Django Architecture Patterns

Django Architecture

• Fat Models, Thin Views: Put business logic in models or service classes, not views. Views handle HTTP logic only. If a view method exceeds 20 lines, extract business logic to a service
• Service Layer: services.py — class UserService: def register_user(data): create user, send welcome email, create profile. Services coordinate between models, external APIs, and business rules
• Repository Pattern: Wrap QuerySets in repository classes — class UserRepository: def find_active() returns User.objects.filter(active=True). Abstracts database queries from business logic
• Django Apps vs Modules: One Django app per bounded context — users app, orders app, payments app. Each app has its own models, views, serializers, tests. Avoid circular imports between apps
• Signals vs Direct Calls: Signals (post_save, pre_delete) for loose coupling between apps. Direct method calls for tight coupling within an app. Don't overuse signals — they make debugging harder
• Settings Management: django-environ for environment variables. Split settings: base.py + development.py + production.py + testing.py. Never commit secrets to version control