django

Generate production-grade Django code following official best practices.

Workflow

Step 1: Understand Requirements

Identify what the user needs:

• Models/ORM: Data modeling, relationships, queries, migrations
• Views: Function-based (FBV) or class-based (CBV), API responses
• URLs: Routing, converters, namespaces, includes
• Forms: Validation, ModelForm, formsets, widgets
• Admin: ModelAdmin, customization, inlines, actions
• Auth: Users, permissions, groups, decorators
• Config: Settings, middleware, deployment, ASGI/WSGI

Step 2: Choose Pattern

| Need | Pattern | When | |------|---------|------| | CRUD pages | Generic CBVs (ListView, DetailView, CreateView, UpdateView, DeleteView) | Standard model operations | | Custom logic | Function-based views | Complex workflows, non-standard responses | | API endpoints | JsonResponse + FBV or DRF | REST API without templates | | Data modeling | Models + Managers + QuerySets | Database schema design | | Background tasks | Celery + Django | Async processing | | Real-time | Django Channels | WebSockets, SSE | | Full-text search | SearchVector + SearchQuery | PostgreSQL text search |

Step 3: Generate Code

Apply Django conventions:

• Fat models, thin views (business logic in models/managers)
• Use get_object_or_404() not manual try/except
• Prefer reverse() and named URLs over hardcoded paths
• Use class-based views for standard CRUD, FBVs for custom logic
• Always validate with forms/serializers at boundaries

Step 4: Validate

Check against Django best practices:

• [ ] Models have __str__() and Meta class
• [ ] Views handle GET/POST correctly
• [ ] URLs use path() with typed converters
• [ ] Forms validate all user input
• [ ] Settings split: base, dev, production
• [ ] No raw SQL unless absolutely necessary
• [ ] Migrations are forward-compatible
• [ ] Admin registered for all models

Step 5: Optimize

Apply performance patterns:

• select_related() for FK, prefetch_related() for M2M
• only() / defer() for partial field loading
• Database indexes on filtered/ordered fields
• QuerySet.iterator() for large result sets
• Cache with @cache_page or low-level cache API
• bulk_create() / bulk_update() for batch operations

Quick Reference

| Task | Code | |------|------| | New project | django-admin startproject mysite | | New app | python manage.py startapp myapp | | Run server | python manage.py runserver | | Make migrations | python manage.py makemigrations | | Apply migrations | python manage.py migrate | | Create superuser | python manage.py createsuperuser | | Shell | python manage.py shell | | Collect static | python manage.py collectstatic | | Run tests | python manage.py test | | Check deployment | python manage.py check --deploy |

Must Avoid

• N+1 queries: Always use select_related() / prefetch_related()
• Logic in views: Move business logic to models or services
• Hardcoded URLs: Use reverse() and {% url %} tag
• Raw user input in queries: Use ORM or parameterized queries
• settings.py for secrets: Use environment variables
• DEBUG=True in production: Split settings by environment
• Ignoring migrations: Always create and apply migrations
• objects.all() in templates: Query in views, pass via context

Performance Tips

| Tip | Impact | |-----|--------| | select_related / prefetch_related | Eliminates N+1 queries | | Database indexes | 10-100x faster filtered queries | | only() / defer() | Reduces memory for large models | | iterator() | Streams large querysets | | bulk_create / bulk_update | Batch DB operations | | Template fragment caching | Reduces template rendering time | | @cache_page decorator | Full page caching |

Reference Files

| File | Content | |------|---------| | models-orm.md | Models, fields, relationships, querysets, managers | | views.md | FBVs, CBVs, generic views, mixins, async views | | urls-routing.md | URL patterns, converters, namespaces, includes | | forms-admin.md | Forms, ModelForm, formsets, admin customization | | settings-deployment.md | Settings, middleware, security, ASGI/WSGI, deployment |