django-expert

--- name: django-expert description: "Use when building Django web applications or REST APIs with Django REST Framework. Invoke when working with settings.py, models.py, manage.py, or any Django project file. Creates Django models with proper indexes, optimizes ORM queries using select_related/prefetch_related, builds DRF serializers and viewsets, and configures JWT authentication. Trigger terms: Django, DRF, Django REST Framework, Django ORM, Django model, serializer, viewset, Python web." license: MIT metadata: author: https://github.com/Jeffallan version: "1.1.0" domain: backend triggers: Django, DRF, Django REST Framework, Django ORM, Django model, serializer, viewset, Python web role: specialist scope: implementation output-format: code related-skills: fullstack-guardian, fastapi-expert, test-master --- # Django Expert Senior Django specialist with deep expertise in Django 5.0, Django REST Framework, and production-grade web applications. ## When to Use This Skill - Building Django web applications or REST APIs - Designing Django models with proper relationships - Implementing DRF serializers and viewsets - Optimizing Django ORM queries - Setting up authentication (JWT, session) - Django admin customization ## Core Workflow 1. **Analyze requirements** — Identify models, relationships, API endpoints 2. **Design models** — Create models with proper fields, indexes, managers → run `manage.py makemigrations` and `manage.py migrate`; verify schema before proceeding 3. **Implement views** — DRF viewsets or Django 5.0 async views 4. **Validate endpoints** — Confirm each endpoint returns expected status codes with a quick `APITestCase` or `curl` check before adding auth 5. **Add auth** — Permissions, JWT authentication 6. **Test** — Django TestCase, APITestCase ## Reference Guide Load detailed guidance based on context: | Topic | Reference | Load When | |-------|-----------|-----------| | Models | `references/models-orm.md` | Creating models, ORM queries, optimization | | Serializers | `references/drf-serializers.md` | DRF serializers, validation | | ViewSets | `references/viewsets-views.md` | Views, viewsets, async views | | Authentication | `references/authentication.md` | JWT, permissions, SimpleJWT | | Testing | `references/testing-django.md` | APITestCase, fixtures, factories | ## Minimal Working Example The snippet below demonstrates the core MUST DO constraints: indexed fields, `select_related`, serializer validation, and endpoint permissions. ```python # models.py from django.db import models class Article(models.Model): title = models.CharField(max_length=255, db_index=True) author = models.ForeignKey( "auth.User", on_delete=models.CASCADE, related_name="articles" ) published_at = models.DateTimeField(auto_now_add=True, db_index=True) class Meta: ordering = ["-published_at"] indexes = [models.Index(fields=["author", "published_at"])] def __str__(self): return self.title # serializers.py from rest_framework import serializers from .models import Article class ArticleSerializer(serializers.ModelSerializer): author_username = serializers.CharField(source="author.username", read_only=True) class Meta: model = Article fields = ["id", "title", "author_username", "published_at"] def validate_title(self, value): if len(value.strip()) < 3: raise serializers.ValidationError("Title must be at least 3 characters.") return value.strip() # views.py from rest_framework import viewsets, permissions from .models import Article from .serializers import ArticleSerializer class ArticleViewSet(viewsets.ModelViewSet): """ Uses select_related to avoid N+1 on author lookups. IsAuthenticatedOrReadOnly: safe methods are public, writes require auth. """ serializer_class = ArticleSerializer permission_classes = [permissions.IsAuthenticatedOrReadOnly] def get_queryset(self): return Article.objects.select_related("author").all() def perform_create(self, serializer): serializer.save(author=self.request.user) ``` ```python # tests.py from rest_framework.test import APITestCase from rest_framework import status from django.contrib.auth.models import User class ArticleAPITest(APITestCase): def setUp(self): self.user = User.objects.create_user("alice", password="pass") def test_list_public(self): res = self.client.get("/api/articles/") self.assertEqual(res.status_code, status.HTTP_200_OK) def test_create_requires_auth(self): res = self.client.post("/api/articles/", {"title": "Test"}) self.assertEqual(res.status_code, status.HTTP_403_FORBIDDEN) def test_create_authenticated(self): self.client.force_authenticate(self.user) res = self.client.post("/api/articles/", {"title": "Hello Django"}) self.assertEqual(res.status_code, status.HTTP_201_CREATED) ``` ## Constraints ### MUST DO - Use `select_related`/`prefetch_related` for related objects - Add database indexes for frequently queried fields - Use environment variables for secrets - Implement proper permissions on all endpoints - Write tests for models and API endpoints - Use Django's built-in security features (CSRF, etc.) ### MUST NOT DO - Use raw SQL without parameterization - Skip database migrations - Store secrets in settings.py - Use DEBUG=True in production - Trust user input without validation - Ignore query optimization ## Output Templates When implementing Django features, provide: 1. Model definitions with indexes 2. Serializers with validation 3. ViewSet or views with permissions 4. Brief note on query optimization ## Knowledge Reference Django 5.0, DRF, async views, ORM, QuerySet, select_related, prefetch_related, SimpleJWT, django-filter, drf-spectacular, pytest-django [Documentation](https://jeffallan.github.io/claude-skills/skills/backend/django-expert/)

[{"step":1,"action":"Identify your core model requirements. List all fields, their types, and any relationships (ForeignKey, ManyToManyField, etc.) you need for your Django model.","tip":"Use Django's field types appropriately - CharField for strings, DecimalField for prices, DateField for dates, etc. Consider adding help_text for API documentation."},{"step":2,"action":"Specify your Django and DRF versions. This ensures the generated code uses compatible features and syntax.","tip":"Check your requirements.txt or pyproject.toml for exact versions. If unsure, use 'latest stable' or omit the version parameter."},{"step":3,"action":"Provide additional context about your project. Mention any specific requirements like authentication, pagination needs, or special filtering.","tip":"Include details about your deployment environment (PostgreSQL vs SQLite) as this affects some model field choices."},{"step":4,"action":"Review the generated code. Test the model migrations, serializer validation, and API endpoints in your development environment.","tip":"Use Django's shell_plus (from django-extensions) to test complex queries before implementing them in views."},{"step":5,"action":"Iterate and refine. Add custom methods, signals, or validators as needed. Consider adding Django REST Framework's search and filter backends for complex queries.","tip":"For production use, add proper permissions, throttling, and rate limiting to your viewsets."}]