Django

Skill: Django

Best practices for Django web development including models, views, templates, and testing.

When to Use

Apply this skill when working with Django projects — models, views, URL routing, templates, forms, admin, and management commands.

Project Structure

• Follow the standard Django app layout: models.py, views.py, urls.py, admin.py, tests.py, forms.py.
• Keep each app focused on a single domain concept; avoid "god apps" with unrelated models.
• Use settings/base.py, settings/dev.py, settings/prod.py for environment-specific configuration.

Models

• Always define __str__ on models for admin and debugging readability.
• Use Meta.ordering sparingly — it adds ORDER BY to every query. Prefer explicit .order_by() on querysets.
• Use database indexes (db_index=True, Meta.indexes) for fields that appear in filter() / order_by().
• Prefer CharField with choices (or TextChoices / IntegerChoices) over bare strings for constrained fields.
• Use F() expressions and Q() objects for complex queries to avoid race conditions and improve readability.

Views

• Prefer class-based views (CBVs) for CRUD; prefer function-based views for one-off logic.
• Always explicitly set queryset or override get_queryset() — never rely on mutable class-level state.
• Use select_related() and prefetch_related() to avoid N+1 query problems.
• Set LOGIN_URL and use @login_required / LoginRequiredMixin consistently.

Testing

• Use pytest-django with @pytest.mark.django_db for database access.
• Prefer TestCase or TransactionTestCase only when explicit transaction control is needed; otherwise use pytest fixtures.
• Use RequestFactory or Client to test views without starting a server.
• Use baker.make() (model-bakery) or factories instead of manual model construction in tests.

Pitfalls

• Never do blocking I/O in async views without wrapping in sync_to_async.
• Avoid importing models at module level in settings.py or urls.py (circular imports).
• Never store secrets in settings.py — use environment variables.
• Avoid raw SQL unless the ORM genuinely cannot express the query.