          # TODO: filter queryset using:
          # .using(db).complex_filter(self.rel.limit_choices_to)
          queryset = model_field.rel.to._default_manager
          if to_many:
              return ManyPrimaryKeyRelatedField(queryset=queryset)
          return PrimaryKeyRelatedField(queryset=queryset)
  
      def get_field(self, model_field):
          """
          Creates a default instance of a basic non-relational field.
          """
 
</s> remove         queryset = rel._default_manager
 </s> add  </s> remove         into[(self.source or field_name)] = self.from_native(value)
 </s> add         if value is None and not self.blank:
            raise ValidationError('Value may not be null')
        elif value is None and self.blank:
            into[(self.source or field_name)] = None
        else:
            into[(self.source or field_name)] = self.from_native(value) </s> remove         response = self.detail_view(request, pk=1).render()
 </s> add         response = self.detail_view(request, pk=1) </s> remove         # # Ensure source 1 is updated, and everything else is as expected
 </s> add         # Ensure source 1 is updated, and everything else is as expected
            return ManyPrimaryKeyRelatedField(**kwargs)
        return PrimaryKeyRelatedField(**kwargs)
          # TODO: filter queryset using:
          # .using(db).complex_filter(self.rel.limit_choices_to)
          queryset = model_field.rel.to._default_manager
          if to_many:
            return ManyPrimaryKeyRelatedField(**kwargs)
        return PrimaryKeyRelatedField(**kwargs)
            return ManyPrimaryKeyRelatedField(**kwargs)
        return PrimaryKeyRelatedField(**kwargs)
  
      def get_field(self, model_field):
          """
          Creates a default instance of a basic non-relational field.
          """
keep keep keep keep replace replace keep keep keep keep keep
 Support nullable FKs, with blank=True 
rest_framework/serializers.py