In general, ASGI middlewares are classes that expect to receive an ASGI app as the first argument.

So, in the documentation for third-party ASGI middlewares they will probably tell you to do something like:

```Python
from unicorn import UnicornMiddleware

app = SomeASGIApp()

new_app = UnicornMiddleware(app, some_config="rainbow")
```

此时，可以用 `@app.exception_handler()` 添加自定义异常控制器：

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

```

请求 `/unicorns/yolo` 时，路径操作会触发 `UnicornException`。

但该异常将会被 `unicorn_exception_handler` 处理。

接收到的错误信息清晰明了，HTTP 状态码为 `418`，JSON 内容如下：

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

```

!!! note "技术细节"

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

📥, 🚥 👆 📨 `/unicorns/yolo`, *➡ 🛠️* 🔜 `raise` `UnicornException`.

✋️ ⚫️ 🔜 🍵 `unicorn_exception_handler`.

, 👆 🔜 📨 🧹 ❌, ⏮️ 🇺🇸🔍 👔 📟 `418` & 🎻 🎚:

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

!!! note "📡 ℹ"

Với **FastAPI**, bạn có được tất cả những tính năng của **Starlette**:

* Hiệu năng thực sự ấn tượng. Nó là <a href="https://github.com/encode/starlette#performance" class="external-link" target="_blank">một trong nhưng framework Python nhanh nhất, khi so sánh với **NodeJS** và **Go**</a>.
* Hỗ trợ **WebSocket**.
* In-process background tasks.

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

!!! note "技術詳細"

    Hug inspired **FastAPI** to declare a `response` parameter in functions to set headers and cookies.

### <a href="https://github.com/encode/apistar" class="external-link" target="_blank">APIStar</a> (<= 0.5)

Right before deciding to build **FastAPI** I found **APIStar** server. It had almost everything I was looking for and had a great design.

    🤗 😮 🍕 APIStar, & 1️⃣ 🧰 👤 🔎 🏆 👍, 🌟 APIStar.

    🤗 ℹ 😍 **FastAPI** ⚙️ 🐍 🆎 🔑 📣 🔢, & 🏗 🔗 ⚖ 🛠️ 🔁.

    🤗 😮 **FastAPI** 📣 `response` 🔢 🔢 ⚒ 🎚 & 🍪.

### <a href="https://github.com/encode/apistar" class="external-link" target="_blank">APIStar</a> (&lt;= 0️⃣.5️⃣)

▶️️ ⏭ 🤔 🏗 **FastAPI** 👤 🔎 **APIStar** 💽. ⚫️ ✔️ 🌖 🌐 👤 👀 &amp; ✔️ 👑 🔧.

You can also use <a href="https://github.com/encode/databases" class="external-link" target="_blank">`encode/databases`</a> with **FastAPI** to connect to databases using `async` and `await`.

It is compatible with:

* PostgreSQL
* MySQL
* SQLite

In this example, we'll use **SQLite**, because it uses a single file and Python has integrated support. So, you can copy this example and run it as is.

    Wenn Sie etwas benötigen, das sich leicht in FastAPI integrieren lässt, aber robuster ist und von Redis, PostgreSQL und anderen unterstützt wird, sehen Sie sich <a href="https://github.com/encode/broadcaster" class="external-link" target="_blank">encode/broadcaster</a> an.

## Mehr Informationen

Weitere Informationen zu Optionen finden Sie in der Dokumentation von Starlette:

    * Document better how to handle exceptions and use error handlers.
    * Include `RequestValidationError` and `WebSocketRequestValidationError` (this last one will be useful once [encode/starlette#527](https://github.com/encode/starlette/pull/527) or equivalent is merged).
    * New documentation about exceptions handlers: