FastAPI Social Media API

A simple social networking service API built with FastAPI that allows users to create, retrieve, update, and delete posts; add comments; and like/unlike posts.

Features

• Post Management: Create, read, update, delete posts
• Comment System: Add, view, update, delete comments on posts
• Like System: Like and unlike posts
• SQLite Database: Persistent storage with automatic initialization
• OpenAPI Documentation: Swagger UI and ReDoc interfaces
• CORS Support: Enabled for all origins

Project Structure

python/
├── main.py           # FastAPI application with all endpoints
├── models.py         # Pydantic models for request/response validation
├── database.py       # SQLite database operations and CRUD functions
├── requirements.txt  # Python dependencies
├── sns_api.db       # SQLite database (created automatically)
└── .venv/           # Python virtual environment

Installation & Setup

1. Create and activate virtual environment:

   cd python
   python3 -m venv .venv
   source .venv/bin/activate

2. Install dependencies:

   pip install -r requirements.txt

3. Run the application:

   python main.py

The API will be available at http://localhost:8000

API Endpoints

Posts

• GET /api/posts - List all posts
• POST /api/posts - Create a new post
• GET /api/posts/{postId} - Get a specific post
• PATCH /api/posts/{postId} - Update a post
• DELETE /api/posts/{postId} - Delete a post

Comments

• GET /api/posts/{postId}/comments - List comments for a post
• POST /api/posts/{postId}/comments - Create a comment
• GET /api/posts/{postId}/comments/{commentId} - Get a specific comment
• PATCH /api/posts/{postId}/comments/{commentId} - Update a comment
• DELETE /api/posts/{postId}/comments/{commentId} - Delete a comment

Likes

• POST /api/posts/{postId}/likes - Like a post
• DELETE /api/posts/{postId}/likes - Unlike a post

API Documentation

FastAPI automatically generates interactive API documentation in multiple formats:

1. Swagger UI - /docs

URL: http://localhost:8000/docs

Swagger UI is an interactive documentation interface that allows you to:

• 📖 Browse all available API endpoints
• 🧪 Test API calls directly from your browser (Try it out!)
• 📝 View request/response schemas and examples
• 🔍 See detailed parameter descriptions
• ✅ Execute API calls and see real responses

Use Case: Perfect for developers who want to quickly test and explore the API without writing code.

2. ReDoc - /redoc

URL: http://localhost:8000/redoc

ReDoc is a clean, reading-focused documentation interface that provides:

• 📚 A more polished, professional documentation layout
• 📊 Better for sharing with non-technical stakeholders
• 🎨 Clean, three-panel layout for easy navigation
• 📖 Optimized for reading and understanding the API structure
• 🖨️ Print-friendly documentation

Use Case: Ideal for creating user-facing documentation or sharing API specifications with clients/teams.

3. OpenAPI JSON - /openapi.json

URL: http://localhost:8000/openapi.json

The OpenAPI specification in JSON format:

• 🔧 Machine-readable API specification (OpenAPI 3.0.1 standard)
• 🤖 Used by tools to generate client SDKs, tests, and documentation
• 📋 Contains complete API contract: endpoints, schemas, responses, examples
• 🔄 Can be imported into tools like Postman, Insomnia, or API testing frameworks
• ✅ This endpoint serves the exact same specification as defined in openapi.yaml

Use Case: For programmatic access, code generation tools, API testing tools, or importing into other documentation platforms.

---

Quick Comparison:

Feature	Swagger UI (/docs)	ReDoc (/redoc)	OpenAPI JSON (/openapi.json)
Interactive Testing	✅ Yes	❌ No	❌ No
Clean UI	✅ Good	✅ Excellent	N/A
Machine Readable	❌ No	❌ No	✅ Yes
Best For	Testing & Exploration	Reading & Sharing	Tools & Integration

Example Usage

Create a Post

curl -X POST http://localhost:8000/api/posts \
  -H "Content-Type: application/json" \
  -d '{"username": "john_doe", "content": "Hello, World!"}'

Get All Posts

curl http://localhost:8000/api/posts

Add a Comment

curl -X POST http://localhost:8000/api/posts/1/comments \
  -H "Content-Type: application/json" \
  -d '{"username": "jane_smith", "content": "Great post!"}'

Like a Post

curl -X POST http://localhost:8000/api/posts/1/likes \
  -H "Content-Type: application/json" \  
  -d '{"username": "alice"}' 

Key Features Implemented

✅ FastAPI Framework: High-performance web framework
✅ SQLite Database: Lightweight, file-based database with automatic initialization
✅ Exact OpenAPI Compliance: Serves the exact OpenAPI 3.0.1 specification from openapi.yaml ✅ CORS Enabled: Configured to allow all origins for development ✅ Port 8000: Application runs on the specified port ✅ Pydantic Validation: Request/response validation with detailed error messages ✅ Database Relationships: Foreign keys and referential integrity
✅ Automatic Counts: Post like_count and comment_count updated automatically ✅ Error Handling: Comprehensive error responses with proper HTTP status codes ✅ Clean Architecture: Separated concerns with models, database operations, and API routes