Polymorphic Serializer Examples per Serializer

[kalosisz]

I was wondering if it is possible to have examples per seriliazer in a polymorphic serializer schema, either by using PolymorphicProxySerializer or django-rest-polymorphic.

I have an example defined in the @extend_schema_serializer decorator, but it is not picked up.

Thanks

[tfranzel]

Hi @kalosisz

i don't think the issues lies directly with @extend_schema_serializer. I would guess this happens because examples are only retrieved from directly used serializers. By wrapping the actual serializers in PolymorphicProxySerializer or PolymorphicSerializer it would mask that annotation of the sub-serializers.

applying @extend_schema_serializer directly to a PolymorphicSerializer should work for the moment. That would mean some duplication unfortunately, since you have to likely list the examples more than once.
The end result would be the same no matter what because examples are on a endpoint level and not on a component level.

In theory this should be an easy, but I have to think about whether this would break the flow of behavior (additive or replacement).

[axieum]

I've found that applying the following decorator to any parent PolymorphicSerializer class, allows you to lift the examples up.

S = TypeVar("S", bound=PolymorphicSerializer)

def inherit_poly_serializer_examples(klass: Type[S]) -> Type[S]:
    """Applies child serializer examples to the root `PolymorphicSerializer` class."""

    set_override(
        klass,
        "examples",
        [
            example
            for child in klass.model_serializer_mapping.values()
            if hasattr(child, "_spectacular_annotation")
            for example in child._spectacular_annotation.get("examples", [])  # type: ignore
        ],
    )
    return klass

Using it like so -

@inherit_poly_serializer_examples
class MySerializer(PolymorphicSerializer):
    model_serializer_mapping = {
        MyModel: MyModelSerializer,
    }

And then, to get this to work with https://github.com/ghazi-git/drf-standardized-errors, we need to set the examples on the view rather than the serializer (since it replaces the error serializers altogether), i.e.

@extend_schema_view(
    create=extend_schema(
        examples=[*MySerializer._spectacular_annotation["examples"]],  # type: ignore
    ),
)
class MyViewSet(ModelViewSet):

[axieum]

I'd be interested to get your thoughts @tfranzel on the above, as this will tie in really nicely with the recent addition of #958 and #885. My approach above is obviously a workaround until we come up with a better way of discovering examples defined on sub-serializers.