### Create an `Enum` class

Import `Enum` and create a sub-class that inherits from `str` and from `Enum`.

By inheriting from `str` the API docs will be able to know that the values must be of type `string` and will be able to render correctly.

Then create class attributes with fixed values, which will be the available valid values:

```Python hl_lines="1  6-9"
{!../../../docs_src/path_params/tutorial005.py!}
```

!!! info

**Spoiler-Alarm**: Das Tutorial - Benutzerhandbuch enthält:

* Deklaration von **Parametern** von anderen verschiedenen Stellen wie: **Header-Felder**, **Cookies**, **Formularfelder** und **Dateien**.
* Wie man **Validierungseinschränkungen** wie `maximum_length` oder `regex` setzt.

# Header 参数

定义 `Header` 参数的方式与定义 `Query`、`Path`、`Cookie` 参数相同。

## 导入 `Header`

首先，导入 `Header`：

=== "Python 3.10+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/header_params/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/header_params/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="3"

# Header-параметры

Вы можете определить параметры заголовка таким же образом, как вы определяете параметры `Query`, `Path` и `Cookie`.

## Импорт `Header`

Сперва импортируйте `Header`:

=== "Python 3.10+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/header_params/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/header_params/tutorial001_an_py39.py!}
    ```

## `Header` 임포트

먼저 `Header`를 임포트합니다:

```Python hl_lines="3"
{!../../../docs_src/header_params/tutorial001.py!}
```

## `Header` 매개변수 선언

`Path`, `Query` 그리고 `Cookie`를 사용한 동일한 구조를 이용하여 헤더 매개변수를 선언합니다.

첫 번째 값은 기본값이며, 추가 검증이나 어노테이션 매개변수 모두 전달할 수 있습니다:

```Python hl_lines="9"
{!../../../docs_src/header_params/tutorial001.py!}
```

!!! note "기술 세부사항"

import functools

import pytest
from fastapi import (
    APIRouter,
    Depends,
    FastAPI,
    Header,
    WebSocket,
    WebSocketDisconnect,
    status,
)
from fastapi.middleware import Middleware
from fastapi.testclient import TestClient

router = APIRouter()
prefix_router = APIRouter()
native_prefix_route = APIRouter(prefix="/native")
app = FastAPI()


@app.websocket_route("/")

def test_header_repr_str():
    assert repr(Header("teststr")) == "Header(teststr)"


def test_header_repr_none():
    assert repr(Header(None)) == "Header(None)"


def test_header_repr_ellipsis():
    assert repr(Header(...)) == IsOneOf(
        "Header(PydanticUndefined)",
        # TODO: remove when deprecating Pydantic v1
        "Header(Ellipsis)",
    )

@pytest.fixture(name="client")
def get_client():
    from docs_src.header_params.tutorial002_an_py310 import app

    client = TestClient(app)
    return client


@needs_py310
@pytest.mark.parametrize(
    "path,headers,expected_status,expected_response",
    [
        ("/items", None, 200, {"strange_header": None}),
        ("/items", {"X-Header": "notvalid"}, 200, {"strange_header": None}),
        (
            "/items",

from docs_src.handling_errors.tutorial002 import app

client = TestClient(app)


def test_get_item_header():
    response = client.get("/items-header/foo")
    assert response.status_code == 200, response.text
    assert response.json() == {"item": "The Foo Wrestlers"}


def test_get_item_not_found_header():
    response = client.get("/items-header/bar")
    assert response.status_code == 404, response.text

from typing import Annotated

from fastapi import FastAPI, Header

app = FastAPI()


@app.get("/items/")
async def read_items(
    strange_header: Annotated[str | None, Header(convert_underscores=False)] = None,
):