Making APIs with MERN Stack

1. Basics of APIs

• API = Application Programming Interface

• Allows different software to talk to each other

• We'll focus on web APIs that use HTTP

2. RESTful API Design

• REST = Representational State Transfer

• Design style for APIs

• Uses standard HTTP methods:

  • GET: Fetch data

  • POST: Create new data

  • PUT/PATCH: Update existing data

  • DELETE: Remove data

3. MERN Stack Overview

• M: MongoDB (database)

• E: Express.js (backend framework)

• R: React (frontend, not used for API itself)

• N: Node.js (JavaScript runtime)

4. Setting Up the Project

1. Create a new folder for your project

2. Run npm init to start a new Node.js project

Install needed packages:

npm install express mongoose dotenv

5. Creating the Server

1. Make a file called server.js

Basic setup:

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

app.use(express.json());

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

6. Connecting to MongoDB

1. Create a MongoDB Atlas account (free tier available)

2. Get your connection string

3. Create a .env file and add your connection string:

MONGO_URI=your_connection_string_here

• In server.js, add:

const mongoose = require('mongoose');
require('dotenv').config();

mongoose.connect(process.env.MONGO_URI)
  .then(() => console.log('Connected to MongoDB'))
  .catch(err => console.error('MongoDB connection error:', err));

7. Creating a Model

1. Make a new folder called models

Create a file, e.g., Item.js:

const mongoose = require('mongoose');

const ItemSchema = new mongoose.Schema({
  name: { type: String, required: true },
  description: String,
  price: { type: Number, required: true }
});

module.exports = mongoose.model('Item', ItemSchema);

8. Making API Routes

1. Create a folder called routes

2. Make a file, e.g., items.js:

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

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

// POST a new item
router.post('/', async (req, res) => {
  const item = new Item({
    name: req.body.name,
    description: req.body.description,
    price: req.body.price
  });

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

// Add more routes (GET by ID, PUT, DELETE) here

module.exports = router;

In server.js add:

const itemsRouter = require('./routes/items');
app.use('/api/items', itemsRouter);

9. Testing Your API

• Use Postman or any API testing tool

• Send requests to http://localhost:5000/api/items

10. Next Steps

• Add authentication (e.g., using JSON Web Tokens)

• Create more models and routes

• Add input validation

• Learn about error handling and best practices