have custom headers that you want a client in a browser to be able to see, you need to add them to your CORS configurations (read more in [CORS (Cross-Origin Resource Sharing)](../tutorial/cors.md){.internal-link target=_blank}), using the parameter `expose_headers` documented in <a href="https://www.starlette.dev/middleware/#corsmiddleware" class="external-link" target="_blank">Starlette's CORS docs</a>....

ただし、ブラウザのクライアントに表示させたいカスタムヘッダーがある場合は、<a href="https://www.starlette.dev/middleware/#corsmiddleware" class="external-link" target="_blank">StarletteのCORSドキュメント</a>に記載されているパラメータ `expose_headers` を使用して、それらをCORS設定に追加する必要があります ([CORS (オリジン間リソース共有)](cors.md){.internal-link target=_blank})

///

/// note | 技術詳細

`from starlette.requests import Request` を使用することもできます。

///

/// note | Detalles Técnicos

target="_blank">‘X-’ 접두어를 사용하여</a> 커스텀 사설 헤더를 추가할 수 있습니다.

하지만, 여러분이 브라우저에서 클라이언트가 볼 수 있기를 원하는 커스텀 헤더가 있는 경우, CORS 설정에 이를 추가해야 합니다([CORS (Cross-Origin Resource Sharing)](../tutorial/cors.md){.internal-link target=_blank}에서 자세히 알아보세요). `expose_headers` 매개변수를 사용하여 <a href="https://www.starlette.dev/middleware/#corsmiddleware" class="external-link" target="_blank">Starlette의 CORS 설명서</a>에 문서화된 대로 설정할 수 있습니다....

En el tutorial principal leíste cómo agregar [Middleware Personalizado](../tutorial/middleware.md){.internal-link target=_blank} a tu aplicación.

Y luego también leíste cómo manejar [CORS con el `CORSMiddleware`](../tutorial/cors.md){.internal-link target=_blank}.

En esta sección veremos cómo usar otros middlewares.

## Agregando middlewares ASGI { #adding-asgi-middlewares }

from fastapi.testclient import TestClient

from docs_src.cors.tutorial001_py39 import app


def test_cors():
    client = TestClient(app)
    # Test pre-flight response
    headers = {
        "Origin": "https://localhost.tiangolo.com",
        "Access-Control-Request-Method": "GET",
        "Access-Control-Request-Headers": "X-Example",
    }
    response = client.options("/", headers=headers)

personalizados que quieres que un cliente en un navegador pueda ver, necesitas agregarlos a tus configuraciones de CORS (leer más en [CORS (Cross-Origin Resource Sharing)](../tutorial/cors.md){.internal-link target=_blank}), usando el parámetro `expose_headers` documentado en <a href="https://www.starlette.dev/middleware/#corsmiddleware" class="external-link" target="_blank">la documentación CORS de Starlette</a>....

But if you have custom headers that you want a client in a browser to be able to see, you need to add them to your CORS configurations ([CORS (Cross-Origin Resource Sharing)](cors.md){.internal-link target=_blank}) using the parameter `expose_headers` documented in <a href="https://www.starlette.dev/middleware/#corsmiddleware" class="external-link" target="_blank">Starlette's CORS docs</a>.

///

/// note | Technical Details

In the main tutorial you read how to add [Custom Middleware](../tutorial/middleware.md){.internal-link target=_blank} to your application.

And then you also read how to handle [CORS with the `CORSMiddleware`](../tutorial/cors.md){.internal-link target=_blank}.

In this section we'll see how to use other middlewares.

## Adding ASGI middlewares { #adding-asgi-middlewares }

			Queries("cors", "")
		// PutBucketCors - this is a dummy call.
		router.Methods(http.MethodPut).
			HandlerFunc(s3APIMiddleware(api.PutBucketCorsHandler)).
			Queries("cors", "")
		// DeleteBucketCors - this is a dummy call.
		router.Methods(http.MethodDelete).
			HandlerFunc(s3APIMiddleware(api.DeleteBucketCorsHandler)).
			Queries("cors", "")
		// GetBucketWebsiteHandler - this is a dummy call.