async def read_optional_str(p: Annotated[Optional[str], Form()] = None):
    return {"p": p}


class FormModelOptionalStr(BaseModel):
    p: Optional[str] = None


@app.post("/model-optional-str", operation_id="model_optional_str")
async def read_model_optional_str(p: Annotated[FormModelOptionalStr, Form()]):
    return {"p": p.p}


@pytest.mark.parametrize(
    "path",
    ["/optional-str", "/model-optional-str"],
)

    return {"p": p}


class BodyModelOptionalStr(BaseModel):
    p: Optional[str] = None


@app.post("/model-optional-str", operation_id="model_optional_str")
async def read_model_optional_str(p: BodyModelOptionalStr):
    return {"p": p.p}


@pytest.mark.parametrize(
    "path",
    ["/optional-str", "/model-optional-str"],
)