Flask REST API - User Management

A simple REST API built with Flask for managing user data. This project demonstrates fundamental API development concepts including CRUD operations, HTTP methods, status codes, and JSON handling.

Features

• Complete CRUD Operations: Create, Read, Update, Delete users
• RESTful Design: Follows REST API conventions
• JSON Support: All data exchange in JSON format
• Error Handling: Proper HTTP status codes and error messages
• Data Validation: Input validation and duplicate prevention
• In-Memory Storage: Simple dictionary-based data storage

API Endpoints

Method	Endpoint	Description
GET	/users	Get all users
GET	/users/<id>	Get user by ID
POST	/users	Create new user
PUT	/users/<id>	Update user
DELETE	/users/<id>	Delete user
GET	/health	Health check

Installation & Setup

Prerequisites

• Python 3.7 or higher
• Flask

Steps

1. Clone the repository

   git clone https://github.com/yourusername/flask-rest-api.git
   cd flask-rest-api

2. Install Flask

   pip install flask

3. Run the application

   python app.py

4. Access the API

   • Base URL: http://localhost:5000
   • Health check: http://localhost:5000/health

Usage Examples

1. Get All Users

curl -X GET http://localhost:5000/users

Response:

{
  "status": "success",
  "data": [
    {
      "id": 1,
      "name": "John Doe",
      "email": "john@example.com",
      "created_at": "2024-01-15"
    }
  ],
  "count": 1
}

2. Get User by ID

curl -X GET http://localhost:5000/users/1

3. Create New User

curl -X POST http://localhost:5000/users \
  -H "Content-Type: application/json" \
  -d '{"name": "Alice Johnson", "email": "alice@example.com"}'

Response:

{
  "status": "success",
  "message": "User created successfully",
  "data": {
    "id": 3,
    "name": "Alice Johnson",
    "email": "alice@example.com",
    "created_at": "2024-09-16"
  }
}

4. Update User

curl -X PUT http://localhost:5000/users/1 \
  -H "Content-Type: application/json" \
  -d '{"name": "John Updated", "email": "john.updated@example.com"}'

5. Delete User

curl -X DELETE http://localhost:5000/users/1

Testing with Postman

1. Import Collection: Create a new collection in Postman
2. Set Base URL: http://localhost:5000
3. Test Each Endpoint:
   • GET /users - No body required
   • POST /users - Set Content-Type to application/json, add body with name and email
   • PUT /users/1 - Same as POST, but update existing user
   • DELETE /users/1 - No body required

HTTP Status Codes Used

• 200 OK: Successful GET, PUT requests
• 201 Created: Successful POST request
• 400 Bad Request: Invalid JSON or missing required fields
• 404 Not Found: User not found or invalid endpoint
• 405 Method Not Allowed: Invalid HTTP method for endpoint
• 409 Conflict: Email already exists

Data Structure

User Object

{
  "id": 1,
  "name": "John Doe",
  "email": "john@example.com",
  "created_at": "2024-01-15"
}

API Response Format

{
  "status": "success|error",
  "message": "Description message",
  "data": "Actual data object/array",
  "count": "Number of items (for lists)"
}

Key Concepts Demonstrated

1. REST Architecture: Resource-based URLs, HTTP methods
2. Flask Routing: Different routes for different operations
3. JSON Handling: request.get_json() and jsonify()
4. HTTP Methods: GET, POST, PUT, DELETE
5. Status Codes: Appropriate codes for different scenarios
6. Error Handling: Try-catch blocks and error responses
7. Data Validation: Required field checking, duplicate prevention
8. In-Memory Storage: List and dictionary data structures

Interview Questions Covered

1. What is Flask? - Lightweight Python web framework
2. What is REST? - Representational State Transfer architectural style
3. GET vs POST? - GET retrieves data, POST creates data
4. Flask Routes - @app.route() decorator maps URLs to functions
5. request.json - Accesses JSON data from HTTP request body
6. Status Codes - 200 (success), 404 (not found), 201 (created), etc.
7. Running Flask - python app.py or flask run
8. JSON - JavaScript Object Notation, lightweight data format
9. API Testing - Using curl, Postman, or browser dev tools
10. Database Alternative - Yes, can use SQLite, PostgreSQL, MongoDB instead of in-memory storage

Future Enhancements

• Add database integration (SQLite/PostgreSQL)
• Implement authentication and authorization
• Add input sanitization and validation
• Include pagination for large datasets
• Add logging and monitoring
• Create unit tests

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request

License

This project is open source and available under the MIT License.

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Author: [Your Name]
Date: September 2024
Purpose: Flask REST API learning project