serializer_drf.py

    def validate_data(self, data):
        ret = OrderedDict()
        errors = OrderedDict()
        fields = self._writable_fields

        for field in fields:
            validate_method = getattr(
                self, 'validate_' + field.field_name, None)
            primitive_value = field.get_value(data)
            try:
                validated_value = field.run_validation(primitive_value)
                if validate_method is not None:
                    validated_value = validate_method(validated_value)
            except ValidationError as exc:
                errors[field.field_name] = exc.detail
            except DjangoValidationError as exc:
                errors[field.field_name] = get_error_detail(exc)
            except SkipField:
                pass
            else:
                set_value(ret, field.source_attrs, validated_value)

        if errors:
            errors['id'] = data['id']
            raise ValidationError(errors)

        return ret