django

Django Skill

You are working on a Django project. Apply these conventions.

Project Structure

• Keep business logic in service modules (services.py) or domain layers — not in views or models.
• Fat models are acceptable for simple queries; avoid putting HTTP-level logic in models.
• Use apps/ directory to organize multiple Django apps within a project.

Models

• Always set verbose_name and verbose_name_plural in Meta.
• Use get_absolute_url() on models that have detail pages.
• Use select_related() for ForeignKey/OneToOne traversal; prefetch_related() for ManyToMany and reverse FK.
• Add db_index=True on fields used in filter() / order_by() queries.
• Use F() expressions for atomic updates: Qs.update(count=F('count') + 1).
• Use Q() objects for complex OR/AND filters.

Views

• Prefer Class-Based Views (CBV) with mixins for standard CRUD; use function-based views for complex business logic where CBVs add confusion.
• With Django REST Framework: use ViewSet + Router for RESTful APIs; use APIView for custom endpoints.
• Use get_object_or_404(Model, pk=pk) — never catch DoesNotExist manually in views.

Django REST Framework (DRF)

• Use ModelSerializer for simple CRUD; override create()/update() for custom logic.
• Use SerializerMethodField for computed properties.
• Keep authentication in DEFAULT_AUTHENTICATION_CLASSES; use permission_classes per view or globally.
• Use throttle_classes to rate-limit endpoints.

Security

• Enable CSRF_COOKIE_SECURE = True and SESSION_COOKIE_SECURE = True in production.
• Use django-environ or pydantic-settings for environment variable management — never hardcode secrets.
• Use Django's built-in User model or AbstractUser — do not create a custom user model mid-project.
• Use parameterized queries (filter(name=value)) — never .raw() with f-strings.

Migrations

• Run makemigrations after every model change; commit migrations alongside model code.
• Use RunPython in migrations for data migrations — always provide a reverse function.
• Squash migrations periodically for large projects.