name: django-api-debugger description: Debug Django REST Framework API issues including serializers, viewsets, permissions, pagination, filtering, and response formatting. Use when troubleshooting API endpoints, serialization errors, permission denials, or unexpected response data. allowed-tools: Read, Grep, Glob

Django API Debugger

Analyzes and debugs Django REST Framework API issues in this project.

Project Context

• Backend: Django 5.x with Django REST Framework
• API base path: /api/v1/
• Key apps: core/projects, core/users, core/tools
• Serializers located in: */serializers.py
• Views located in: */views.py
• URL routing: */urls.py

When to Use

• "API returning wrong data"
• "Serializer not including field"
• "Permission denied on endpoint"
• "Pagination not working"
• "Filter not applying"
• "API response format incorrect"

Debugging Approach

1. Identify the Endpoint

• Check urls.py for URL pattern
• Find the corresponding view/viewset

2. Check the Serializer

• Verify fields are included
• Check read_only and write_only settings
• Look for custom to_representation or to_internal_value
• Verify nested serializers

3. Check the View

• Verify queryset and get_queryset()
• Check permission_classes
• Look for custom get_serializer_context()
• Verify pagination settings

4. Common Issues

Missing fields in response:

• Field not in serializer's fields
• Field is write_only=True
• Property not defined on model

Permission errors:

• Missing or incorrect permission_classes
• User not authenticated
• Object-level permissions failing

Pagination issues:

• Check DEFAULT_PAGINATION_CLASS in settings
• Verify page_size parameter
• Check for next/previous URLs in response

Key Files to Check

core/
├── projects/
│   ├── serializers.py  # Project serializers
│   ├── views.py        # Project viewsets
│   └── urls.py         # Project URL patterns
├── users/
│   ├── serializers.py  # User serializers
│   └── views.py        # User viewsets
└── tools/
    ├── serializers.py  # Tool serializers
    └── views.py        # Tool viewsets

Testing Tips

# Test endpoint directly
docker compose exec web python manage.py shell
>>> from core.projects.models import Project
>>> Project.objects.first().__dict__

# Check serializer output
>>> from core.projects.serializers import ProjectSerializer
>>> ProjectSerializer(Project.objects.first()).data