django-expert

SKILL.md

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

Analyze requirements — Identify models, relationships, API endpoints

Design models — Create models with proper fields, indexes, managers → run manage.py makemigrations and manage.py migrate; verify schema before proceeding

Implement views — DRF viewsets or Django 5.0 async views

Validate endpoints — Confirm each endpoint returns expected status codes with a quick APITestCase or curl check before adding auth

Add auth — Permissions, JWT authentication

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.

# 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)

# 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:

Model definitions with indexes

Serializers with validation

ViewSet or views with permissions

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