opt raise
        dep -->> handler: Raise HTTPException
        handler -->> client: HTTP error response
        dep -->> dep: Raise other exception
    end
    dep ->> operation: Run dependency, e.g. DB session
    opt raise
        operation -->> dep: Raise HTTPException
        dep -->> handler: Auto forward exception
        handler -->> client: HTTP error response

This was changed in version 0.110.0 to fix unhandled memory consumption from forwarded exceptions without a handler (internal server errors), and to make it consistent with the behavior of regular Python code.

!!! tip

    在`yield`之前仍然可以引发包括`HTTPException`在内的异常，但在`yield`之后则不行。

执行的顺序大致如下图所示。时间从上到下流动。每列都是相互交互或执行代码的其中一部分。

```mermaid
sequenceDiagram

participant client as Client
participant handler as Exception handler
participant dep as Dep with yield
participant operation as Path Operation

Sie könnten einen benutzerdefinierten Exceptionhandler mittels `@app.exception_handler()` hinzufügen:

```Python hl_lines="5-7  13-18  24"
{!../../../docs_src/handling_errors/tutorial003.py!}
```

Wenn Sie nun `/unicorns/yolo` anfragen, `raise`d die *Pfadoperation* eine `UnicornException`.

Aber diese wird von `unicorn_exception_handler` gehandhabt.

Можно добавить собственный обработчик исключений с помощью `@app.exception_handler()`:

```Python hl_lines="5-7  13-18  24"
{!../../../docs_src/handling_errors/tutorial003.py!}
```

Здесь, если запросить `/unicorns/yolo`, то *операция пути* вызовет `UnicornException`.

Но оно будет обработано `unicorn_exception_handler`.

Таким образом, вы получите чистую ошибку с кодом состояния HTTP `418` и содержимым JSON:

```Python hl_lines="5-7  13-18  24"
{!../../../docs_src/handling_errors/tutorial003.py!}
```

Nesse cenário, se você fizer uma requisição para `/unicorns/yolo`, a *operação de caminho* vai lançar (`raise`) o `UnicornException`.

Essa exceção será manipulada, contudo, pelo `unicorn_exception_handler`.

#### CRD Watcher

そして、この例外をFastAPIでグローバルに処理したいと思います。

カスタム例外ハンドラを`@app.exception_handler()`で追加することができます:

```Python hl_lines="5 6 7  13 14 15 16 17 18  24"
{!../../../docs_src/handling_errors/tutorial003.py!}
```

ここで、`/unicorns/yolo`をリクエストすると、*path operation*は`UnicornException`を`raise`します。

しかし、これは`unicorn_exception_handler`で処理されます。

そのため、HTTPステータスコードが`418`で、JSONの内容が以下のような明確なエラーを受け取ることになります:

```JSON

    Note over dep: Run code up to yield
    opt raise
        dep -->> handler: Raise HTTPException
        handler -->> client: HTTP error response
        dep -->> dep: Raise other exception
    end
    dep ->> operation: Run dependency, e.g. DB session
    opt raise
        operation -->> handler: Raise HTTPException
        handler -->> client: HTTP error response
        operation -->> dep: Raise other exception

    when (type) {
      TYPE_DATA -> readData(handler, length, flags, streamId)
      TYPE_HEADERS -> readHeaders(handler, length, flags, streamId)
      TYPE_PRIORITY -> readPriority(handler, length, flags, streamId)
      TYPE_RST_STREAM -> readRstStream(handler, length, flags, streamId)
      TYPE_SETTINGS -> readSettings(handler, length, flags, streamId)
      TYPE_PUSH_PROMISE -> readPushPromise(handler, length, flags, streamId)