class UnicornException(Exception):
    def __init__(self, name: str):
        self.name = name


app = FastAPI()


@app.exception_handler(UnicornException)
async def unicorn_exception_handler(request: Request, exc: UnicornException):
    return JSONResponse(
        status_code=418,
        content={"message": f"Oops! {exc.name} did something. There goes a rainbow..."},
    )

{* ../../docs_src/handling_errors/tutorial003_py310.py hl[5:7,13:18,24] *}

Here, if you request `/unicorns/yolo`, the *path operation* will `raise` a `UnicornException`.

But it will be handled by the `unicorn_exception_handler`.

So, you will receive a clean error, with an HTTP status code of `418` and a JSON content of:

```JSON
{"message": "Oops! yolo did something. There goes a rainbow..."}
```

{* ../../docs_src/handling_errors/tutorial003_py310.py hl[5:7,13:18,24] *}

Burada `/unicorns/yolo` için request atarsanız, *path operation* bir `UnicornException` `raise` eder.

Namun bu, `unicorn_exception_handler` tarafından handle edilir.

Böylece HTTP status code’u `418` olan, JSON içeriği şu şekilde temiz bir hata response’u alırsınız:

```JSON
{"message": "Oops! yolo did something. There goes a rainbow..."}
```

{* ../../docs_src/handling_errors/tutorial003_py310.py hl[5:7,13:18,24] *}

Aquí, si solicitas `/unicorns/yolo`, la *path operation* lanzará un `UnicornException`.

Pero será manejado por el `unicorn_exception_handler`.

Así que recibirás un error limpio, con un código de estado HTTP de `418` y un contenido JSON de:

```JSON
{"message": "Oops! yolo did something. There goes a rainbow..."}
```

你可以使用 `@app.exception_handler()` 加入自訂例外處理器：

{* ../../docs_src/handling_errors/tutorial003_py310.py hl[5:7,13:18,24] *}

在這裡，如果你請求 `/unicorns/yolo`，該「路徑操作」會 `raise` 一個 `UnicornException`。

但它會被 `unicorn_exception_handler` 所處理。

因此你會得到一個乾淨的錯誤回應，HTTP 狀態碼為 `418`，JSON 內容如下：

```JSON
{"message": "Oops! yolo did something. There goes a rainbow..."}
```

/// note | 技術細節