# 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:

```bash
npm install express mongoose dotenv
```

### 5\. Creating the Server

1. Make a file called `server.js`
    

Basic setup:

```javascript
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:
    

```plaintext
MONGO_URI=your_connection_string_here
```

* In `server.js`, add:
    

```javascript
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`:

```javascript
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`:
    

```javascript
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:

```javascript
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`](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
    

<div data-node-type="callout">
<div data-node-type="callout-emoji">💡</div>
<div data-node-type="callout-text">Follow me on 𝕏 @qzseeker</div>
</div>