from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: Optional[str] = None


class OtherItem(BaseModel):
    price: int


@app.post("/items/")
def save_union_body(item: Union[OtherItem, Item]):
    return {"item": item}


client = TestClient(app)


def test_post_other_item():
    response = client.post("/items/", json={"price": 100})

    app = FastAPI()

    class FirstItem(BaseModel):
        value: Literal["first"]
        price: int

    class OtherItem(BaseModel):
        value: Literal["other"]
        price: float

    Item = Annotated[
        Union[Annotated[FirstItem, Tag("first")], Annotated[OtherItem, Tag("other")]],
        Field(discriminator="value"),
    ]

    @app.post("/items/")
    def save_union_body_discriminator(