productSchema);

Creating Routes

Create a routes directory and add a file for your routes, for example product.routes.js:

const express = require('express');
const router = express.Router();
const Product = require('../models/product.model');

// Get all products
router.get('/', async (req, res) => {
  try {
    const products = await Product.find();
    res.json(products);
  } catch (err) {
    res.status(500).json({ message: err.message });
  }
});

// Get one product
router.get('/:id', getProduct, (req, res) => {
  res.json(res.product);
});

// Create a product
router.post('/', async (req, res) => {
  const product = new Product({
    name: req.body.name,
    description: req.body.description,
    price: req.body.price,
    category: req.body.category
  });

  try {
    const newProduct = await product.save();
    res.status(201).json(newProduct);
  } catch (err) {
    res.status(400).json({ message: err.message });
  }
});

// Update a product
router.patch('/:id', getProduct, async (req, res) => {
  if (req.body.name != null) {
    res.product.name = req.body.name;
  }
  if (req.body.description != null) {
    res.product.description = req.body.description;
  }
  if (req.body.price != null) {
    res.product.price = req.body.price;
  }
  if (req.body.category != null) {
    res.product.category = req.body.category;
  }

  try {
    const updatedProduct = await res.product.save();
    res.json(updatedProduct);
  } catch (err) {
    res.status(400).json({ message: err.message });
  }
});

// Delete a product
router.delete('/:id', getProduct, async (req, res) => {
  try {
    await res.product.remove();
    res.json({ message: 'Product deleted' });
  } catch (err) {
    res.status(500).json({ message: err.message });
  }
});

// Middleware to get product by ID
async function getProduct(req, res, next) {
  let product;
  try {
    product = await Product.findById(req.params.id);
    if (product == null) {
      return res.status(404).json({ message: 'Cannot find product' });
    }
  } catch (err) {
    return res.status(500).json({ message: err.message });
  }

  res.product = product;
  next();
}

module.exports = router;

Connecting Routes to the Server

Update your index.js to use the routes:

// Import routes
const productRoutes = require('./routes/product.routes');

// Use routes
app.use('/api/products', productRoutes);

Testing the API

You can test your API using tools like Postman or by writing simple HTTP requests using a library like axios or fetch.

Conclusion

Congratulations! You've built a basic REST API with Node.js and Express. You can extend this API by adding authentication, validation, and more complex endpoints to suit your application's needs.