Django

Quick Start

views.py

from rest_framework import viewsets from rest_framework.decorators import api_view from rest_framework.response import Response

@api_view(['GET']) def health_check(request): return Response({'status': 'ok'})

class UserViewSet(viewsets.ModelViewSet): queryset = User.objects.all() serializer_class = UserSerializer

Features

Feature Description Guide

Models ORM, relationships, managers MODELS.md

Views ViewSets, APIView, async views VIEWS.md

Serializers Validation, nested data SERIALIZERS.md

Auth JWT, permissions, policies AUTH.md

Queries select_related, prefetch, N+1 QUERIES.md

Testing pytest-django, fixtures TESTING.md

Common Patterns

Model with Relationships

from django.db import models from uuid import uuid4

class User(AbstractUser): id = models.UUIDField(primary_key=True, default=uuid4, editable=False) email = models.EmailField(unique=True)

USERNAME_FIELD = 'email'

class Meta:
    db_table = 'users'
    indexes = [models.Index(fields=['email'])]

class Organization(models.Model): id = models.UUIDField(primary_key=True, default=uuid4, editable=False) name = models.CharField(max_length=255) slug = models.SlugField(unique=True) owner = models.ForeignKey(User, on_delete=models.PROTECT, related_name='owned_orgs') members = models.ManyToManyField(User, through='Membership', related_name='organizations')

DRF Serializers

from rest_framework import serializers

class UserSerializer(serializers.ModelSerializer): full_name = serializers.SerializerMethodField()

class Meta:
    model = User
    fields = ['id', 'email', 'full_name', 'created_at']
    read_only_fields = ['id', 'created_at']

def get_full_name(self, obj):
    return f"{obj.first_name} {obj.last_name}".strip()

class UserCreateSerializer(serializers.ModelSerializer): password = serializers.CharField(write_only=True, min_length=8) password_confirm = serializers.CharField(write_only=True)

class Meta:
    model = User
    fields = ['email', 'password', 'password_confirm']

def validate(self, attrs):
    if attrs['password'] != attrs['password_confirm']:
        raise serializers.ValidationError({'password_confirm': 'Passwords must match'})
    return attrs

def create(self, validated_data):
    validated_data.pop('password_confirm')
    return User.objects.create_user(**validated_data)

ViewSet with Permissions

from rest_framework import viewsets, permissions from rest_framework.decorators import action from rest_framework.response import Response

class UserViewSet(viewsets.ModelViewSet): permission_classes = [permissions.IsAuthenticated]

def get_queryset(self):
    return User.objects.select_related('profile').prefetch_related('organizations')

def get_serializer_class(self):
    if self.action == 'create':
        return UserCreateSerializer
    return UserSerializer

@action(detail=False, methods=['get', 'patch'])
def me(self, request):
    if request.method == 'GET':
        return Response(UserSerializer(request.user).data)
    serializer = UserSerializer(request.user, data=request.data, partial=True)
    serializer.is_valid(raise_exception=True)
    serializer.save()
    return Response(serializer.data)

Workflows

API Development

• Create model and migration

• Create serializer with validation

• Create ViewSet or APIView

• Configure URL routing

• Write tests with pytest-django

Query Optimization

Avoid N+1 queries

users = User.objects.select_related('profile').prefetch_related( Prefetch('organizations', queryset=Organization.objects.only('id', 'name')) )

Use values() for lightweight queries

User.objects.values('id', 'email', 'created_at')

Annotate for aggregations

Organization.objects.annotate(member_count=Count('members'))

Best Practices

Do Avoid

Use select_related /prefetch_related

N+1 queries

Use serializers for validation Manual validation

Use custom managers Query logic in views

Use signals sparingly Overusing signals

Use Celery for heavy tasks Sync operations for I/O

Project Structure

project/ ├── manage.py ├── config/ │ ├── settings/ │ ├── urls.py │ └── wsgi.py ├── apps/ │ ├── users/ │ │ ├── models.py │ │ ├── serializers.py │ │ ├── views.py │ │ └── tests/ │ └── organizations/ ├── common/ │ ├── permissions.py │ └── pagination.py └── tests/

For detailed examples and patterns, see reference files above.