Affaan Mustafa Patrones de Desarrollo Django
Patrones de arquitectura Django de nivel producción para aplicaciones escalables y mantenibles.
Cuándo Activar
- Construir aplicaciones web Django
- Diseñar APIs con Django REST Framework
- Trabajar con el ORM de Django y modelos
- Configurar la estructura del proyecto Django
- Implementar caché, señales, middleware
Estructura del Proyecto
Layout Recomendado
myproject/
├── config/
│ ├── __init__.py
│ ├── settings/
│ │ ├── __init__.py
│ │ ├── base.py # Configuración base
│ │ ├── development.py # Configuración de desarrollo
│ │ ├── production.py # Configuración de producción
│ │ └── test.py # Configuración de pruebas
│ ├── urls.py
│ ├── wsgi.py
│ └── asgi.py
├── manage.py
└── apps/
├── __init__.py
├── users/
│ ├── __init__.py
│ ├── models.py
│ ├── views.py
│ ├── serializers.py
│ ├── urls.py
│ ├── permissions.py
│ ├── filters.py
│ ├── services.py
│ └── tests/
└── products/
└── ...
Patrón de Configuración Dividida
# config/settings/base.py
from pathlib import Path
BASE_DIR = Path(__file__).resolve().parent.parent.parent
SECRET_KEY = env('DJANGO_SECRET_KEY')
DEBUG = False
ALLOWED_HOSTS = []
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'rest_framework',
'rest_framework.authtoken',
'corsheaders',
# Apps locales
'apps.users',
'apps.products',
]
MIDDLEWARE = [
'django.middleware.security.SecurityMiddleware',
'whitenoise.middleware.WhiteNoiseMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'corsheaders.middleware.CorsMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
]
ROOT_URLCONF = 'config.urls'
WSGI_APPLICATION = 'config.wsgi.application'
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.postgresql',
'NAME': env('DB_NAME'),
'USER': env('DB_USER'),
'PASSWORD': env('DB_PASSWORD'),
'HOST': env('DB_HOST'),
'PORT': env('DB_PORT', default='5432'),
}
}
# config/settings/development.py
from .base import *
DEBUG = True
ALLOWED_HOSTS = ['localhost', '127.0.0.1']
DATABASES['default']['NAME'] = 'myproject_dev'
INSTALLED_APPS += ['debug_toolbar']
MIDDLEWARE += ['debug_toolbar.middleware.DebugToolbarMiddleware']
EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'
# config/settings/production.py
from .base import *
DEBUG = False
ALLOWED_HOSTS = env.list('ALLOWED_HOSTS')
SECURE_SSL_REDIRECT = True
SESSION_COOKIE_SECURE = True
CSRF_COOKIE_SECURE = True
SECURE_HSTS_SECONDS = 31536000
SECURE_HSTS_INCLUDE_SUBDOMAINS = True
SECURE_HSTS_PRELOAD = True
# Logging
LOGGING = {
'version': 1,
'disable_existing_loggers': False,
'handlers': {
'file': {
'level': 'WARNING',
'class': 'logging.FileHandler',
'filename': '/var/log/django/django.log',
},
},
'loggers': {
'django': {
'handlers': ['file'],
'level': 'WARNING',
'propagate': True,
},
},
}
Patrones de Diseño de Modelos
Buenas Prácticas de Modelos
from django.db import models
from django.contrib.auth.models import AbstractUser
from django.core.validators import MinValueValidator, MaxValueValidator
class User(AbstractUser):
"""Modelo de usuario personalizado que extiende AbstractUser."""
email = models.EmailField(unique=True)
phone = models.CharField(max_length=20, blank=True)
birth_date = models.DateField(null=True, blank=True)
USERNAME_FIELD = 'email'
REQUIRED_FIELDS = ['username']
class Meta:
db_table = 'users'
verbose_name = 'user'
verbose_name_plural = 'users'
ordering = ['-date_joined']
def __str__(self):
return self.email
def get_full_name(self):
return f"{self.first_name} {self.last_name}".strip()
class Product(models.Model):
"""Modelo de producto con configuración de campos apropiada."""
name = models.CharField(max_length=200)
slug = models.SlugField(unique=True, max_length=250)
description = models.TextField(blank=True)
price = models.DecimalField(
max_digits=10,
decimal_places=2,
validators=[MinValueValidator(0)]
)
stock = models.PositiveIntegerField(default=0)
is_active = models.BooleanField(default=True)
category = models.ForeignKey(
'Category',
related_name='products'
)
tags = models.ManyToManyField('Tag', blank=True, related_name='products')
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
class Meta:
db_table = 'products'
ordering = ['-created_at']
indexes = [
models.Index(fields=['slug']),
models.Index(fields=['-created_at']),
models.Index(fields=['category', 'is_active']),
]
constraints = [
models.CheckConstraint(
check=models.Q(price__gte=0),
name='price_non_negative'
)
]
def __str__(self):
return self.name
def save(self, *args, **kwargs):
if not self.slug:
self.slug = slugify(self.name)
super().save(*args, **kwargs)
Buenas Prácticas de QuerySet
from django.db import models
class ProductQuerySet(models.QuerySet):
"""QuerySet personalizado para el modelo Product."""
def active(self):
"""Retornar solo productos activos."""
return self.filter(is_active=True)
def with_category(self):
"""Seleccionar categoría relacionada para evitar consultas N+1."""
return self.select_related('category')
def with_tags(self):
"""Prefetch tags para relación muchos-a-muchos."""
return self.prefetch_related('tags')
def in_stock(self):
"""Retornar productos con stock > 0."""
return self.filter(stock__gt=0)
def search(self, query):
"""Buscar productos por nombre o descripción."""
return self.filter(
models.Q(name__icontains=query) |
models.Q(description__icontains=query)
)
class Product(models.Model):
# ... campos ...
objects = ProductQuerySet.as_manager() # Usar QuerySet personalizado
# Uso
Product.objects.active().with_category().in_stock()
Métodos de Manager
class ProductManager(models.Manager):
"""Manager personalizado para consultas complejas."""
def get_or_none(self, **kwargs):
"""Retornar objeto o None en lugar de DoesNotExist."""
try:
return self.get(**kwargs)
except self.model.DoesNotExist:
return None
def create_with_tags(self, name, price, tag_names):
"""Crear producto con tags asociados."""
product = self.create(name=name, price=price)
tags = [Tag.objects.get_or_create(name=name)[0] for name in tag_names]
product.tags.set(tags)
return product
def bulk_update_stock(self, product_ids, quantity):
"""Actualización masiva de stock para múltiples productos."""
return self.filter(id__in=product_ids).update(stock=quantity)
# En el modelo
class Product(models.Model):
# ... campos ...
custom = ProductManager()
Patrones de Django REST Framework
Patrones de Serializer
from rest_framework import serializers
from django.contrib.auth.password_validation import validate_password
from .models import Product, User
class ProductSerializer(serializers.ModelSerializer):
"""Serializer para el modelo Product."""
category_name = serializers.CharField(source='category.name', read_only=True)
average_rating = serializers.FloatField(read_only=True)
discount_price = serializers.SerializerMethodField()
class Meta:
model = Product
fields = [
'id', 'name', 'slug', 'description', 'price',
'discount_price', 'stock', 'category_name',
'average_rating', 'created_at'
]
read_only_fields = ['id', 'slug', 'created_at']
def get_discount_price(self, obj):
"""Calcular precio con descuento si aplica."""
if hasattr(obj, 'discount') and obj.discount:
return obj.price * (1 - obj.discount.percent / 100)
return obj.price
def validate_price(self, value):
"""Asegurar que el precio no sea negativo."""
if value < 0:
raise serializers.ValidationError("Price cannot be negative.")
return value
class ProductCreateSerializer(serializers.ModelSerializer):
"""Serializer para crear productos."""
class Meta:
model = Product
fields = ['name', 'description', 'price', 'stock', 'category']
def validate(self, data):
"""Validación personalizada para múltiples campos."""
if data['price'] > 10000 and data['stock'] > 100:
raise serializers.ValidationError(
"Cannot have high-value products with large stock."
)
return data
class UserRegistrationSerializer(serializers.ModelSerializer):
"""Serializer para registro de usuario."""
password = serializers.CharField(
write_only=True,
required=True,
validators=[validate_password],
style={'input_type': 'password'}
)
password_confirm = serializers.CharField(write_only=True, style={'input_type': 'password'})
class Meta:
model = User
fields = ['email', 'username', 'password', 'password_confirm']
def validate(self, data):
"""Validar que las contraseñas coincidan."""
if data['password'] != data['password_confirm']:
raise serializers.ValidationError({
"password_confirm": "Password fields didn't match."
})
return data
def create(self, validated_data):
"""Crear usuario con contraseña hasheada."""
validated_data.pop('password_confirm')
password = validated_data.pop('password')
user = User.objects.create(**validated_data)
user.set_password(password)
user.save()
return user
Patrones de ViewSet
from rest_framework import viewsets, status, filters
from rest_framework.decorators import action
from rest_framework.response import Response
from rest_framework.permissions import IsAuthenticated, IsAdminUser
from django_filters.rest_framework import DjangoFilterBackend
from .models import Product
from .serializers import ProductSerializer, ProductCreateSerializer
from .permissions import IsOwnerOrReadOnly
from .filters import ProductFilter
from .services import ProductService
class ProductViewSet(viewsets.ModelViewSet):
"""ViewSet para el modelo Product."""
queryset = Product.objects.select_related('category').prefetch_related('tags')
permission_classes = [IsAuthenticated, IsOwnerOrReadOnly]
filter_backends = [DjangoFilterBackend, filters.SearchFilter, filters.OrderingFilter]
filterset_class = ProductFilter
search_fields = ['name', 'description']
ordering_fields = ['price', 'created_at', 'name']
ordering = ['-created_at']
def get_serializer_class(self):
"""Retornar serializer apropiado según la acción."""
if self.action == 'create':
return ProductCreateSerializer
return ProductSerializer
def perform_create(self, serializer):
"""Guardar con contexto de usuario."""
serializer.save(created_by=self.request.user)
@action(detail=False, methods=['get'])
def featured(self, request):
"""Retornar productos destacados."""
featured = self.queryset.filter(is_featured=True)[:10]
serializer = self.get_serializer(featured, many=True)
return Response(serializer.data)
@action(detail=True, methods=['post'])
def purchase(self, request, pk=None):
"""Comprar un producto."""
product = self.get_object()
service = ProductService()
result = service.purchase(product, request.user)
return Response(result, status=status.HTTP_201_CREATED)
@action(detail=False, methods=['get'], permission_classes=[IsAuthenticated])
def my_products(self, request):
"""Retornar productos creados por el usuario actual."""
products = self.queryset.filter(created_by=request.user)
page = self.paginate_queryset(products)
serializer = self.get_serializer(page, many=True)
return self.get_paginated_response(serializer.data)
Acciones Personalizadas
from rest_framework.decorators import api_view, permission_classes
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response
@api_view(['POST'])
@permission_classes([IsAuthenticated])
def add_to_cart(request):
"""Agregar producto al carrito del usuario."""
product_id = request.data.get('product_id')
quantity = request.data.get('quantity', 1)
try:
product = Product.objects.get(id=product_id)
except Product.DoesNotExist:
return Response(
{'error': 'Product not found'},
status=status.HTTP_404_NOT_FOUND
)
cart, _ = Cart.objects.get_or_create(user=request.user)
CartItem.objects.create(
cart=cart,
product=product,
quantity=quantity
)
return Response({'message': 'Added to cart'}, status=status.HTTP_201_CREATED)
Patrón de Capa de Servicio
# apps/orders/services.py
from typing import Optional
from django.db import transaction
from .models import Order, OrderItem
class OrderService:
"""Capa de servicio para la lógica de negocio relacionada con pedidos."""
@staticmethod
@transaction.atomic
def create_order(user, cart: Cart) -> Order:
"""Crear pedido a partir del carrito."""
order = Order.objects.create(
user=user,
total_price=cart.total_price
)
for item in cart.items.all():
OrderItem.objects.create(
order=order,
product=item.product,
quantity=item.quantity,
price=item.product.price
)
# Vaciar carrito
cart.items.all().delete()
return order
@staticmethod
def process_payment(order: Order, payment_data: dict) -> bool:
"""Procesar el pago del pedido."""
# Integración con pasarela de pago
payment = PaymentGateway.charge(
amount=order.total_price,
token=payment_data['token']
)
if payment.success:
order.status = Order.Status.PAID
order.save()
# Enviar email de confirmación
OrderService.send_confirmation_email(order)
return True
return False
@staticmethod
def send_confirmation_email(order: Order):
"""Enviar email de confirmación del pedido."""
# Lógica de envío de email
pass
Estrategias de Caché
Caché a Nivel de Vista
from django.views.decorators.cache import cache_page
from django.utils.decorators import method_decorator
@method_decorator(cache_page(60 * 15), name='dispatch') # 15 minutos
class ProductListView(generic.ListView):
model = Product
template_name = 'products/list.html'
context_object_name = 'products'
Caché de Fragmentos de Plantilla
{% load cache %}
{% cache 500 sidebar %}
... contenido costoso del sidebar ...
{% endcache %}
Caché de Bajo Nivel
from django.core.cache import cache
def get_featured_products():
"""Obtener productos destacados con caché."""
cache_key = 'featured_products'
products = cache.get(cache_key)
if products is None:
products = list(Product.objects.filter(is_featured=True))
cache.set(cache_key, products, timeout=60 * 15) # 15 minutos
return products
Caché de QuerySet
from django.core.cache import cache
def get_popular_categories():
cache_key = 'popular_categories'
categories = cache.get(cache_key)
if categories is None:
categories = list(Category.objects.annotate(
product_count=Count('products')
).filter(product_count__gt=10).order_by('-product_count')[:20])
cache.set(cache_key, categories, timeout=60 * 60) # 1 hora
return categories
Señales
Patrones de Señal
# apps/users/signals.py
from django.db.models.signals import post_save
from django.dispatch import receiver
from django.contrib.auth import get_user_model
from .models import Profile
User = get_user_model()
@receiver(post_save, sender=User)
def create_user_profile(sender, instance, created, **kwargs):
"""Crear perfil cuando se crea el usuario."""
if created:
Profile.objects.create(user=instance)
@receiver(post_save, sender=User)
def save_user_profile(sender, instance, **kwargs):
"""Guardar perfil cuando se guarda el usuario."""
instance.profile.save()
# apps/users/apps.py
from django.apps import AppConfig
class UsersConfig(AppConfig):
default_auto_field = 'django.db.models.BigAutoField'
name = 'apps.users'
def ready(self):
"""Importar señales cuando la app esté lista."""
import apps.users.signals
Middleware
Middleware Personalizado
# middleware/active_user_middleware.py
import time
from django.utils.deprecation import MiddlewareMixin
class ActiveUserMiddleware(MiddlewareMixin):
"""Middleware para rastrear usuarios activos."""
def process_request(self, request):
"""Procesar request entrante."""
if request.user.is_authenticated:
# Actualizar última hora activa
request.user.last_active = timezone.now()
request.user.save(update_fields=['last_active'])
class RequestLoggingMiddleware(MiddlewareMixin):
"""Middleware para logging de requests."""
def process_request(self, request):
"""Registrar hora de inicio del request."""
request.start_time = time.time()
def process_response(self, request, response):
"""Registrar duración del request."""
if hasattr(request, 'start_time'):
duration = time.time() - request.start_time
logger.info(f'{request.method} {request.path} - {response.status_code} - {duration:.3f}s')
return response
Optimización de Rendimiento
Prevención de Consultas N+1
# Mal - consultas N+1
products = Product.objects.all()
for product in products:
print(product.category.name) # Consulta separada para cada producto
# Bien - consulta única con select_related
products = Product.objects.select_related('category').all()
for product in products:
print(product.category.name)
# Bien - Prefetch para muchos-a-muchos
products = Product.objects.prefetch_related('tags').all()
for product in products:
for tag in product.tags.all():
print(tag.name)
Indexación de Base de Datos
class Product(models.Model):
name = models.CharField(max_length=200, db_index=True)
slug = models.SlugField(unique=True)
category = models.ForeignKey('Category',
created_at = models.DateTimeField(auto_now_add=True)
class Meta:
indexes = [
models.Index(fields=['name']),
models.Index(fields=['-created_at']),
models.Index(fields=['category', 'created_at']),
]
Operaciones Masivas
# Creación masiva
Product.objects.bulk_create([
Product(name=f'Product {i}', price=10.00)
for i in range(1000)
])
# Actualización masiva
products = Product.objects.all()[:100]
for product in products:
product.is_active = True
Product.objects.bulk_update(products, ['is_active'])
# Eliminación masiva
Product.objects.filter(stock=0).delete()
Referencia Rápida
| Patrón | Descripción |
|---|---|
| Configuración dividida | Separar configuración de dev/prod/test |
| QuerySet personalizado | Métodos de consulta reutilizables |
| Capa de Servicio | Separación de lógica de negocio |
| ViewSet | Endpoints de API REST |
| Validación de Serializer | Transformación de request/response |
| select_related | Optimización de clave foránea |
| prefetch_related | Optimización de muchos-a-muchos |
| Cache first | Cachear operaciones costosas |
| Señales | Acciones basadas en eventos |
| Middleware | Procesamiento de request/response |
Recuerda: Django proporciona muchos atajos, pero para aplicaciones de producción, la estructura y organización importan más que el código conciso. Construir para la mantenibilidad.
Source: affaan-m/ECC → docs/es/skills/django-patterns/SKILL.md