Django REST API Development Rules

You are an expert in Python, Django, and scalable RESTful API development.

Core Principles

• Django-First Approach: Use Django's built-in features and tools wherever possible to leverage its full capabilities
• Code Quality: Prioritize readability and maintainability; follow Django's coding style guide (PEP 8 compliance)
• Naming Conventions: Use descriptive variable and function names; adhere to naming conventions (lowercase with underscores for functions and variables)
• Modular Architecture: Structure your project in a modular way using Django apps to promote reusability and separation of concerns
• Performance Awareness: Always consider scalability and performance implications in your design decisions

Project Structure

Application Structure app_name/ ├── migrations/ # Database migration files ├── admin.py # Django admin configuration ├── apps.py # App configuration ├── models.py # Database models ├── managers.py # Custom model managers ├── signals.py # Django signals ├── tasks.py # Celery tasks (if applicable) └── init.py # Package initialization

API Structure api/ └── v1/ ├── app_name/ │ ├── urls.py # URL routing │ ├── serializers.py # Data serialization │ ├── views.py # API views │ ├── permissions.py # Custom permissions │ ├── filters.py # Custom filters │ └── validators.py # Custom validators └── urls.py # Main API URL configuration

Core Structure core/ ├── responses.py # Unified response structures ├── pagination.py # Custom pagination classes ├── permissions.py # Base permission classes ├── exceptions.py # Custom exception handlers ├── middleware.py # Custom middleware ├── logging.py # Structured logging utilities └── validators.py # Reusable validators

Configuration Structure config/ ├── settings/ │ ├── base.py # Base settings │ ├── development.py # Development settings │ ├── staging.py # Staging settings │ └── production.py # Production settings ├── urls.py # Main URL configuration └── wsgi.py # WSGI configuration

Django/Python Development Guidelines

Views and API Design

• Use Class-Based Views: Leverage Django's class-based views (CBVs) with DRF's APIViews
• RESTful Design: Follow RESTful principles strictly with proper HTTP methods and status codes
• Keep Views Light: Focus views on request handling; keep business logic in models, managers, and services
• Consistent Response Format: Use unified response structure for both success and error cases

Models and Database

• ORM First: Leverage Django's ORM for database interactions; avoid raw SQL queries unless necessary for performance
• Business Logic in Models: Keep business logic in models and custom managers
• Query Optimization: Use select_related and prefetch_related for related object fetching
• Database Indexing: Implement proper database indexing for frequently queried fields
• Transactions: Use transaction.atomic() for data consistency in critical operations

Serializers and Validation

• DRF Serializers: Use Django REST Framework serializers for data validation and serialization
• Custom Validation: Implement custom validators for complex business rules
• Field-Level Validation: Use serializer field validation for input sanitization
• Nested Serializers: Properly handle nested relationships with appropriate serializers

Authentication and Permissions

• JWT Authentication: Use djangorestframework_simplejwt for JWT token-based authentication
• Custom Permissions: Implement granular permission classes for different user roles
• Security Best Practices: Implement proper CSRF protection, CORS configuration, and input sanitization

URL Configuration

• URL Patterns: Use urlpatterns to define clean URL patterns with each path() mapping routes to views
• Nested Routing: Use include() for modular URL organization
• API Versioning: Implement proper API versioning strategy (URL-based versioning recommended)

Performance and Scalability

Query Optimization

• N+1 Problem Prevention: Always use select_related and prefetch_related appropriately
• Query Monitoring: Monitor query counts and execution time in development
• Database Connection Pooling: Implement connection pooling for high-traffic applications
• Caching Strategy: Use Django's cache framework with Redis/Memcached for frequently accessed data

Response Optimization

• Pagination: Standardize pagination across all list endpoints
• Field Selection: Allow clients to specify required fields to reduce payload size
• Compression: Enable response compression for large payloads

Error Handling and Logging

Unified Error Responses { "success": false, "message": "Error description", "errors": { "field_name": ["Specific error details"] }, "error_code": "SPECIFIC_ERROR_CODE" }

Exception Handling

• Custom Exception Handler: Implement global exception handling for consistent error responses
• Django Signals: Use Django signals to decouple error handling and post-model activities
• Proper HTTP Status Codes: Use appropriate HTTP status codes (400, 401, 403, 404, 422, 500, etc.)

Logging Strategy

• Structured Logging: Implement structured logging for API monitoring and debugging
• Request/Response Logging: Log API calls with execution time, user info, and response status
• Performance Monitoring: Log slow queries and performance bottlenecks