**FastAPI** позволяет определять дополнительную информацию и выполнять валидацию для ваших параметров.

Рассмотрим это приложение в качестве примера:

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

Query-параметр `q` имеет тип `str | None`, это означает, что он имеет тип `str`, но также может быть `None`. Значение по умолчанию действительно `None`, поэтому FastAPI будет знать, что он не обязателен.

from inline_snapshot import snapshot

from tests.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.dataclasses_.{request.param}")

    client = TestClient(mod.app)

import pytest
from fastapi.testclient import TestClient

from ...utils import needs_py310


@pytest.fixture(
    name="client",
    params=[
        "tutorial001_py39",
        pytest.param("tutorial001_py310", marks=needs_py310),
        "tutorial001_an_py39",
        pytest.param("tutorial001_an_py310", marks=needs_py310),
    ],
)
def get_client(request: pytest.FixtureRequest):

import pytest
from fastapi.testclient import TestClient

from ...utils import needs_py310


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial001_py39"),
        pytest.param("tutorial001_py310", marks=needs_py310),
        pytest.param("tutorial001_an_py39"),
        pytest.param("tutorial001_an_py310", marks=needs_py310),
        pytest.param("tutorial001_02_an_py39"),

{* ../../docs_src/custom_request_and_route/tutorial003_py310.py hl[26] *}

In diesem Beispiel verwenden die *Pfadoperationen* unter dem `router` die benutzerdefinierte `TimedRoute`-Klasse und haben in der Response einen zusätzlichen `X-Response-Time`-Header mit der Zeit, die zum Generieren der Response benötigt wurde:

You can use `jsonable_encoder` for that.

It receives an object, like a Pydantic model, and returns a JSON compatible version:

{* ../../docs_src/encoder/tutorial001_py310.py hl[4,21] *}

In this example, it would convert the Pydantic model to a `dict`, and the `datetime` to a `str`.

import pytest
from fastapi.testclient import TestClient

from ...utils import needs_py310


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial001_py39"),
        pytest.param("tutorial001_py310", marks=needs_py310),
        pytest.param("tutorial001_an_py39"),
        pytest.param("tutorial001_an_py310", marks=needs_py310),
    ],
)
def get_client(request: pytest.FixtureRequest) -> TestClient:

import pytest
from fastapi.testclient import TestClient

from ...utils import needs_py310


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial001_py39"),
        pytest.param("tutorial001_py310", marks=needs_py310),
    ],
)
def get_client(request: pytest.FixtureRequest) -> TestClient:
    mod = importlib.import_module(f"docs_src.separate_openapi_schemas.{request.param}")

    client = TestClient(mod.app)

from fastapi.testclient import TestClient

from tests.utils import needs_py310


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial001_py39"),
        pytest.param("tutorial001_py310", marks=needs_py310),
        pytest.param("tutorial001_an_py39"),
        pytest.param("tutorial001_an_py310", marks=needs_py310),
    ],
)
def get_client(request: pytest.FixtureRequest):

Você pode usar a função `jsonable_encoder` para resolver isso.

A função recebe um objeto, como um modelo Pydantic e retorna uma versão compatível com JSON:

{* ../../docs_src/encoder/tutorial001_py310.py hl[4,21] *}

Neste exemplo, ele converteria o modelo Pydantic em um `dict`, e o `datetime` em um `str`.