201 Created - but no new object in SqLite database

Question

Edit 25th Jan: here's my model!

class rat(models.Model):
    name = models.CharField(max_length=132, null =True)
    body_colour = models.ForeignKey(BodyColour, on_delete=models.CASCADE, null = True, related_name='body_colour')
    eye_colour = models.ForeignKey(EyeColour, on_delete=models.CASCADE, null = True, related_name='eye_colour')
    user = models.ForeignKey(User, on_delete=models.CASCADE, null = True)

    bio = models.TextField(null = True, blank = True)
    born = models.DateField(auto_now_add=True)
    image = models.ForeignKey(Image, on_delete=models.CASCADE, null = True, blank=True)

Adding rat.save() to the serializer gives me the following error: TypeError: int() argument must be a string, a bytes-like object or a real number, not 'dict'

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I have a button that users can click on to add an object to their account. It's sent through django to my sqlite db, and in the console log there are no errors. It says "201 Created", and yet there is no new object in the database.

Someone else had the same problem as me, the solution was getting rid of some methods in the serializer, but they don't specify what they got rid off.

What's causing this?

Here is my serializer:

class RatSerializer(FlexFieldsModelSerializer, serializers.ModelSerializer):
    name         = serializers.CharField()
    user         = serializers.CharField(source='user.username', required=False)
    userid       = serializers.CharField(source='user.id', required=False)
    body_colour  = BodyColourSerializer()
    eye_colour   = EyeColourSerializer()
    image        = ImageSerializer(required=False)


    class Meta:
        model = rat
        exclude = ['bio']

    def create(self, data):
        request = self.context.get("request")
        user = request.user

        return rat( name = data["name"],
            body_colour = BodyColour(name=data["body_colour"]["name"]),
            eye_colour = EyeColour(name=data["eye_colour"]["name"]),
            image = Image(),
            user = user)

My views:

class ratViewset(ModelViewSet, APIView):
    serializer_class = RatSerializer
    # queryset = rat.objects.all()
    
    def get_queryset(self):
        user = self.request.user
        if user.is_anonymous:
            return rat.objects.all()
        return rat.objects.filter(user=user.id)
        
    def post(self, request):
            rat = request.data.get('rat')
            # creates rat with the above data
            serializer = RatSerializer(data=rat)
            
            if serializer.is_valid(raise_exception=True):
                serializer.save()
                print(serializer.data, type(serializer.data))
                return Response(serializer.data, status=status.HTTP_201_CREATED)
            return Response(serializer.errors, status=status)

Grateful for any help!