But this example is still valid and it shows how to interact with the internal components.

///

We can also use this same approach to access the request body in an exception handler.

All we need to do is handle the request inside a `try`/`except` block:

{* ../../docs_src/custom_request_and_route/tutorial002.py hl[13,15] *}

Le tout de manière à offrir la meilleure expérience de développement à tous les développeurs.

## Exigences

Après avoir testé plusieurs alternatives, j'ai décidé que j'allais utiliser <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">**Pydantic**</a> pour ses avantages.

        Optional<Long> size = byteSource.sizeIfKnown();
        // if we know the size and it fits in an int
        if (size.isPresent() && size.get().longValue() == size.get().intValue()) {
          // otherwise try to presize a StringBuilder
          // it is kind of lame that we need to construct a decoder to access this value.
          // if this is a concern we could add special cases for some known charsets (like utf8)

Ahora revisemos esos cambios paso a paso.

## Esquema de seguridad OAuth2

El primer cambio es que ahora estamos declarando el esquema de seguridad OAuth2 con dos scopes disponibles, `me` y `items`.

El parámetro `scopes` recibe un `dict` con cada scope como clave y la descripción como valor:

{* ../../docs_src/security/tutorial005_an_py310.py hl[63:66] *}

        return null // Nothing to do.
      }

      val now = backend.nanoTime()
      var minDelayNanos = Long.MAX_VALUE
      var readyTask: Task? = null
      var multipleReadyTasks = false

      // Decide what to run. This loop's goal wants to:
      //  * Find out what this thread should do (either run a task or sleep)
      //  * Find out if there's enough work to start another thread.

 * has zero slope).
 *
 * @author Pete Gillin
 * @since 20.0
 */
@J2ktIncompatible
@GwtIncompatible
public abstract class LinearTransformation {
  /**
   * Constructor for use by subclasses inside Guava.
   *
   * @deprecated Create instances by using the static factory methods of the class.
   */
  @Deprecated
  public LinearTransformation() {}

  /**

				CalculatedSHA256: "88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589",
			},
		},

		// Input with size more than the size of actual data inside the reader.
		8: {
			bucketName: bucket, objName: object, inputData: []byte("abcd"),
			inputMeta: map[string]string{"etag": "e2fc714c4727ee9395f324cd2e7f331e"}, inputDataSize: int64(len("abcd") + 1),

And as the write operation doesn't use `async` and `await`, we define the function with normal `def`:

{* ../../docs_src/background_tasks/tutorial001.py hl[6:9] *}

## Add the background task { #add-the-background-task }

Inside of your *path operation function*, pass your task function to the *background tasks* object with the method `.add_task()`:

{* ../../docs_src/background_tasks/tutorial001.py hl[14] *}

`.add_task()` receives as arguments:

## Installer le programme serveur

Vous pouvez installer un serveur compatible ASGI avec :

//// tab | Uvicorn

* <a href="https://www.uvicorn.org/" class="external-link" target="_blank">Uvicorn</a>, un serveur ASGI rapide comme l'éclair, basé sur uvloop et httptools.

<div class="termy">

```console
$ pip install "uvicorn[standard]"

---> 100%
```

</div>

/// tip | Astuce

Dentro de tu *path operation function*, pasa tu función de tarea al objeto de *background tasks* con el método `.add_task()`:

{* ../../docs_src/background_tasks/tutorial001.py hl[14] *}

`.add_task()` recibe como argumentos:

* Una función de tarea para ejecutar en segundo plano (`write_notification`).
* Cualquier secuencia de argumentos que deba pasarse a la función de tarea en orden (`email`).