and the
    [FastAPI docs for Response Model](https://fastapi.tiangolo.com/tutorial/response-model/).

    **Note**: `orjson` is not included with FastAPI and must be installed
    separately, e.g. `pip install orjson`.
    """

    def render(self, content: Any) -> bytes:
        assert orjson is not None, "orjson must be installed to use ORJSONResponse"
        return orjson.dumps(

from typing import Any

import orjson
from fastapi import FastAPI, Response

app = FastAPI()


class CustomORJSONResponse(Response):
    media_type = "application/json"

    def render(self, content: Any) -> bytes:
        assert orjson is not None, "orjson must be installed"
        return orjson.dumps(content, option=orjson.OPT_INDENT_2)


@app.get("/", response_class=CustomORJSONResponse)
async def main():

You can create your own custom response class, inheriting from `Response` and using it.

For example, let's say that you want to use [`orjson`](https://github.com/ijl/orjson) with some settings.

Let's say you want it to return indented and formatted JSON, so you want to use the orjson option `orjson.OPT_INDENT_2`.

from typing import Any

import orjson
from fastapi import APIRouter, FastAPI
from fastapi.responses import HTMLResponse, JSONResponse, PlainTextResponse
from fastapi.testclient import TestClient


class ORJSONResponse(JSONResponse):
    media_type = "application/x-orjson"

    def render(self, content: Any) -> bytes:
        return orjson.dumps(content)


class OverrideResponse(JSONResponse):
    media_type = "application/x-override"

```json
{
  "message": "Hello World"
}
```

當然，你大概能找到比格式化 JSON 更好的方式來利用這個能力。😉

### `orjson` 或回應模型 { #orjson-or-response-model }

如果你追求效能，使用[回應模型](../tutorial/response-model.md) 大概會比使用 `orjson` 回應更好。

有了回應模型，FastAPI 會使用 Pydantic 直接將資料序列化為 JSON，而不需要像其他情況那樣先經過 `jsonable_encoder` 之類的中介步驟。

而且在底層，Pydantic 用來序列化為 JSON 的 Rust 機制和 `orjson` 相同，因此用回應模型已經能獲得最佳效能。

## 預設回應類別 { #default-response-class }

::: fastapi.responses.UJSONResponse
    options:
        members:
            - charset
            - status_code
            - media_type
            - body
            - background
            - raw_headers
            - render
            - init_headers
            - headers
            - set_cookie

        response = client.get("/items")
    assert response.status_code == 200
    assert response.json() == {"name": "widget", "price": 9.99}


def test_orjson_response_emits_deprecation_warning():
    with pytest.warns(FastAPIDeprecationWarning, match="ORJSONResponse is deprecated"):
        ORJSONResponse(content={"hello": "world"})


# UJSON


def _make_ujson_app() -> FastAPI:
    with warnings.catch_warnings():

    "python-slugify >=8.0.4",
    "pyyaml >=5.3.1,<7.0.0",
    "typer >=0.21.1",
]
docs-tests = [
    "httpx >=0.23.0,<1.0.0",
    "ruff >=0.14.14",
    # For UJSONResponse
    "ujson >=5.8.0",
    # For ORJSONResponse
    "orjson >=3.9.3",
]
github-actions = [
    "httpx >=0.27.0,<1.0.0",
    "pydantic >=2.9.0,<3.0.0",
    "pydantic-settings >=2.1.0,<3.0.0",
    "pygithub >=2.3.0,<3.0.0",

Zusätzliche optionale FastAPI-Abhängigkeiten:

* [`orjson`](https://github.com/ijl/orjson) – erforderlich, wenn Sie `ORJSONResponse` verwenden möchten.
* [`ujson`](https://github.com/esnme/ultrajson) – erforderlich, wenn Sie `UJSONResponse` verwenden möchten.

## Lizenz { #license }

Додаткові необовʼязкові залежності FastAPI:

* [`orjson`](https://github.com/ijl/orjson) - потрібно, якщо ви хочете використовувати `ORJSONResponse`.
* [`ujson`](https://github.com/esnme/ultrajson) - потрібно, якщо ви хочете використовувати `UJSONResponse`.

## Ліцензія { #license }