from fastapi import FastAPI
from fastapi.responses import UJSONResponse

app = FastAPI()


@app.get("/items/", response_class=UJSONResponse)
async def read_items():

    import ujson
except ImportError:  # pragma: nocover
    ujson = None  # type: ignore


try:
    import orjson
except ImportError:  # pragma: nocover
    orjson = None  # type: ignore


class UJSONResponse(JSONResponse):
    """
    JSON response using the high-performance ujson library to serialize data to JSON.

    Read more about it in the

    ORJSONResponse,
    PlainTextResponse,
    RedirectResponse,
    Response,
    StreamingResponse,
    UJSONResponse,
)
```

## FastAPI Responses

There are a couple of custom FastAPI response classes, you can use them to optimize JSON performance.

::: fastapi.responses.UJSONResponse
    options:
        members:
            - charset
            - status_code
            - media_type

如上文所述，这是 **FastAPI** 中使用的默认响应。

### `ORJSONResponse`

如上文所述，`ORJSONResponse` 是一个使用 <a href="https://github.com/ijl/orjson" class="external-link" target="_blank">`orjson`</a> 的快速的可选 JSON 响应。


### `UJSONResponse`

`UJSONResponse` 是一个使用 <a href="https://github.com/ultrajson/ultrajson" class="external-link" target="_blank">`ujson`</a> 的可选 JSON 响应。

/// warning | 警告

在处理某些边缘情况时，`ujson` 不如 Python 的内置实现那么谨慎。

///

    # For Starlette's SessionMiddleware, not commonly used with FastAPI
    "itsdangerous >=1.1.0",
    # For Starlette's schema generation, would not be used with FastAPI
    "pyyaml >=5.3.1",
    # For UJSONResponse
    "ujson >=4.0.1,!=4.0.2,!=4.1.0,!=4.2.0,!=4.3.0,!=5.0.0,!=5.1.0",
    # For ORJSONResponse
    "orjson >=3.2.1",
    # To validate email fields
    "email-validator >=2.0.0",
    # Uvicorn with uvloop