return v.get("pet_type", "")

    Pet = Annotated[
        Union[Annotated[Cat, Tag("cat")], Annotated[Dog, Tag("dog")]],
        Discriminator(get_pet_type),
    ]

    app = FastAPI()

    @app.post("/pet/assignment")
    async def create_pet_assignment(pet: Pet = Body()):
        return pet

    @app.post("/pet/annotated")
    async def create_pet_annotated(pet: Annotated[Pet, Body()]):
        return pet

    person = Person(name="Foo")
    pet = Pet(owner=person, name="Firulais")
    assert jsonable_encoder(pet) == {"name": "Firulais", "owner": {"name": "Foo"}}
    assert jsonable_encoder(pet, include={"name"}) == {"name": "Firulais"}
    assert jsonable_encoder(pet, exclude={"owner"}) == {"name": "Firulais"}
    assert jsonable_encoder(pet, include={}) == {}
    assert jsonable_encoder(pet, exclude={}) == {
        "name": "Firulais",

@app.get("/pets/{pet_id}", response_model=PetOut)
async def read_pet(pet_id: int):
    user = UserDB(
        email="******@****.***",
        hashed_password="secrethashed",
    )
    pet = PetDB(name="Nibbler", owner=user)
    return pet


@app.get("/pets/", response_model=list[PetOut])
async def read_pets():
    user = UserDB(
        email="******@****.***",
        hashed_password="secrethashed",
    )

@app.get("/pets/{pet_id}", response_model=PetOut)
async def read_pet(pet_id: int):
    user = UserDB(
        email="******@****.***",
        hashed_password="secrethashed",
    )
    pet = PetDB(name="Nibbler", owner=user)
    return pet


@app.get("/pets/", response_model=list[PetOut])
async def read_pets():
    user = UserDB(
        email="******@****.***",
        hashed_password="secrethashed",
    )