🧩 7-BO‘LIM: Django, DRF, FastAPI – Framework Specific savollar va javoblar

🔹 Django

1. Django’da signal’lar bilan nima qilgansan?

post_save, pre_save, post_delete signal’lari bilan Profile yaratish, admin notificatsiya, va audit log yozish uchun ishlaganman.

@receiver(post_save, sender=User)
def create_profile(sender, instance, created, **kwargs):
    if created:
        Profile.objects.create(user=instance)

2. Middleware’lar qanday ishlaydi va nima uchun kerak?

Request va response oqimini intercept qiladi.
Authentication, Rate limiting, Logging, Multi-tenant switch uchun ishlatiladi.

class MyCustomMiddleware:
    def __call__(self, request):
        print("Before view")
        response = self.get_response(request)
        print("After view")
        return response

3. Django’da OneToOne, ForeignKey, ManyToMany farqi?

Field	Relationship	Access
OneToOneField	1:1	`.relatedname`
ForeignKey	Many:1	`.model_set`
ManyToMany	Many:Many	`.all()`

4. select_for_update() qachon ishlatiladi?

Transaction ichida row’ni lock qilish uchun (deadlock yoki race condition’ga qarshi)

with transaction.atomic():
    user = User.objects.select_for_update().get(id=1)
    user.balance -= 100
    user.save()

5. Meta: unique_together vs UniqueConstraint?

Django 3.2+ dan UniqueConstraint ishlatiladi, bu aniqroq:

class Meta:
    constraints = [
        models.UniqueConstraint(fields=['user', 'course'], name='unique_user_course')
    ]

🔹 DRF (Django REST Framework)

6. Serializer’larda .create() va .update() metodlari qachon kerak?

ModelSerializer default o‘zi bajaradi
Custom logic kerak bo‘lsa override qilinadi

class UserSerializer(serializers.ModelSerializer):
    def create(self, validated_data):
        password = validated_data.pop("password")
        user = User(**validated_data)
        user.set_password(password)
        user.save()
        return user

7. DRF permission’lari haqida?

IsAuthenticated, IsAdminUser, AllowAny
Custom:

class IsOwner(permissions.BasePermission):
    def has_object_permission(self, request, view, obj):
        return obj.user == request.user

8. APIView vs GenericAPIView vs ViewSet farqlari?

Class	Use case
`APIView`	full manual control
`GenericAPIView`	mixin bilan ishlaydi
`ViewSet`	RESTful endpointlar uchun

9. @action dekoratori nima?

ViewSet ichida non-CRUD endpoint yaratish:

@action(detail=True, methods=["post"])
def activate(self, request, pk=None):
    ...

10. Filtering, Search, Ordering qanday qo‘shiladi?

class MyViewSet(viewsets.ModelViewSet):
    filter_backends = [DjangoFilterBackend, SearchFilter, OrderingFilter]
    filterset_fields = ['status']
    search_fields = ['title', 'description']
    ordering_fields = ['created_at']

🔹 FastAPI

11. FastAPI’da dependency injection qanday ishlaydi?

def get_db():
    db = Session()
    try:
        yield db
    finally:
        db.close()

@app.get("/users/")
def read_users(db: Session = Depends(get_db)):
    return db.query(User).all()

Depends() orqali requestda kerakli resurslar inject qilinadi

12. FastAPI’dagi Pydantic modellar va ORM mode?

class User(BaseModel):
    id: int
    name: str

    class Config:
        orm_mode = True

orm_mode = True → SQLAlchemy instance’ni JSON response’ga avtomatik o‘girish

13. Background tasklar qanday qo‘shiladi?

from fastapi import BackgroundTasks

def send_email(email: str):
    ...

@app.post("/register/")
def register_user(email: str, bg: BackgroundTasks):
    bg.add_task(send_email, email)

14. FastAPI + SQLAlchemy + Alembic migratsiyasi haqida?

alembic init migrations
alembic revision --autogenerate -m "add users"
alembic upgrade head

FastAPI loyihalarida models/, schemas/, routers/ folderlar bilan modular DDD structure afzal.

15. FastAPI vs DRF – qachon qaysi biri?

Criteria	DRF	FastAPI
Maturity	Juda katta	Nisbatan yangi
Async support	Limited	Native async
Performance	O‘rtacha	Yuqori (Starlette)
ORM support	Django ORM only	SQLAlchemy / others
Swagger	Custom	Auto generated, kuchli