django-rest-framework edit data after validation

Question

I have a few fields on my serializer and I have overridden the validate method on serializer to do some object-level validation.

The problem is after validation, I need to edit the final data before passing it to create function. Currently, I'm doing this:

class MySerializer(serializers.ModelSerializer):

    def validate(self, attrs):
        # Some lengthy validation with attrs['a'] and attrs['b'] and attrs['c']

        # if validated
        attrs['a'] = updated_a
        attrs['b'] = updated_b
        attrs['c'] = updated_c
        return attrs

Update has to be done after the validation. I was wondering if there is a better way to handle this.

I could subclass the Field and provide custom to_internal and to_representation but I don't know how to do validation beforehand.

Answer 1

validate method is not the best place for this. Especially when now in DRF3 you have create method available for you.

def create(self, validated_data):
    data = validated_data.copy()
    data['a'] = 'updated value'
    return super(MySerializer, self).create(**data)