Якщо у Вас є залежності з `yield`, код виходу виконається *після* middleware.

Якщо були заплановані фонові задачі (background tasks - розглянуто далі), вони виконаються *після* всіх middleware.

///

## Створення middleware

Щоб створити middleware, Ви використовуєте декоратор `@app.middleware("http")` на функції.

Функція middleware отримує:

* `Запит`.
* Функцію `call_next`, яка приймає `запит` як параметр.

* **Request**: MiddlewareB → MiddlewareA → route

* **Response**: route → MiddlewareA → MiddlewareB

This stacking behavior ensures that middlewares are executed in a predictable and controllable order.

## Other middlewares { #other-middlewares }

You can later read more about other middlewares in the [Advanced User Guide: Advanced Middleware](../advanced/middleware.md){.internal-link target=_blank}.

# Advanced Middleware { #advanced-middleware }

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 }

/// note | Technical Details

You could also use `from starlette.middleware.cors import CORSMiddleware`.

**FastAPI** provides several middlewares in `fastapi.middleware` just as a convenience for you, the developer. But most of the available middlewares come directly from Starlette.

**FastAPI** надає кілька middleware у `fastapi.middleware` для зручності розробників. Але більшість доступних middleware походять безпосередньо зі Starlette.

      - tutorial/security/index.md
      - tutorial/security/first-steps.md
      - tutorial/security/get-current-user.md
      - tutorial/security/simple-oauth2.md
      - tutorial/security/oauth2-jwt.md
    - tutorial/middleware.md
    - tutorial/cors.md
    - tutorial/sql-databases.md
    - tutorial/bigger-applications.md
    - tutorial/background-tasks.md
    - tutorial/metadata.md
    - tutorial/static-files.md

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

You need to import `WSGIMiddleware`.

Then wrap the WSGI (e.g. Flask) app with the middleware.

And then mount that under a path.

{* ../../docs_src/wsgi/tutorial001.py hl[2:3,3] *}

## Check it { #check-it }

Now, every request under the path `/v1/` will be handled by the Flask application.

# 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.

		// Wrap the actual handler with the appropriate tracing middleware.
		var tracedHandler http.HandlerFunc
		if handlerFlags.has(traceHdrsS3HFlag) {
			tracedHandler = httpTraceHdrs(f)
		} else {
			tracedHandler = httpTraceAll(f)
		}

		// Skip wrapping with the gzip middleware if specified.
		gzippedHandler := tracedHandler
		if !handlerFlags.has(noGZS3HFlag) {

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.io/middleware/#corsmiddleware" class="external-link" target="_blank">Starlette's CORS docs</a>....