Django Expert

# Authentication

## SimpleJWT Setup

```python
# settings.py
INSTALLED_APPS = [
    ...
    'rest_framework_simplejwt',
]

REST_FRAMEWORK = {
    'DEFAULT_AUTHENTICATION_CLASSES': [
        'rest_framework_simplejwt.authentication.JWTAuthentication',
    ],
}

from datetime import timedelta

SIMPLE_JWT = {
    'ACCESS_TOKEN_LIFETIME': timedelta(minutes=15),
    'REFRESH_TOKEN_LIFETIME': timedelta(days=7),
    'ROTATE_REFRESH_TOKENS': True,
    'BLACKLIST_AFTER_ROTATION': True,
    'AUTH_HEADER_TYPES': ('Bearer',),
}

# urls.py
from rest_framework_simplejwt.views import (
    TokenObtainPairView,
    TokenRefreshView,
)

urlpatterns = [
    path('api/token/', TokenObtainPairView.as_view(), name='token_obtain_pair'),
    path('api/token/refresh/', TokenRefreshView.as_view(), name='token_refresh'),
]
```

## Custom Token Claims

```python
from rest_framework_simplejwt.serializers import TokenObtainPairSerializer
from rest_framework_simplejwt.views import TokenObtainPairView

class CustomTokenObtainPairSerializer(TokenObtainPairSerializer):
    @classmethod
    def get_token(cls, user):
        token = super().get_token(user)
        # Add custom claims
        token['email'] = user.email
        token['role'] = user.role
        return token

class CustomTokenObtainPairView(TokenObtainPairView):
    serializer_class = CustomTokenObtainPairSerializer
```

## Custom Permissions

```python
from rest_framework import permissions

class IsOwnerOrReadOnly(permissions.BasePermission):
    def has_object_permission(self, request, view, obj):
        if request.method in permissions.SAFE_METHODS:
            return True
        return obj.created_by == request.user

class IsAdminOrReadOnly(permissions.BasePermission):
    def has_permission(self, request, view):
        if request.method in permissions.SAFE_METHODS:
            return True
        return request.user.is_staff

class HasAPIKey(permissions.BasePermission):
    def has_permission(self, request, view):
        api_key = request.headers.get('X-API-Key')
        return api_key == settings.API_KEY
```

## Permission Classes on ViewSet

```python
class ProductViewSet(viewsets.ModelViewSet):
    permission_classes = [IsAuthenticatedOrReadOnly, IsOwnerOrReadOnly]

    def get_permissions(self):
        if self.action == 'destroy':
            return [permissions.IsAdminUser()]
        if self.action in ['create', 'update', 'partial_update']:
            return [permissions.IsAuthenticated()]
        return [permissions.AllowAny()]
```

## User Registration

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

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

    def validate(self, attrs):
        if attrs['password'] != attrs['password_confirm']:
            raise serializers.ValidationError("Passwords don't match")
        return attrs

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

class RegisterView(generics.CreateAPIView):
    serializer_class = RegisterSerializer
    permission_classes = [permissions.AllowAny]
```

## Current User Endpoint

```python
class CurrentUserView(generics.RetrieveUpdateAPIView):
    serializer_class = UserSerializer
    permission_classes = [permissions.IsAuthenticated]

    def get_object(self):
        return self.request.user
```

## Quick Reference

| Permission | Access |
|------------|--------|
| `AllowAny` | Everyone |
| `IsAuthenticated` | Logged in users |
| `IsAdminUser` | Staff users |
| `IsAuthenticatedOrReadOnly` | Auth for write |

| JWT Endpoint | Purpose |
|--------------|---------|
| `/token/` | Get access + refresh |
| `/token/refresh/` | New access from refresh |
| `/token/verify/` | Validate token |


# DRF Serializers

## ModelSerialize