Django - 使用外键对象创建模型对象

Question

I don't feel like I get an idea on how it should work...

I do have 2 models:
Group is my custom model I wanna save.

class Group(models.Model):
    name = models.CharField(max_length=40)
    subject = models.CharField(max_length=40)

    user = models.ForeignKey('User', on_delete=models.CASCADE)

User is a standard user model for the application. I'm skipping UserManager for now. Simply said User can have multiple groups.

class User(AbstractBaseUser, PermissionsMixin):
    name = models.CharField(max_length=40, null=True, blank=True)
    surname = models.CharField(max_length=40, null=True, blank=True)
    objects = UserManager()

A serializer for the custom model:

class GroupSerializer(serializers.ModelSerializer):
    class Meta:
        model = Group
        fields = ('id', 'name', 'subject', 'user')

And a viewset with overwritten create method:

class GroupViewSet(viewsets.ModelViewSet):
    serializer_class = GroupSerializer

    def create(self, request, *args, **kwargs):
        group = group.objects.create(user=self.request.user)
        serializer = GroupSerializer(group)

        return Response(serializer.data)

When calling a POST a new Group is created. The Group has relation to the User , but other fields (name, subject) are empty.

On the other hand, when doing the request serialization, the User on the object is empty.

    def create(self, request, *args, **kwargs):
        serializer = GroupSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)

        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

How do I connect those 2 to make it work?

Answer 1

That makes sense since you never used the serializer to deserialize the request, and thus read the details passed in the POST request. You can work with:

def create(self, request, *args, **kwargs):
    serializer = 
    if serializer.is_valid():
        serializer.save()
    else:
        # return response when the serializer rejects the input
        pass
    # return a response
    pass

In the serializer you mark the user field as read_only , to prevent the serializer from failing in case the user was not part of the request:

class GroupSerializer(serializers.ModelSerializer):
    class Meta:
        model = Group
        fields = ('id', 'name', 'subject', 'user')