mirror of
https://github.com/duthaho/claudekit.git
synced 2026-07-28 23:51:02 +03:00
feat: adding new skills, including testing patterns and methodologies, along with bundled resources for better usability.
This commit is contained in:
duthaho
@@ -0,0 +1,250 @@
|
||||
# Django Patterns Quick Reference
|
||||
|
||||
## QuerySet Patterns
|
||||
|
||||
### select_related (FK/OneToOne - single JOIN)
|
||||
|
||||
```python
|
||||
# BAD: N+1 queries
|
||||
for order in Order.objects.all():
|
||||
print(order.customer.name) # Hits DB each iteration
|
||||
|
||||
# GOOD: 1 query with JOIN
|
||||
for order in Order.objects.select_related("customer"):
|
||||
print(order.customer.name)
|
||||
|
||||
# Chain through multiple FKs
|
||||
Order.objects.select_related("customer__company")
|
||||
```
|
||||
|
||||
### prefetch_related (M2M/reverse FK - separate query)
|
||||
|
||||
```python
|
||||
# BAD: N+1 on reverse FK
|
||||
for author in Author.objects.all():
|
||||
print(author.book_set.all()) # Query per author
|
||||
|
||||
# GOOD: 2 queries total
|
||||
for author in Author.objects.prefetch_related("books"):
|
||||
print(author.books.all())
|
||||
|
||||
# Custom prefetch with filtering
|
||||
from django.db.models import Prefetch
|
||||
|
||||
Author.objects.prefetch_related(
|
||||
Prefetch("books", queryset=Book.objects.filter(published=True), to_attr="published_books")
|
||||
)
|
||||
```
|
||||
|
||||
### F Objects (reference model fields in queries)
|
||||
|
||||
```python
|
||||
from django.db.models import F
|
||||
|
||||
Product.objects.filter(stock__lt=F("reorder_level")) # Compare fields
|
||||
Product.objects.filter(id=1).update(stock=F("stock") - 1) # Atomic update
|
||||
Order.objects.filter(amount__gt=F("customer__credit_limit")) # Across relations
|
||||
```
|
||||
|
||||
### Q Objects (complex lookups with OR/NOT)
|
||||
|
||||
```python
|
||||
from django.db.models import Q
|
||||
|
||||
# OR
|
||||
User.objects.filter(Q(role="admin") | Q(is_superuser=True))
|
||||
|
||||
# NOT
|
||||
User.objects.filter(~Q(status="banned"))
|
||||
|
||||
# Complex combinations
|
||||
User.objects.filter(
|
||||
(Q(role="admin") | Q(role="staff")) & ~Q(status="inactive")
|
||||
)
|
||||
|
||||
# Dynamic query building
|
||||
conditions = Q()
|
||||
if name: conditions &= Q(name__icontains=name)
|
||||
if email: conditions &= Q(email__icontains=email)
|
||||
User.objects.filter(conditions)
|
||||
```
|
||||
|
||||
### Subquery and OuterRef
|
||||
|
||||
```python
|
||||
from django.db.models import Subquery, OuterRef, Exists
|
||||
|
||||
# Subquery: latest order date per customer
|
||||
latest_order = Order.objects.filter(
|
||||
customer=OuterRef("pk")
|
||||
).order_by("-created_at").values("created_at")[:1]
|
||||
|
||||
Customer.objects.annotate(last_order=Subquery(latest_order))
|
||||
|
||||
# Exists: customers with orders
|
||||
Customer.objects.annotate(
|
||||
has_orders=Exists(Order.objects.filter(customer=OuterRef("pk")))
|
||||
).filter(has_orders=True)
|
||||
```
|
||||
|
||||
### Aggregation
|
||||
|
||||
```python
|
||||
from django.db.models import Count, Sum, Avg
|
||||
|
||||
# Aggregate (returns dict)
|
||||
Order.objects.aggregate(total=Sum("amount"), avg=Avg("amount"))
|
||||
|
||||
# Annotate (per-row)
|
||||
Customer.objects.annotate(order_count=Count("orders"))
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## Model Patterns
|
||||
|
||||
### Abstract Base Model
|
||||
|
||||
```python
|
||||
class TimestampMixin(models.Model):
|
||||
created_at = models.DateTimeField(auto_now_add=True)
|
||||
updated_at = models.DateTimeField(auto_now=True)
|
||||
|
||||
class Meta:
|
||||
abstract = True # No DB table created
|
||||
|
||||
class Order(TimestampMixin):
|
||||
amount = models.DecimalField(max_digits=10, decimal_places=2)
|
||||
# Inherits created_at, updated_at
|
||||
```
|
||||
|
||||
### Proxy Model (same table, different behavior)
|
||||
|
||||
```python
|
||||
class PendingOrderManager(models.Manager):
|
||||
def get_queryset(self):
|
||||
return super().get_queryset().filter(status="pending")
|
||||
|
||||
class PendingOrder(Order):
|
||||
objects = PendingOrderManager()
|
||||
class Meta:
|
||||
proxy = True # Same DB table as Order
|
||||
```
|
||||
|
||||
### Custom Manager and QuerySet
|
||||
|
||||
```python
|
||||
class PublishedQuerySet(models.QuerySet):
|
||||
def published(self):
|
||||
return self.filter(status="published")
|
||||
|
||||
def by_author(self, author):
|
||||
return self.filter(author=author)
|
||||
|
||||
class Article(models.Model):
|
||||
objects = PublishedQuerySet.as_manager()
|
||||
|
||||
# Chainable: Article.objects.published().by_author(user)
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## View Patterns
|
||||
|
||||
### Class-Based View Mixins
|
||||
|
||||
| Mixin | Purpose |
|
||||
|-------|---------|
|
||||
| `LoginRequiredMixin` | Require authentication |
|
||||
| `PermissionRequiredMixin` | Require specific permission |
|
||||
| `UserPassesTestMixin` | Custom permission test |
|
||||
| `FormView` | Handle form display + submission |
|
||||
| `CreateView` / `UpdateView` | Model form CRUD |
|
||||
| `ListView` / `DetailView` | Read operations |
|
||||
|
||||
```python
|
||||
class OrderListView(LoginRequiredMixin, PermissionRequiredMixin, ListView):
|
||||
model = Order
|
||||
permission_required = "orders.view_order"
|
||||
paginate_by = 25
|
||||
|
||||
def get_queryset(self):
|
||||
return super().get_queryset().filter(customer=self.request.user)
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## Django REST Framework Patterns
|
||||
|
||||
### Nested Serializers
|
||||
|
||||
```python
|
||||
class AddressSerializer(serializers.ModelSerializer):
|
||||
class Meta:
|
||||
model = Address
|
||||
fields = ["street", "city", "zip_code"]
|
||||
|
||||
class CustomerSerializer(serializers.ModelSerializer):
|
||||
address = AddressSerializer()
|
||||
|
||||
class Meta:
|
||||
model = Customer
|
||||
fields = ["id", "name", "address"]
|
||||
|
||||
def create(self, validated_data):
|
||||
address_data = validated_data.pop("address")
|
||||
address = Address.objects.create(**address_data)
|
||||
return Customer.objects.create(address=address, **validated_data)
|
||||
```
|
||||
|
||||
### Custom Permissions
|
||||
|
||||
```python
|
||||
from rest_framework.permissions import BasePermission
|
||||
|
||||
class IsOwner(BasePermission):
|
||||
def has_object_permission(self, request, view, obj):
|
||||
return obj.owner == request.user
|
||||
|
||||
class IsAdminOrReadOnly(BasePermission):
|
||||
def has_permission(self, request, view):
|
||||
if request.method in ("GET", "HEAD", "OPTIONS"):
|
||||
return True
|
||||
return request.user.is_staff
|
||||
|
||||
# Usage
|
||||
class OrderViewSet(viewsets.ModelViewSet):
|
||||
permission_classes = [IsAuthenticated, IsOwner]
|
||||
```
|
||||
|
||||
### ViewSet Actions
|
||||
|
||||
```python
|
||||
from rest_framework.decorators import action
|
||||
|
||||
class OrderViewSet(viewsets.ModelViewSet):
|
||||
queryset = Order.objects.all()
|
||||
serializer_class = OrderSerializer
|
||||
|
||||
@action(detail=True, methods=["post"])
|
||||
def cancel(self, request, pk=None):
|
||||
order = self.get_object()
|
||||
order.cancel()
|
||||
return Response({"status": "cancelled"})
|
||||
|
||||
@action(detail=False, methods=["get"])
|
||||
def summary(self, request):
|
||||
return Response(self.get_queryset().aggregate(total=Sum("amount"), count=Count("id")))
|
||||
```
|
||||
|
||||
### Filtering (django-filter)
|
||||
|
||||
```python
|
||||
class OrderFilter(django_filters.FilterSet):
|
||||
min_amount = django_filters.NumberFilter(field_name="amount", lookup_expr="gte")
|
||||
max_amount = django_filters.NumberFilter(field_name="amount", lookup_expr="lte")
|
||||
|
||||
class Meta:
|
||||
model = Order
|
||||
fields = ["status", "customer"]
|
||||
```
|
||||
Reference in New Issue
Block a user