And it also includes a default exception handler for it.

To override it, import the `RequestValidationError` and use it with `@app.exception_handler(RequestValidationError)` to decorate the exception handler.

The exception handler will receive a `Request` and the exception.

{* ../../docs_src/handling_errors/tutorial004_py310.py hl[2,14:19] *}

   * right before each task is run. The renaming is best effort, if a {@link SecurityManager}
   * prevents the renaming then it will be skipped but the tasks will still execute.
   *
   * @param executor The executor to decorate
   * @param nameSupplier The source of names for each task
   */
  @J2ktIncompatible
  @GwtIncompatible // concurrency
  static Executor renamingDecorator(Executor executor, Supplier<String> nameSupplier) {

* [`@contextlib.asynccontextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager)

using them to decorate a function with a single `yield`.

That's what **FastAPI** uses internally for dependencies with `yield`.

But you don't have to use the decorators for FastAPI dependencies (and you shouldn't).

  /**
   * Results are posted here as they occur. The find job is done when either one plan completes
   * successfully or all plans fail.
   */
  private val connectResults = taskRunner.backend.decorate(LinkedBlockingDeque<ConnectResult>())

  override fun find(): RealConnection {
    var firstException: IOException? = null
    try {
      while (tcpConnectsInFlight.isNotEmpty() || routePlanner.hasNext()) {

Ve bunun için varsayılan bir exception handler da içerir.

Override etmek için `RequestValidationError`’ı import edin ve exception handler’ı `@app.exception_handler(RequestValidationError)` ile decorate edin.

Exception handler, bir `Request` ve exception’ı alır.

{* ../../docs_src/handling_errors/tutorial004_py310.py hl[2,14:19] *}

Artık `/items/foo`’ya giderseniz, şu varsayılan JSON hatası yerine:

* [`@contextlib.asynccontextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager)

Bunları, tek bir `yield` içeren bir fonksiyonu decorate etmek için kullanabilirsiniz.

FastAPI, `yield` kullanan dependency'ler için içeride bunu yapar.

Ancak FastAPI dependency'leri için bu decorator'ları kullanmak zorunda değilsiniz (hatta kullanmamalısınız).

        def decorator(func: DecoratedCallable) -> DecoratedCallable:
            self.add_route(
                path,
                func,
                methods=methods,
                name=name,
                include_in_schema=include_in_schema,
            )
            return func

        return decorator

    def add_api_route(
        self,

        ```
        """

        def decorator(func: DecoratedCallable) -> DecoratedCallable:
            self.add_api_websocket_route(
                path,
                func,
                name=name,
                dependencies=dependencies,
            )
            return func

        return decorator

    def include_router(
        self,

/// info | `@decorator` Info

Cette syntaxe `@something` en Python est appelée un « décorateur ».

Vous la mettez au-dessus d’une fonction. Comme un joli chapeau décoratif (j’imagine que c’est de là que vient le terme 🤷🏻‍♂).

Un « décorateur » prend la fonction en dessous et fait quelque chose avec.

Dans ces cas, au lieu de déclarer un paramètre de *fonction de chemin d'accès* avec `Depends`, vous pouvez ajouter une `list` de `dependencies` au *décorateur de chemin d'accès*.

## Ajouter `dependencies` au *décorateur de chemin d'accès* { #add-dependencies-to-the-path-operation-decorator }

Le *décorateur de chemin d'accès* accepte un argument optionnel `dependencies`.

Il doit s'agir d'une `list` de `Depends()` :