import time

from fastapi import FastAPI, Request

app = FastAPI()


@app.middleware("http")
async def add_process_time_header(request: Request, call_next):
    start_time = time.perf_counter()
    response = await call_next(request)
    process_time = time.perf_counter() - start_time
    response.headers["X-Process-Time"] = str(process_time)

    yield request_state
    legacy_request_state_context_var.reset(contextvar_token)


@app.middleware("http")
async def custom_middleware(
    request: Request, call_next: Callable[[Request], Awaitable[Response]]
):
    response = await call_next(request)
    response.headers["custom"] = "foo"
    return response


@app.get("/user", dependencies=[Depends(set_up_request_state_dependency)])
def get_user():

        )

    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)


def test_async_state():

///

## Criar um middleware { #create-a-middleware }

Para criar um middleware, use o decorador `@app.middleware("http")` logo acima de uma função.

A função middleware recebe:

* A `request`.
* Uma função `call_next` que receberá o `request` como um parâmetro.
    * Esta função passará a `request` para a *operação de rota* correspondente.
    * Então ela retorna a `response` gerada pela *operação de rota* correspondente.

///

## Создание middleware { #create-a-middleware }

Для создания middleware используйте декоратор `@app.middleware("http")`.

Функция middleware получает:

* `request` (объект запроса).
* Функцию `call_next`, которая получает `request` в качестве параметра.
    * Эта функция передаёт `request` соответствующей *операции пути*.
    * Затем она возвращает ответ `response`, сгенерированный *операцией пути*.

Um eine Middleware zu erstellen, verwenden Sie den Dekorator `@app.middleware("http")` über einer Funktion.

Die Middleware-Funktion erhält:

* Den `request`.
* Eine Funktion `call_next`, die den `request` als Parameter erhält.
    * Diese Funktion gibt den `request` an die entsprechende *Pfadoperation* weiter.
    * Dann gibt es die von der entsprechenden *Pfadoperation* generierte `response` zurück.

///

## Crear un middleware { #create-a-middleware }

Para crear un middleware usas el decorador `@app.middleware("http")` encima de una función.

La función middleware recibe:

* La `request`.
* Una función `call_next` que recibirá la `request` como parámetro.
    * Esta función pasará la `request` a la correspondiente *path operation*.
    * Luego devuelve la `response` generada por la correspondiente *path operation*.

## Create a middleware { #create-a-middleware }

To create a middleware you use the decorator `@app.middleware("http")` on top of a function.

The middleware function receives:

* The `request`.
* A function `call_next` that will receive the `request` as a parameter.
    * This function will pass the `request` to the corresponding *path operation*.
    * Then it returns the `response` generated by the corresponding *path operation*.

        app = FastAPI()


        @app.middleware("http")
        async def add_process_time_header(
            request: Request, call_next: Callable[[Request], Awaitable[Response]]
        ) -> Response:
            start_time = time.time()
            response = await call_next(request)
            process_time = time.time() - start_time
            response.headers["X-Process-Time"] = str(process_time)