Django Rest Framework - Post Foreign Key

Question

I am new to Django Rest Framework and checked some tutorials. Now I am trying to create my own structure which is like following. I want to create a user which is OK, then create a profile seperately.

models.py

class User(models.Model):

  name = models.CharField(max_length=32)
  surname = models.CharField(max_length=32)
  facebook_id = models.TextField(null=True)
  is_sms_verified = models.BooleanField(default=False)
  created = models.DateTimeField(default=timezone.now)
  updated = models.DateTimeField(default=timezone.now)
  status = models.BooleanField(default=1)

 def __str__(self):
  return self.name+" "+self.surname

class Profile(models.Model):

  user = models.ForeignKey('User',on_delete=models.CASCADE)
  email = models.CharField(max_length=32)
  birthday = models.DateField(null=True)
  bio = models.TextField(null=True)
  points = models.IntegerField(default=0)
  created = models.DateTimeField(default=timezone.now)
  updated = models.DateTimeField(default=timezone.now)

  def __str__(self):
   return self.user.name+ " " + self.user.surname

serializers.py

class UserSerializer(serializers.ModelSerializer):

  class Meta:
    model=User
    fields = ('id','name','surname','facebook_id','is_sms_verified',)
    read_only_fields = ('created','updated')

class ProfileSerializer(serializers.ModelSerializer):
  user = UserSerializer(read_only=True)

  class Meta:
    model=Profile
    fields=('id','user','email','birthday','bio','points')
    read_only_fields = ('created','updated')

views.py

@api_view(['POST'])
def profile_create(request):
  serializer = ProfileSerializer(data=request.data)
  if serializer.is_valid():
    serializer.save()
    return JsonResponse(serializer.data, status = status.HTTP_201_CREATED)
  return JsonResponse(serializer.errors , status= status.HTTP_400_BAD_REQUEST)

data I'm trying to post

{
  "user_id": {
      "id": 2
   },
  "email": "[email protected]",
  "birthday": "1991-05-28",
  "bio": "qudur",
  "points": 31
}

The error I get;

NOT NULL constraint failed: core_profile.user_id

Where am I doing wrong? Thanks!

Answer 1

Your ProfileSerializer has user as readonly. So you need to change that. I would suggest doing it like this

class ProfileSerializer(serializers.ModelSerializer):
    class Meta:
        model=Profile
        fields=('id','user','email','birthday','gender','bio','points')
        read_only_fields = ('created','updated')

    def to_representation(self, instance):
        self.fields['user'] =  UserSerializer(read_only=True)
        return super(ProfileSerializer, self).to_representation(instance)

If you do it this you could provide your user as plain id for POST

{
  "user": 2,
  "email": "[email protected]",
  "birthday": "1991-05-28",
  "bio": "qudur",
  "points": 31
}

And when you will read data it will look like this

{
  "user": {
    "id": 2,
    "name": "Name",
    "surname": "Surname",
    ...
  },
  "email": "[email protected]",
  "birthday": "1991-05-28",
  "bio": "qudur",
  "points": 31
}

Answer 2

I've noticed Super() throws an error the way it's mentioned above in the awnser:

return super(ProfileSerializer,self).to_representation(instance)

Error: Type error, object must be an instance or subtype of type

Try the Following:

Models.py

class Program(models.Model):
    name = models.CharField(max_length=225)
    cost = models.IntegerField(default=0)
    description = models.TextField(default="", max_length=555)

class UserProgram(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    program = models.ForeignKey(Program, on_delete=models.CASCADE, related_name="program")

Serializers.py

class ProgramSerializers(serializers.ModelSerializer):
    class Meta:
        model = Program
        fields = "__all__"

class UserProgramSerializers(serializers.ModelSerializer):
    class Meta:
        model = UserProgram
        fields = "__all__"

    #IMPORTANT PART
    def to_representation(self, instance):
        response = super().to_representation(instance)
        response['program'] = ProgramSerializers(instance.program).data
        return response

Views.py

class UserProgramViewset(viewsets.ModelViewSet):
     permission_classes = [
        permissions.IsAuthenticated
     ]
     serializer_class = UserProgramSerializers
     
     def get_queryset(self):
        return UserProgram.objects.filter(user=self.request.user)    

     def perform_create(self, serializer):
        serializer.save(user=self.request.user)

When you call the GET request the following should be the output: GET Request Output

When you call the POST request you only need to pass the programID and not the whole JSON dictionary!

Hope this helped.