I think it's not a secret for anyone that in conversations of experienced Python developers, and not only, phrases often slip that Django is evil, that Django has a bad architecture and it is impossible to write a large project on it without pain. Even a medium Django project is often difficult to maintain and extend. I propose to figure out why this is happening and what is wrong with Django projects.
A bit of theory
When we start learning Django without experience from other languages and frameworks, in addition to documentation, we read tutorials, articles, books, and in almost all we see something like this:
Django is a framework that uses the Model-View-Controller (MVC) design pattern.
And then a bunch of inaccurate diagrams and explanations about what MVC is. Why they are inaccurate and what is wrong with them, you can see here or here .
Typically, such schemes describe MVC in this way:
Model - access to the data store
View is the interface with which the user interacts
Controller is a kind of connecting object between model and view.
These common schemes only confuse and get in the way when you want to write an application that contains business logic.
There are two things worth noticing.
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class CommentSerializer(serializers.Serializer):
email = serializers.EmailField()
content = serializers.CharField(max_length=200)
created = serializers.DateTimeField()
def create(self, validated_data):
return Comment.objects.create(**validated_data)
def update(self, instance, validated_data):
instance.email = validated_data.get('email', instance.email)
instance.content = validated_data.get('content', instance.content)
instance.created = validated_data.get('created', instance.created)
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# serializers.py
class OrderSerializer(serializers.ModelSerializer):
class Meta:
model = Order
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# views.py
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queryset = Order.objects.all()
serializer_class = OrderSerializer
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model = Order
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class OrderViewsSet(viewsets.ModelViewSet):
queryset = Order.objects.all()
serializer_class = OrderSerializer
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class OrderViewsSet(viewsets.ModelViewSet):
queryset = Order.objects.all()
serializer_class = OrderSerializer
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# views.py
class OrderCreateApi(views.APIView):
class InputSerializer(serializers.ModelSerializer):
number = serializers.IntegerField()
...
def post(self, request):
serializer = self.InputSerializer(data=request.data)
serializer.is_valid(raise_exception=True)
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# views.py
class OrderViewsSet(viewsets.ModelViewSet):
queryset = Order.objects.all()
serializer_class = OrderSerializer
def get_queryset(self):
queryset = super(OrderViewsSet, self).get_queryset()
queryset = queryset.filter(user=self.request.user)
return queryset
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# models.py
class Order(models.Model):
number = serializers.IntegerField()
created = models.DateTimeField(auto_now_add=True)
status = models.CharField(max_length=16)
def update_status(self, status: str) -> None:
self.status = status
self.save(update_fields=('status',))
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class OrderCreateApi(views.APIView):
class InputSerializer(serializers.ModelSerializer):
number = serializers.IntegerField()
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def post(self, request):
serializer = self.InputSerializer(data=request.data)
serializer.is_valid(raise_exception=True)
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# views.py
class OrderListApi(views.APIView):
class OutputSerializer(serializers.ModelSerializer):
class Meta:
model = Order
fields = ‘__all__’
def get(self, request):
orders = Order.objects.filter(user=request.user)
#
# , Order.objects.filter(user=request.user, is_deleted=False, is_archived=False...)
# Manager
data = self.OutputSerializer(orders, many=True).data
return Response(data)
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# models.py
class Order(models.Model):
number = serializers.IntegerField()
created = models.DateTimeField(auto_now_add=True)
status = models.CharField(max_length=16)
def update_status(self, status: str) -> None:
self.status = status
self.save(update_fields=('status',))
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# DTO
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order = Order.objects.create(...)
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# views.py
class OrderCreateApi(views.APIView):
class InputSerializer(serializers.ModelSerializer):
number = serializers.IntegerField()
...
def post(self, request):
serializer = self.InputSerializer(data=request.data)
serializer.is_valid(raise_exception=True)
services.order_create(**serializer.validated_data)
return Response(status=status.HTTP_201_CREATED)
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# services.py
def order_get_by_user(user: User) -> Iterable[Order]:
return Order.objects.filter(user=user)
# views.py
class OrderListApi(views.APIView):
class OutputSerializer(serializers.ModelSerializer):
class Meta:
model = Order
fields = ('id', 'number', ...)
def get(self, request):
orders = services.order_get_by_user(user=request.user)
data = self.OutputSerializer(orders, many=True).data
return Response(data)
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