Workaround for #150 FastAPI shows no attributes for models.

[markus-work]

What I am changing

• This is a temporary workaround until FastAPI shows no attributes for models when a @model_serializer is used. fastapi/fastapi#10661 is answered in a better way. I am just making this available here in case someone else would like to use it. I can finalise it better(changelog and such) if this is something that wants to be merged into main.

How I did it

• Changing the typehinting according to workaround mention here to get the model to show up in fast api swagger docs.

How you can test it

• See FastAPI shows no attributes for models. #150 for a simple case.

Related Issues

• FastAPI shows no attributes for models. #150

[vincentsarago]

@markus-work what happens if we use Dict or Dict[Any, Any] instead of Any

TBH, I'm not quite sure of all the implication of this change (cc @eseglem)

I would also add a comment in the code directly about this change/issue

[eseglem]

I have been digging through this for a bit to get to the core of it, and it has something to do with how pydantic schema generation interacts with the @model_serializer. Essentially, FastAPI will call .model_json_schema(mode="serialization") and then pydantic will use the return type of the serializer function.

Unfortunately, it does not look like -> Any fixes the issue. At least not in my testing. Adjusting return type only works either having no return type at all, or pydantic_core.PydanticUndefined. Neither of which are ideal.

I don't particularly like it, but the cleanest solution appears to be:

    def clean_model(self, serializer: Any, info: SerializationInfo):  # type: ignore [no-untyped-def]

Simple test, which could be parametrized for all the types:

from geojson_pydantic import Point

def test_schema():
    assert Point.model_json_schema(mode="validation") == Point.model_json_schema(
        mode="serialization"
    )

I tried to work a solution with __get_pydantic_core_schema__ and it worked in a simple test, but ended up with a RecursionError when trying to implement it _GeoJsonBase. And I think it may be related to generics. Might be fixable in there somewhere, but not going to be pretty. I may try and put something together as an issue on Pydantic and see what they say, as well.

[markus-work]

You're right, Any does not work. Should I change it to # type: ignore [no-untyped-def] for now?

[eseglem]

Seems like the best solution for the time being. Think its worth adding any tests @vincentsarago ?

[markus-work]

I added the test you suggested. I added the type hinting back locally to see if the test failed, and it did. So the test is valid for this problem.

[markus-work]

Should I update the changelog and run bump2version as well?

[vincentsarago]

@markus-work I'll take care of the changelog 🙏

thank for the all the good work

[Kusmeroglu]

Just popping in here to say thank you! I just ran into this problem and ya'll just fixed it! <3

[eseglem]

Thanks for chiming in @Kusmeroglu. It reminded me I still wanted to write up an issue on pydantic: pydantic/pydantic#8791

If anyone wants to thumbs up it, or chime in, could help with getting a nicer (less hacky) solution.