🗄️ CRUD User API

A clean, standards-compliant RESTful CRUD API for user management. Built with Express 5 and SQLite, following MVC architecture (Route → Controller → Service → Model) with input validation, centralized error handling, and interactive Swagger documentation.

Features

• Full CRUD Operations: Create, Read, Update, and Delete users through RESTful endpoints
• MVC Architecture: Clean separation of concerns with Route → Controller → Service → Model layers
• Input Validation: Request body validation using express-validator with detailed error messages
• Centralized Error Handling: Consistent error responses with proper HTTP status codes
• Duplicate Detection: Email uniqueness enforcement with 409 Conflict response
• Swagger Documentation: Interactive API docs with OpenAPI 3.0 spec at /api-docs
• SQLite Database: Lightweight, zero-configuration database with WAL mode for performance
• Consistent Response Format: Standardized JSON responses with success flag across all endpoints

Live Demo

🔗 View Live API

📄 Swagger Docs

Technologies

• Node.js: JavaScript runtime (>= 18.0.0)
• Express 5: Web framework for building RESTful APIs
• SQLite (better-sqlite3): Lightweight embedded SQL database with synchronous API
• express-validator: Middleware for request body validation
• Swagger (swagger-jsdoc + swagger-ui-express): Interactive API documentation
• dotenv: Environment variable management
• nodemon: Development auto-reload

Project Structure

├── src/
│   ├── config/
│   │   ├── database.js          # SQLite connection & table setup
│   │   └── swagger.js           # OpenAPI 3.0 specification
│   ├── models/
│   │   └── userModel.js         # Data access layer (SQL queries)
│   ├── services/
│   │   └── userService.js       # Business logic & error throwing
│   ├── controllers/
│   │   └── userController.js    # Request/response handling
│   ├── routes/
│   │   └── userRoutes.js        # Route definitions with JSDoc
│   ├── middlewares/
│   │   ├── validate.js          # Input validation rules
│   │   └── errorHandler.js      # Centralized error handler
│   └── app.js                   # Express app configuration
├── server.js                    # Entry point
├── .env                         # Environment variables
└── package.json

Installation

Prerequisites

• Node.js >= 18.0.0
• npm (comes with Node.js)

Local Development

# Clone the repository
git clone https://github.com/Serkanbyx/s3.2_Crude-User-API.git

# Navigate to project directory
cd s3.2_Crude-User-API

# Install dependencies
npm install

# Start in development mode (with auto-reload)
npm run dev

# Or start in production mode
npm start

The server will run at http://localhost:3000 and Swagger docs at http://localhost:3000/api-docs.

Usage

1. Start the server with npm run dev
2. Open http://localhost:3000/api-docs in your browser for interactive documentation
3. Use Swagger UI's "Try it out" button to test endpoints directly
4. Or use any HTTP client (Postman, curl, etc.) to send requests

API Endpoints

Method	Endpoint	Description	Status Codes
GET	/users	Get all users	200
GET	/users/:id	Get user by ID	200, 404
POST	/users	Create a new user	201, 400, 409
PUT	/users/:id	Update a user	200, 400, 404, 409
DELETE	/users/:id	Delete a user	204, 404

How It Works?

Request Body (POST & PUT)

{
  "name": "John Doe",
  "email": "john@example.com",
  "age": 25
}

Field	Type	Required	Rules
name	string	Yes	2-50 characters
email	string	Yes	Valid email format, unique
age	integer	No	Between 1 and 150

Response Format

Success (single resource):

{
  "success": true,
  "data": {
    "id": 1,
    "name": "John Doe",
    "email": "john@example.com",
    "age": 25,
    "created_at": "2026-02-21 12:00:00",
    "updated_at": "2026-02-21 12:00:00"
  }
}

Success (list):

{
  "success": true,
  "count": 2,
  "data": [...]
}

Validation Error (400):

{
  "success": false,
  "message": "Validation failed",
  "errors": [
    { "field": "email", "message": "Please provide a valid email address" }
  ]
}

Not Found (404):

{
  "success": false,
  "message": "User not found"
}

Conflict (409):

{
  "success": false,
  "message": "A user with this email already exists"
}

Architecture Flow

Client Request
     │
     ▼
  Routes        → Defines endpoints & attaches validation
     │
     ▼
  Middleware     → Validates input (express-validator)
     │
     ▼
  Controller    → Handles req/res, delegates to service
     │
     ▼
  Service       → Business logic, throws AppError on failure
     │
     ▼
  Model         → SQL queries via better-sqlite3
     │
     ▼
  Database      → SQLite (database.db)

Features in Detail

✅ Full CRUD operations (Create, Read, Update, Delete)

✅ Input validation with detailed field-level error messages

✅ Centralized error handling middleware

✅ Duplicate email detection (409 Conflict)

✅ Interactive Swagger UI documentation

✅ SQLite with WAL mode for better read performance

✅ Consistent JSON response format

✅ Render deployment ready (0.0.0.0 binding)

Contributing

Contributions are welcome! Please read the Contributing Guide for details on the process.

1. Fork the repository
2. Create your feature branch: git checkout -b feature/amazing-feature
3. Commit your changes: git commit -m "feat: add amazing feature"
4. Push to the branch: git push origin feature/amazing-feature
5. Open a Pull Request

License

This project is licensed under the MIT License. See the LICENSE file for details.

Developer

Serkanby

• Website: serkanbayraktar.com
• GitHub: @Serkanbyx
• Email: serkanbyx1@gmail.com

Contact

• Have a bug or feature request? Open an issue
• Email: serkanbyx1@gmail.com
• Website: serkanbayraktar.com

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