**FastAPI** te permite declarar información adicional y validación para tus parámetros.

Tomemos esta aplicación como ejemplo:

{* ../../docs_src/query_params_str_validations/tutorial001_py310.py hl[7] *}

El parámetro de query `q` es de tipo `str | None`, lo que significa que es de tipo `str` pero también podría ser `None`, y de hecho, el valor por defecto es `None`, así que FastAPI sabrá que no es requerido.

from inline_snapshot import snapshot

from tests.utils import needs_py310


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial003_py39"),
        pytest.param("tutorial003_py310", marks=needs_py310),
        pytest.param("tutorial003_an_py39"),
        pytest.param("tutorial003_an_py310", marks=needs_py310),
    ],
)
def get_client(request: pytest.FixtureRequest):

from fastapi.websockets import WebSocketDisconnect

from ...utils import needs_py310


@pytest.fixture(
    name="app",
    params=[
        pytest.param("tutorial002_py39"),
        pytest.param("tutorial002_py310", marks=needs_py310),
        pytest.param("tutorial002_an_py39"),
        pytest.param("tutorial002_an_py310", marks=needs_py310),
    ],
)
def get_app(request: pytest.FixtureRequest):

import pytest
from fastapi.testclient import TestClient

from ...utils import needs_py310


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial002_py39"),
        pytest.param("tutorial002_py310", marks=needs_py310),
    ],
)
def get_client(request: pytest.FixtureRequest):
    mod = importlib.import_module(f"docs_src.body_multiple_params.{request.param}")

    client = TestClient(mod.app)

from fastapi.testclient import TestClient

from ...utils import needs_py310


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial005_py39"),
        pytest.param("tutorial005_py310", marks=needs_py310),
    ],
)
def get_client(request: pytest.FixtureRequest):
    mod = importlib.import_module(f"docs_src.body_nested_models.{request.param}")

    client = TestClient(mod.app)
    return client

    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2
}
```

But you can also declare multiple body parameters, e.g. `item` and `user`:

{* ../../docs_src/body_multiple_params/tutorial002_py310.py hl[20] *}


In this case, **FastAPI** will notice that there is more than one body parameter in the function (there are two parameters that are Pydantic models).

    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2
}
```

Aber Sie können auch mehrere Body-Parameter deklarieren, z. B. `item` und `user`:

{* ../../docs_src/body_multiple_params/tutorial002_py310.py hl[20] *}

In diesem Fall wird **FastAPI** bemerken, dass es mehr als einen Body-Parameter in der Funktion gibt (zwei Parameter, die Pydantic-Modelle sind).

{* ../../docs_src/background_tasks/tutorial002_an.py hl[14, 16, 23, 26] *}

////

//// tab | Python 3.10+ 没Annotated

/// tip

尽可能选择使用 `Annotated` 的版本。

///

{* ../../docs_src/background_tasks/tutorial002_py310.py hl[11, 13, 20, 23] *}

////

//// tab | Python 3.8+ 没Annotated

/// tip

尽可能选择使用 `Annotated` 的版本。

///

{* ../../docs_src/background_tasks/tutorial002.py hl[13, 15, 22, 25] *}

////

    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2
}
```

Но вы также можете объявить множество параметров тела запроса, например `item` и `user`:

{* ../../docs_src/body_multiple_params/tutorial002_py310.py hl[20] *}

В этом случае **FastAPI** заметит, что в функции есть более одного параметра тела (два параметра, которые являются Pydantic-моделями).

For those cases, you can use the `jsonable_encoder` to convert your data before passing it to a response:

{* ../../docs_src/response_directly/tutorial001_py310.py hl[5:6,20:21] *}

/// note | Technical Details

You could also use `from starlette.responses import JSONResponse`.