Backend.md

Backend Documentation

Overview

The backend is built with:

• FastAPI
• PostgreSQL
• SQLAlchemy
• Alembic (migrations)
• Python 3.12+

Project Structure

backend/
├── app/
│   ├── api/           # API endpoints
│   ├── core/          # Core functionality
│   ├── db/            # Database models and migrations
│   ├── schemas/       # Pydantic models
│   ├── services/      # Business logic
│   └── main.py        # Application entry point
├── tests/             # Test suite
├── alembic/           # Database migrations
├── requirements.txt   # Python dependencies
└── Dockerfile        # Docker configuration

Development

Environment Variables

Required environment variables:

# Database
DATABASE_URL=postgresql+asyncpg://user:password@localhost:5432/dd_db

# Google OAuth
GOOGLE_CLIENT_ID=your_google_client_id
GOOGLE_CLIENT_SECRET=your_google_client_secret

# Security
SECRET_KEY=your_random_secret_key

# URLs
BASE_URL=http://localhost:56000
FRONTEND_URL=http://localhost:54287

Database Setup

1. Create database:

   psql -c "CREATE DATABASE dd_db;"

2. Run migrations:

   alembic upgrade head

3. Seed initial data:

   python -m app.db.seed

Running Tests

# Run all tests
pytest

# Run with coverage
pytest --cov=app

# Run specific test file
pytest tests/test_api.py

API Implementation

Authentication

OAuth implementation:

• app/api/auth.py - Authentication endpoints
• app/core/auth.py - Authentication logic
• app/core/security.py - Security utilities

Database Models

Key models:

• app/db/models/user.py - User model
• app/db/models/task.py - Task model
• app/db/models/contract.py - Contract model
• app/db/models/wallet.py - Wallet model

API Endpoints

Endpoint implementation:

• app/api/tasks.py - Task endpoints
• app/api/contracts.py - Contract endpoints
• app/api/wallets.py - Wallet endpoints

Business Logic

Service layer:

• app/services/task.py - Task service
• app/services/contract.py - Contract service
• app/services/wallet.py - Wallet service

Database Migrations

Using Alembic for migrations:

# Create new migration
alembic revision --autogenerate -m "description"

# Apply migrations
alembic upgrade head

# Rollback migration
alembic downgrade -1

Scheduled Tasks

Automatic contract processing:

• app/core/scheduler.py - Task scheduler
• app/services/contract_processor.py - Contract processing logic

Security

Security measures:

1. Authentication:

   • OAuth 2.0 with Google
   • JWT session tokens
   • CSRF protection

2. Authorization:

   • Role-based access control
   • Parent/child permissions

3. Data Protection:

   • Input validation
   • SQL injection prevention
   • XSS protection

4. Rate Limiting:

   • API rate limiting
   • Brute force protection

Error Handling

Error handling implementation:

• app/core/exceptions.py - Custom exceptions
• app/core/error_handlers.py - Error handlers

Logging

Logging configuration:

• app/core/logging.py - Logging setup
• Application logs
• Access logs
• Error logs

Testing

Test implementation:

• Unit tests
• Integration tests
• API tests
• Database tests

Performance

Performance optimizations:

1. Database:

   • Connection pooling
   • Query optimization
   • Indexing strategy

2. Caching:

   • Response caching
   • Query result caching

3. Async Implementation:

   • Async database operations
   • Async API endpoints

Monitoring

Monitoring setup:

1. Health checks
2. Performance metrics
3. Error tracking
4. Resource usage

Deployment

Deployment configurations:

1. Docker setup
2. Production settings
3. SSL/TLS configuration
4. Backup strategy