///

**FastAPI** はすべてPydanticをベースにしています。

すべてのことは[チュートリアル - ユーザーガイド](tutorial/index.md){.internal-link target=_blank}で実際に見ることができます。

## **FastAPI**での型ヒント

**FastAPI** はこれらの型ヒントを利用していくつかのことを行います。

**FastAPI** では型ヒントを使って型パラメータを宣言すると以下のものが得られます:

* **エディタサポート**.
* **型チェック**.

...そして **FastAPI** は同じように宣言をすると、以下のことを行います:

Por exemplo, se você quiser ler ou manipular o corpo da requisição antes que ele seja processado pela sua aplicação.

/// danger | Cuidado

Isso é um recurso "avançado".

Se você for um iniciante em **FastAPI** você deve considerar pular essa seção.

///

## Casos de Uso { #use-cases }

Alguns casos de uso incluem:

import inspect
import sys
from dataclasses import dataclass, field
from functools import cached_property, partial
from typing import Any, Callable, Optional, Union

from fastapi._compat import ModelField
from fastapi.security.base import SecurityBase
from fastapi.types import DependencyCacheKey
from typing_extensions import Literal

if sys.version_info >= (3, 13):  # pragma: no cover
    from inspect import iscoroutinefunction

from fastapi import FastAPI, Header, HTTPException
from pydantic import BaseModel

fake_secret_token = "coneofsilence"

fake_db = {
    "foo": {"id": "foo", "title": "Foo", "description": "There goes my hero"},
    "bar": {"id": "bar", "title": "Bar", "description": "The bartenders"},
}

app = FastAPI()


class Item(BaseModel):
    id: str
    title: str
    description: str | None = None

from typing import Union

from fastapi import FastAPI, Header, HTTPException
from pydantic import BaseModel

fake_secret_token = "coneofsilence"

fake_db = {
    "foo": {"id": "foo", "title": "Foo", "description": "There goes my hero"},
    "bar": {"id": "bar", "title": "Bar", "description": "The bartenders"},
}

app = FastAPI()


class Item(BaseModel):
    id: str
    title: str
    description: Union[str, None] = None

Importieren Sie es zuerst:

{* ../../docs_src/body_fields/tutorial001_an_py310.py hl[4] *}

/// warning | Achtung

Beachten Sie, dass `Field` direkt von `pydantic` importiert wird, nicht von `fastapi`, wie die anderen (`Query`, `Path`, `Body`, usw.)

///

## Modellattribute deklarieren { #declare-model-attributes }

Dann können Sie `Field` mit Modellattributen deklarieren:

from fastapi.testclient import TestClient

from docs_src.generate_clients.tutorial003_py39 import app

client = TestClient(app)


def test_post_items():
    response = client.post("/items/", json={"name": "Foo", "price": 5})
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Item received"}


def test_post_users():
    response = client.post(

import importlib

import pytest
from dirty_equals import IsList
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) -> TestClient:
    mod = importlib.import_module(

import importlib
from typing import Union

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.{request.param}")

```console
// Не запускайте это сейчас, это просто пример 🤓
$ pip install "fastapi[standard]"
---> 100%
```

</div>

Будет загружен сжатый файл с кодом FastAPI, обычно с <a href="https://pypi.org/project/fastapi/" class="external-link" target="_blank">PyPI</a>.

Также будут **загружены** файлы для других пакетов, от которых зависит FastAPI.