Validation is never fired - django

Question

I have two models:
class Manufacturer(models.Model):
name = models.CharField(max_length = 100)
class Car(models.Model):
manufacturer = models.ForeignKey(Manufacturer, blank = True, null = True)
My serialisers:
class ManufacturerSerializer(serializers.ModelSerializer):
class Meta:
model = Manufacturer
fields = ('id', 'name')
class CarSerializer(serializers.ModelSerializer):
manufacturer = Manufact
class Meta:
model = Car
fields = ('id', 'name', 'manufacturer')
def validate(self, attrs):
try:
attrs['manufacturer'] = Manufacturer.objects.get(pk = attrs['manufacturer'])
except Manufacturer.DoesNotExist:
raise ValidationError(_('Not found'))
return attrs
My views:
class CarList(generics.ListCreateAPIView):
queryset = Car.objects.all()
serializer_class = CarSerializer
When I try to add a new Car calling POST /cars/ I get a validation error manufacturer is a required field. Car model expects manufacturer field to be Manufacturer object but to make messages small I pass it the manufacturer_id instead.
I know that should raise a ValidationError so to fix this I added a validate(..) to my CarSerializer so during validation I check if Manufacturer by this ID exists and I assign it to attrs.
Problem is this validate(..) is never called I even tried adding a post() method to CarList view and manually calling is_valid() to no success.
But I still get validation errors which I assume are coming from the Model.

Answer 1

It doesn't work because you are complicating things. The ManufacturerSerializer is not necessary (for this view anyway). By default the 'manufacturer' field will be represented as a PrimaryKeyRelatedField which will resolve your manufacturer_id to a Manufacturer object automatically, so you don't need your validate method either.
Updated serializers:
class CarPostSerializer(serializers.ModelSerializer):
class Meta:
model = Car
fields = ('id', 'name', 'manufacturer')
class CarGetSerializer(CarPostSerializer):
manufacturer = ManufacturerSerializer()
Updated view:
class CarList(generics.ListCreateAPIView):
queryset = Car.objects.all()
def get_serializer_class(self):
if self.request.method == 'POST':
return CarPostSerializer
else:
return CarGetSerializer