## Использование `WSGIMiddleware` { #using-wsgimiddleware }

Нужно импортировать `WSGIMiddleware`.

Затем оберните WSGI‑приложение (например, Flask) в middleware (Промежуточный слой).

После этого смонтируйте его на путь.

{* ../../docs_src/wsgi/tutorial001_py39.py hl[2:3,3] *}

## Проверьте { #check-it }

En algunos casos, puede que quieras sobrescribir la lógica utilizada por las clases `Request` y `APIRoute`.

En particular, esta puede ser una buena alternativa a la lógica en un middleware.

Por ejemplo, si quieres leer o manipular el request body antes de que sea procesado por tu aplicación.

/// danger | Advertencia

Esta es una funcionalidad "avanzada".

клиенту в браузере, вам нужно добавить их в настройки CORS (подробнее см. в [CORS (Cross-Origin Resource Sharing)](../tutorial/cors.md){.internal-link target=_blank}), используя параметр `expose_headers`, описанный в <a href="https://www.starlette.dev/middleware/#corsmiddleware" class="external-link" target="_blank">документации Starlette по CORS</a>....

## Usando `WSGIMiddleware` { #using-wsgimiddleware }

Você precisa importar o `WSGIMiddleware`.

Em seguida, encapsule a aplicação WSGI (e.g. Flask) com o middleware.

E então monte isso sob um path.

{* ../../docs_src/wsgi/tutorial001_py39.py hl[2:3,3] *}

## Confira { #check-it }

Agora, todas as requisições sob o path `/v1/` serão manipuladas pela aplicação Flask.

# Custom Request and APIRoute class { #custom-request-and-apiroute-class }

In some cases, you may want to override the logic used by the `Request` and `APIRoute` classes.

In particular, this may be a good alternative to logic in a middleware.

For example, if you want to read or manipulate the request body before it is processed by your application.

/// danger

This is an "advanced" feature.

## `WSGIMiddleware` verwenden { #using-wsgimiddleware }

Sie müssen `WSGIMiddleware` importieren.

Wrappen Sie dann die WSGI-Anwendung (z. B. Flask) mit der Middleware.

Und dann mounten Sie das auf einem Pfad.

{* ../../docs_src/wsgi/tutorial001_py39.py hl[2:3,3] *}

## Es testen { #check-it }

        state["sync_bg"] = (
            f"sync_bg set - b: {state['context_b']} - a: {state['context_a']}"
        )

    tasks.add_task(bg, state)
    return state


@app.middleware("http")
async def middleware(request, call_next):
    response: StreamingResponse = await call_next(request)
    response.headers["x-state"] = json.dumps(state.copy())
    return response


client = TestClient(app)

///

## 自定义头部

请注意，可以使用'X-'前缀添加自定义专有头部。

você precisa adicioná-los às suas configurações de CORS (saiba mais em [CORS (Cross-Origin Resource Sharing)](../tutorial/cors.md){.internal-link target=_blank}), usando o parâmetro `expose_headers` descrito na <a href="https://www.starlette.dev/middleware/#corsmiddleware" class="external-link" target="_blank">documentação de CORS do Starlette</a>....

/// note | 技术细节

你也可以使用 `from starlette.middleware.cors import CORSMiddleware`。

出于方便，**FastAPI** 在 `fastapi.middleware` 中为开发者提供了几个中间件。但是大多数可用的中间件都是直接来自 Starlette。