app = SomeASGIApp()

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

But FastAPI (actually Starlette) provides a simpler way to do it that makes sure that the internal middlewares to handle server errors and custom exception handlers work properly.

For that, you use `app.add_middleware()` (as in the example for CORS).

```Python
from fastapi import FastAPI
from unicorn import UnicornMiddleware

app = FastAPI()

from fastapi import FastAPI, HTTPException
from fastapi.exception_handlers import (
    http_exception_handler,
    request_validation_exception_handler,
)
from fastapi.exceptions import RequestValidationError
from starlette.exceptions import HTTPException as StarletteHTTPException

app = FastAPI()


@app.exception_handler(StarletteHTTPException)
async def custom_http_exception_handler(request, exc):
    print(f"OMG! An HTTP error!: {repr(exc)}")

假设要触发的自定义异常叫作 `UnicornException`。

且需要 FastAPI 实现全局处理该异常。

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

& 👆 💚 🍵 👉 ⚠ 🌐 ⏮️ FastAPI.

👆 💪 🚮 🛃 ⚠ 🐕‍🦺 ⏮️ `@app.exception_handler()`:

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

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

✋️ ⚫️ 🔜 🍵 `unicorn_exception_handler`.

, 👆 🔜 📨 🧹 ❌, ⏮️ 🇺🇸🔍 👔 📟 `418` & 🎻 🎚:

```JSON

from fastapi.routing import APIRoute


class TimedRoute(APIRoute):
    def get_route_handler(self) -> Callable:
        original_route_handler = super().get_route_handler()

        async def custom_route_handler(request: Request) -> Response:
            before = time.time()
            response: Response = await original_route_handler(request)
            duration = time.time() - before

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

from fastapi.exceptions import RequestValidationError
from fastapi.responses import JSONResponse
from pydantic import BaseModel

app = FastAPI()


@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request: Request, exc: RequestValidationError):
    return JSONResponse(
        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,

{!../../../docs_src/custom_request_and_route/tutorial001.py!}
```

### 创建自定义 `GzipRoute` 类

接下来，创建使用 `GzipRequest` 的 `fastapi.routing.APIRoute  ` 的自定义子类。

此时，这个自定义子类会覆盖 `APIRoute.get_route_handler()`。

`APIRoute.get_route_handler()` 方法返回的是函数，并且返回的函数接收请求并返回响应。

本例用它根据原始请求创建 `GzipRequest`。

```Python hl_lines="18-26"
{!../../../docs_src/custom_request_and_route/tutorial001.py!}
```

!!! note "技术细节"

            - post
            - delete
            - options
            - head
            - patch
            - trace
            - on_event
            - middleware

Routes are declared in a single place, using functions declared in other places (instead of using decorators that can be placed right on top of the function that handles the endpoint). This is closer to how Django does it than to how Flask (and Starlette) does it. It separates in the code things that are relatively tightly coupled.

!!! check "Inspired **FastAPI** to"