buffer[bufferIndex + 2] = 1; // Error context count
        buffer[bufferIndex + 3] = 0; // Reserved
        SMBUtil.writeInt4(0, buffer, bufferIndex + 4); // ByteCount (0 for error)

        // Create a custom test response that tracks if readErrorResponse was called
        class TestSmb2ReadResponse extends Smb2ReadResponse {
            boolean errorResponseCalled = false;

{* ../../docs_src/dependencies/tutorial008b_an_py310.py hl[18:22,31] *}

Se você quiser capturar exceções e criar uma resposta personalizada com base nisso, crie um [Manipulador de Exceções Customizado](../handling-errors.md#install-custom-exception-handlers).

## Dependências com `yield` e `except` { #dependencies-with-yield-and-except }

Wenn Sie Exceptions abfangen und darauf basierend eine benutzerdefinierte Response erstellen möchten, erstellen Sie einen [benutzerdefinierten Exceptionhandler](../handling-errors.md#install-custom-exception-handlers).

## Abhängigkeiten mit `yield` und `except` { #dependencies-with-yield-and-except }

### 背景任務與含有 `yield` 的相依，技術細節 { #background-tasks-and-dependencies-with-yield-technical-details }

在 FastAPI 0.106.0 之前，不可能在 `yield` 之後拋出例外；含有 `yield` 的相依的結束程式碼會在回應送出之後才執行，因此[例外處理器](../tutorial/handling-errors.md#install-custom-exception-handlers) 早就已經跑完了。

當初這樣設計主要是為了允許在背景任務中使用由相依「yield」出來的同一組物件，因為結束程式碼會在背景任務結束後才執行。

在 FastAPI 0.106.0 中，這個行為被修改，目的是在等待回應穿越網路的期間，不要持有資源。

/// tip | 提示

此外，背景任務通常是一組獨立的邏輯，應該用自己的資源（例如自己的資料庫連線）來處理。

  /*
   * We avoid using a method reference or lambda here for now:
   *
   * - method reference: Inside Google, CacheBuilder is used from the implementation of a custom
   *   ClassLoader that is sometimes used as a system classloader. That's a problem because
   *   method-reference linking tries to look up the system classloader, and it fails because there
   *   isn't one yet.
   *

      return true;
    }
  }

  /**
   * Per <a href="https://github.com/google/guava/issues/1635">issue 1635</a>, In JDK 1.7.0_51-b13,
   * {@link TypeVariableImpl#equals(Object)} is changed to no longer be equal to custom TypeVariable
   * implementations. As a result, we need to make sure our TypeVariable implementation respects
   * symmetry. Moreover, we don't want to reconstruct a native type variable {@code <A>} using our

 * all elements in priority order and place them in another collection.
 *
 * <p>Operations on this class make no guarantees about the ordering of elements with equal
 * priority. If you need to enforce an ordering, you can define custom classes or comparators that
 * use a secondary key to break ties in primary priority values. For example, here is a class that
 * applies first-in-first-out tie-breaking to comparable elements. To use it, you would insert a

But you can also provide other alternative `servers`, for example if you want *the same* docs UI to interact with both a staging and a production environment.

If you pass a custom list of `servers` and there's a `root_path` (because your API lives behind a proxy), **FastAPI** will insert a "server" with this `root_path` at the beginning of the list.

For example:

{* ../../docs_src/query_params_str_validations/tutorial014_an_py310.py hl[10] *}

## Benutzerdefinierte Validierung { #custom-validation }

Es kann Fälle geben, in denen Sie eine **benutzerdefinierte Validierung** durchführen müssen, die nicht mit den oben gezeigten Parametern durchgeführt werden kann.

{* ../../docs_src/query_params_str_validations/tutorial014_an_py310.py hl[10] *}

## Validação personalizada { #custom-validation }

Podem existir casos em que você precise fazer alguma validação personalizada que não pode ser feita com os parâmetros mostrados acima.