Express REST API - Learning Project

A complete REST API built with Express.js and MongoDB to learn CRUD operations.

🎯 Learning Objectives

• Understand REST API principles
• Learn HTTP methods: GET, POST, PUT, PATCH, DELETE
• Work with Express.js and MVC pattern
• Connect to MongoDB
• Interact with the API using Fetch, curl, or the VS Code REST Client

✨ Features

• RESTful API with Express.js
• MongoDB integration with Mongoose
• CORS enabled for cross-origin requests
• MVC architecture pattern
• Clean, simplified response format
• Top-level await support (ES modules)

📁 Project Structure

📁 let's start mongoAPI/
├── 📁 config/
│   └── database.js          # MongoDB connection
├── 📁 controllers/
│   └── postController.js    # Business logic
├── 📁 models/
│   └── Post.js              # Database schema
├── 📁 routes/
│   └── postRoutes.js        # Route definitions (chained)
├── server.js                # Main app (CORS enabled)
├── test-api.http            # REST Client test file
├── .env                     # Environment variables
└── package.json

📦 Installation

1. Install dependencies:

npm install

2. Make sure MongoDB is running on your local machine

3. Update .env file with your MongoDB connection string:

MONGODB_URI=mongodb://localhost:27017
DB_NAME=my_blog
PORT=3000

4. Start the server:

npm start

Or use watch mode for development:

npm run dev

Requirements:
- Node.js 18+ (for native `--watch` and top‑level await)
- MongoDB running locally or a connection URI

## 🔧 Dependencies

- **express** - Web framework
- **mongoose** - MongoDB ODM
- **cors** - Enable Cross-Origin Resource Sharing
- **dotenv** - Environment variable management

🛠️ API Endpoints

Method	Endpoint	Description
GET	/api/posts	Get all posts
GET	/api/posts/:id	Get a single post by ID
POST	/api/posts	Create a new post
PUT	/api/posts/:id	Update a post (full update)
PATCH	/api/posts/:id	Update a post (partial update)
DELETE	/api/posts/:id	Delete a post

Response shape

• Success responses return the raw document (or array) directly.
• Errors are returned as { "error": "message" } with proper status codes (400, 404, 500).
• DELETE returns 204 No Content (no body).

📝 Post Object Structure

{
  "_id": "507f1f77bcf86cd799439011",
  "title": "My Post Title"
}

🧪 Testing with Fetch API

GET all posts

const response = await fetch("http://localhost:3000/api/posts");
const data = await response.json();
console.log(data);

GET single post

const response = await fetch("http://localhost:3000/api/posts/POST_ID");
const data = await response.json();
console.log(data);

POST - Create a new post

const response = await fetch("http://localhost:3000/api/posts", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    title: "My New Post",
  }),
});
const data = await response.json();
console.log(data);

PUT - Update a post (full)

const response = await fetch("http://localhost:3000/api/posts/POST_ID", {
  method: "PUT",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    title: "Updated Title",
  }),
});
const data = await response.json();
console.log(data);

PATCH - Update a post (partial)

const response = await fetch("http://localhost:3000/api/posts/POST_ID", {
  method: "PATCH",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    title: "Partially Updated Title",
  }),
});
const data = await response.json();
console.log(data);

DELETE - Delete a post

const response = await fetch("http://localhost:3000/api/posts/POST_ID", {
  method: "DELETE",
});
console.log(response.status); // 204
console.log(response.ok); // true

🧪 Testing with curl (optional)

GET all posts:

curl http://localhost:3000/api/posts

Create a post:

curl -X POST http://localhost:3000/api/posts \
  -H "Content-Type: application/json" \
  -d '{"title":"My First Blog Post"}'

Get one:

curl http://localhost:3000/api/posts/POST_ID

Update (PUT):

curl -X PUT http://localhost:3000/api/posts/POST_ID \
  -H "Content-Type: application/json" \
  -d '{"title":"Updated Title"}'

Patch:

curl -X PATCH http://localhost:3000/api/posts/POST_ID \
  -H "Content-Type: application/json" \
  -d '{"title":"Partially Updated Title"}'

Delete (204 No Content):

curl -i -X DELETE http://localhost:3000/api/posts/POST_ID

🔍 Understanding REST & HTTP Methods

• GET: Retrieve data (Read)
• POST: Create new data (Create)
• PUT: Update entire resource (Update - full)
• PATCH: Update part of resource (Update - partial)
• DELETE: Remove data (Delete)

💡 Tips

1. CORS is enabled - API can be accessed from any origin (browser apps, frontends, etc.)
2. Use the browser console or a separate HTML file to test fetch requests
3. Use the test-api.http file for quick testing with the VS Code REST Client extension
4. Always check the server console for logs
5. MongoDB must be running before starting the server
6. Routes use chaining for cleaner code organization

📚 Next Steps

1. Add more fields to the Post model
2. Add authentication
3. Add pagination for GET requests
4. Add search and filtering
5. Add validation middleware
6. Create a frontend to interact with the API