How to properly create a oneof in Python?

[ottmar-zittlau]

Hi,

I have some issues creating a oneof in Python.

I'd like to implement a oneof with three options:

get:
  operationId: doSomething
  x-bidistream: true
  requestBody:
    content:
      application/json:
        schema:
          oneOf:
            - $ref: '../components/schemas/Option1.yaml'
            - $ref: '../components/schemas/Option2.yaml'
            - $ref: '../components/schemas/Option3.yaml'

The generator correctly generates a request for this comprising all these options:

class doSomethingRequest(BaseModel):
    oneof_schema_1_validator: Optional[Option1] = None
    oneof_schema_2_validator: Optional[Option2] = None
    oneof_schema_3_validator: Optional[Option3] = None

The websocket endpoint looks like this:

async def do_something(self, client_request_generator: Callable[[AsyncGenerator[DoSomethingResponse, None]], AsyncGenerator[DoSomethingRequest, None]]) -> None:  # noqa: E501

My async generator looks like this:

 async def faulty_request_generator(
            response_generator: AsyncGenerator[Models.DoSomethingResponse, None],
            request: Union[Models.Option1, Models.Option2, Models.Option3],
        ) -> AsyncGenerator[Models.DoSomethingRequest, None]:

            yield Models.DoSomethingRequest(request)

This doesn't seem to work, because if I wrap my request in Models.DoSomethingRequest in the yield command, the json that is sent seems to ignore the oneof-character of this message. Somewhere pydantics model_dump_json is called on this message which will also include oneof_schema_1_validator etc.

If I just call yield request, everything works, but MyPy complains that the types don't match. I could disable this warning, but somehow it feels wrong.

I noticed that there is a to_json method of the DoSomethingRequest-class, which seems to do the correct thing, but it doesn't seem to get called. Do I have to setup something to make this work?

Thanks and best regards
oz