django-patterns

Use a config package with split settings files (base.py, development.py, production.py, test.py) and organize business logic into an apps directory. Each app contains models, views, serializers, services, and tests for clear separation of concerns.

Use select_related for foreign key relationships and prefetch_related for many-to-many fields when querying. Encapsulate these in custom QuerySet methods like with_category() so optimization is applied consistently across the codebase.

The service layer pattern moves business logic out of views and models into dedicated service classes, such as an OrderService handling order creation and payment processing. This keeps views thin and makes complex operations testable and reusable.

Yes, use the @action decorator to add custom endpoints to ViewSets, such as a purchase action on a product or a featured list endpoint. Actions support detail routes, custom HTTP methods, and per-action permission classes.

Signals suit decoupled side effects like creating a user profile on user registration via post_save. For core business flows, direct service method calls are preferable because signals can obscure execution order and complicate debugging.