Also fügen wir sie in ihr eigenes `dependencies`-Modul (`app/dependencies.py`) ein.

Wir werden nun eine einfache Abhängigkeit verwenden, um einen benutzerdefinierten `X-Token`-Header zu lesen:

{* ../../docs_src/bigger_applications/app_an_py39/dependencies.py hl[3,6:8] title["app/dependencies.py"] *}

/// tip | Tipp

Мы поместим их в отдельный модуль `dependencies` (`app/dependencies.py`).

Теперь мы воспользуемся простой зависимостью, чтобы прочитать кастомизированный `X-Token` из заголовка:

{* ../../docs_src/bigger_applications/app_an_py39/dependencies.py hl[3,6:8] title["app/dependencies.py"] *}

/// tip | Подсказка

Для простоты мы воспользовались неким воображаемым заголовоком.

    discussion_id: Union[str, None] = None,
    comment_id: Union[str, None] = None,
    body: Union[str, None] = None,
) -> dict[str, Any]:
    headers = {"Authorization": f"token {settings.github_token.get_secret_value()}"}
    variables = {
        "after": after,
        "category_id": category_id,
        "discussion_number": discussion_number,
        "discussion_id": discussion_id,

### 拡張版 **FastAPI** アプリファイル

**FastAPI** アプリに `main_b.py` ファイルがあるとします。

そのファイルには、エラーを返す可能性のある `GET` オペレーションがあります。

また、いくつかのエラーを返す可能性のある `POST` オペレーションもあります。

これらの *path operation* には `X-Token` ヘッダーが必要です。

{* ../../docs_src/app_testing/app_b_py310/main.py *}

### 拡張版テストファイル

次に、先程のものに拡張版のテストを加えた、`test_main_b.py` を作成します。

{* ../../docs_src/app_testing/app_b/test_main.py *}

	AmzExpires              = "X-Amz-Expires"
	AmzSignedHeaders        = "X-Amz-SignedHeaders"
	AmzSignature            = "X-Amz-Signature"
	AmzCredential           = "X-Amz-Credential"
	AmzSecurityToken        = "X-Amz-Security-Token"
	AmzDecodedContentLength = "X-Amz-Decoded-Content-Length"
	AmzTrailer              = "X-Amz-Trailer"
	AmzMaxParts             = "X-Amz-Max-Parts"
	AmzPartNumberMarker     = "X-Amz-Part-Number-Marker"

...
```

#### What is OpenAPI for { #what-is-openapi-for }

The OpenAPI schema is what powers the two interactive documentation systems included.

And there are dozens of alternatives, all based on OpenAPI. You could easily add any of those alternatives to your application built with **FastAPI**.

pkg go/build, type Directive struct #56986
pkg go/build, type Directive struct, Pos token.Position #56986
pkg go/build, type Directive struct, Text string #56986
pkg go/build, type Package struct, Directives []Directive #56986
pkg go/build, type Package struct, TestDirectives []Directive #56986
pkg go/build, type Package struct, XTestDirectives []Directive #56986
pkg go/token, method (*File) Lines() []int #57708

We see that we are going to need some dependencies used in several places of the application.

So we put them in their own `dependencies` module (`app/dependencies.py`).

We will now use a simple dependency to read a custom `X-Token` header:

{* ../../docs_src/bigger_applications/app_an_py39/dependencies.py hl[3,6:8] title["app/dependencies.py"] *}

/// tip

We are using an invented header to simplify this example.

The status codes in the 400 range mean that there was an error from the client.

Remember all those **"404 Not Found"** errors (and jokes)?

## Use `HTTPException` { #use-httpexception }

To return HTTP responses with errors to the client you use `HTTPException`.

### Import `HTTPException` { #import-httpexception }

│   ├── main.py
│   └── test_main.py
```

이제 **FastAPI** 앱이 있는 `main.py` 파일에 몇 가지 다른 **경로 작업** 이 추가된 경우를 생각해봅시다.

단일 오류를 반환할 수 있는 `GET` 작업이 있습니다.

여러 다른 오류를 반환할 수 있는 `POST` 작업이 있습니다.

두 *경로 작업* 모두 `X-Token` 헤더를 요구합니다.

//// tab | Python 3.10+

```Python
{!> ../../docs_src/app_testing/app_b_an_py310/main.py!}
```

////

//// tab | Python 3.9+

```Python