class JsonApiError(BaseModel):
    errors: typing.List[Error]


@app.get(
    "/a",
    response_class=JsonApiResponse,
    responses={500: {"description": "Error", "model": JsonApiError}},
)
async def a():
    pass  # pragma: no cover


@app.get("/b", responses={500: {"description": "Error", "model": Error}})
async def b():
    pass  # pragma: no cover


client = TestClient(app)

    status: str
    title: str


class JsonApiError(BaseModel):
    errors: typing.List[Error]


@app.get(
    "/a",
    status_code=204,
    response_class=JsonApiResponse,
    responses={500: {"description": "Error", "model": JsonApiError}},
)
async def a():
    pass


@app.get("/b", responses={204: {"description": "No Content"}})
async def b():
    pass  # pragma: no cover

async def callback5(level5: str):
    pass  # pragma: nocover


app = FastAPI(
    dependencies=[Depends(dep0)],
    responses={
        400: {"description": "Client error level 0"},
        500: {"description": "Server error level 0"},
    },
    default_response_class=ResponseLevel0,
    callbacks=callback_router0.routes,
)

router2_override = APIRouter(
    prefix="/level2",

    from docs_src.dependencies.tutorial008d_an import app

    client = TestClient(app, raise_server_exceptions=False)
    response = client.get("/items/portal-gun")
    assert response.status_code == 500, response.text

                    </mxGeometry>
                </mxCell>
                <mxCell id="33" value="" style="group" parent="1" vertex="1" connectable="0">
                    <mxGeometry x="-140" y="-75" width="500" height="350" as="geometry"/>
                </mxCell>

```Python hl_lines="2  6"
{!../../../docs_src/advanced_middleware/tutorial003.py!}
```

The following arguments are supported:

* `minimum_size` - Do not GZip responses that are smaller than this minimum size in bytes. Defaults to `500`.

## Other middlewares

There are many other ASGI middlewares.

For example:

* <a href="https://docs.sentry.io/platforms/python/guides/fastapi/" class="external-link" target="_blank">Sentry</a>

    from docs_src.dependencies.tutorial008d import app

    client = TestClient(app, raise_server_exceptions=False)
    response = client.get("/items/portal-gun")
    assert response.status_code == 500, response.text

* **`300`** & 🔛 "❎". 📨 ⏮️ 👫 👔 📟 5️⃣📆 ⚖️ 5️⃣📆 🚫 ✔️ 💪, 🌖 `304`, "🚫 🔀", ❔ 🔜 🚫 ✔️ 1️⃣.
* **`400`** & 🔛 "👩‍💻 ❌" 📨. 👫 🥈 🆎 👆 🔜 🎲 ⚙️ 🏆.
    * 🖼 `404`, "🚫 🔎" 📨.
    * 💊 ❌ ⚪️➡️ 👩‍💻, 👆 💪 ⚙️ `400`.
* `500` & 🔛 💽 ❌. 👆 🌖 🙅 ⚙️ 👫 🔗. 🕐❔ 🕳 🚶 ❌ 🍕 👆 🈸 📟, ⚖️ 💽, ⚫️ 🔜 🔁 📨 1️⃣ 👫 👔 📟.

!!! tip

**FastAPI** 调用的就是 `RequestValidationError` 类，因此，如果在 `response_model` 中使用 Pydantic 模型，且数据有错误时，在日志中就会看到这个错误。

但客户端或用户看不到这个错误。反之，客户端接收到的是 HTTP 状态码为 `500` 的「内部服务器错误」。

这是因为在*响应*或代码（不是在客户端的请求里）中出现的 Pydantic `ValidationError` 是代码的 bug。

修复错误时，客户端或用户不能访问错误的内部信息，否则会造成安全隐患。

### 覆盖 `HTTPException` 错误处理器

同理，也可以覆盖 `HTTPException` 处理器。

def request_validation_exception_handler(request, exception):
    return JSONResponse({"exception": "request-validation"})


def server_error_exception_handler(request, exception):
    return JSONResponse(status_code=500, content={"exception": "server-error"})


app = FastAPI(
    exception_handlers={
        HTTPException: http_exception_handler,
        RequestValidationError: request_validation_exception_handler,