# Exceptions - `HTTPException` and `WebSocketException`

These are the exceptions that you can raise to show errors to the client.

When you raise an exception, as would happen with normal Python, the rest of the execution is aborted. This way you can raise these exceptions from anywhere in the code to abort a request and show the error to the client.

You can use:

* `HTTPException`
* `WebSocketException`

        FastAPI,
        WebSocket,
        WebSocketException,
        status,
    )

    app = FastAPI()

    @app.websocket("/items/{item_id}/ws")
    async def websocket_endpoint(
        *,
        websocket: WebSocket,
        session: Annotated[str | None, Cookie()] = None,
        item_id: str,
    ):
        if session is None:
            raise WebSocketException(code=status.WS_1008_POLICY_VIOLATION)

from .background import BackgroundTasks as BackgroundTasks
from .datastructures import UploadFile as UploadFile
from .exceptions import HTTPException as HTTPException
from .exceptions import WebSocketException as WebSocketException
from .param_functions import Body as Body
from .param_functions import Cookie as Cookie
from .param_functions import Depends as Depends
from .param_functions import File as File

* `Query`

👫 👷 🎏 🌌 🎏 FastAPI 🔗/*➡ 🛠️*:

```Python hl_lines="66-77  76-91"
{!../../docs_src/websockets/tutorial002.py!}
```

/// info

👉 *️⃣ ⚫️ 🚫 🤙 ⚒ 🔑 🤚 `HTTPException`, ↩️ 👥 🤚 `WebSocketException`.

👆 💪 ⚙️ 📪 📟 ⚪️➡️ <a href="https://tools.ietf.org/html/rfc6455#section-7.4.1" class="external-link" target="_blank">☑ 📟 🔬 🔧</a>.

///

### 🔄 *️⃣ ⏮️ 🔗

🚥 👆 📁 📛 `main.py`, 🏃 👆 🈸 ⏮️:

{*../../docs_src/websockets/tutorial002_an_py310.py hl[68:69,82]*}

/// info | Informação

Como isso é um WebSocket, não faz muito sentido levantar uma `HTTPException`, em vez disso levantamos uma `WebSocketException`.

Você pode usar um código de fechamento dos <a href="https://tools.ietf.org/html/rfc6455#section-7.4.1" class="external-link" target="_blank">códigos válidos definidos na especificação</a>.

///

{!> ../../docs_src/websockets/tutorial002.py!}
```

////

/// info

Da es sich um einen WebSocket handelt, macht es keinen Sinn, eine `HTTPException` auszulösen, stattdessen lösen wir eine `WebSocketException` aus.

Sie können einen „Closing“-Code verwenden, aus den <a href="https://tools.ietf.org/html/rfc6455#section-7.4.1" class="external-link" target="_blank">gültigen Codes, die in der Spezifikation definiert sind</a>.

如果可能，请尽量使用 `Annotated` 版本。

///

```Python hl_lines="68-69  81"
{!> ../../docs_src/websockets/tutorial002.py!}
```

////

/// info

由于这是一个 WebSocket，抛出 `HTTPException` 并不是很合理，而是抛出 `WebSocketException`。

您可以使用<a href="https://tools.ietf.org/html/rfc6455#section-7.4.1" class="external-link" target="_blank">规范中定义的有效代码</a>。

///

### 尝试带有依赖项的 WebSockets

如果您的文件名为 `main.py`，请使用以下命令运行应用程序：

```Python hl_lines="68-69  81"
{!> ../../docs_src/websockets/tutorial002.py!}
```

////

/// info

As this is a WebSocket it doesn't really make sense to raise an `HTTPException`, instead we raise a `WebSocketException`.

You can use a closing code from the <a href="https://tools.ietf.org/html/rfc6455#section-7.4.1" class="external-link" target="_blank">valid codes defined in the specification</a>.

///

クロージングコードは、<a href="https://tools.ietf.org/html/rfc6455#section-7.4.1" class="external-link" target="_blank">仕様で定義された有効なコード</a>の中から使用することができます。

将来的には、どこからでも `raise` できる `WebSocketException` が用意され、専用の例外ハンドラを追加できるようになる予定です。これは、Starlette の <a href="https://github.com/encode/starlette/pull/527" class="external-link" target="_blank">PR #527</a> に依存するものです。

///

### 依存関係を用いてWebSocketsを試してみる

* New [WebSocketException (and docs)](https://fastapi.tiangolo.com/advanced/websockets/#using-depends-and-others), re-exported from Starlette.