The actual callback is just an HTTP request.

When implementing the callback yourself, you could use something like <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a> or <a href="https://requests.readthedocs.io/" class="external-link" target="_blank">Requests</a>.

///

## Write the callback documentation code { #write-the-callback-documentation-code }

* <a href="https://cdn.jsdelivr.net/npm/swagger-ui-dist@5/swagger-ui.css" class="external-link" target="_blank">`swagger-ui.css`</a>

And **ReDoc** uses the file:

* <a href="https://cdn.jsdelivr.net/npm/redoc@2/bundles/redoc.standalone.js" class="external-link" target="_blank">`redoc.standalone.js`</a>

O callback real é apenas um request HTTP.

Ao implementar o callback por conta própria, você pode usar algo como <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a> ou <a href="https://requests.readthedocs.io/" class="external-link" target="_blank">Requests</a>.

///

## Escreva o código de documentação do callback { #write-the-callback-documentation-code }

/// info

This requires installing `orjson` for example with `pip install orjson`.

///

### `UJSONResponse` { #ujsonresponse }

An alternative JSON response using <a href="https://github.com/ultrajson/ultrajson" class="external-link" target="_blank">`ujson`</a>.

/// info

/// info | Info

Dazu muss `orjson` installiert werden, z. B. mit `pip install orjson`.

///

### `UJSONResponse` { #ujsonresponse }

Eine alternative JSON-Response mit <a href="https://github.com/ultrajson/ultrajson" class="external-link" target="_blank">`ujson`</a>.

/// info | Info

* [Interner Link](index.md#installation){.internal-link target=_blank}
* <a href="https://sqlmodel.tiangolo.com/" class="external-link" target="_blank">Externer Link</a>
* <a href="https://fastapi.tiangolo.com/css/styles.css" class="external-link" target="_blank">Link zu einem Stil</a>
* <a href="https://fastapi.tiangolo.com/js/logic.js" class="external-link" target="_blank">Link zu einem Skript</a>

但 FastAPI 还可以使用数据类（<a href="https://docs.python.org/3/library/dataclasses.html" class="external-link" target="_blank">`dataclasses`</a>）：

{* ../../docs_src/dataclasses_/tutorial001.py hl[1,7:12,19:20] *}

这还是借助于 **Pydantic** 及其<a href="https://pydantic-docs.helpmanual.io/usage/dataclasses/#use-of-stdlib-dataclasses-with-basemodel" class="external-link" target="_blank">内置的 `dataclasses`</a>。

So, a `datetime` object would have to be converted to a `str` containing the data in <a href="https://en.wikipedia.org/wiki/ISO_8601" class="external-link" target="_blank">ISO format</a>.

The same way, this database wouldn't receive a Pydantic model (an object with attributes), only a `dict`.

You can use `jsonable_encoder` for that.

请记住可以 <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">用'X-' 前缀</a>添加专有自定义请求头.

但是如果你想让浏览器中的客户端看到你的自定义请求头, 你需要把它们加到 CORS 配置 ([CORS (Cross-Origin Resource Sharing)](cors.md){.internal-link target=_blank}) 的 `expose_headers` 参数中,在 <a href="https://www.starlette.dev/middleware/#corsmiddleware" class="external-link" target="_blank">Starlette's CORS docs</a>文档中.

///

/// note | 技术细节

Вы увидите автоматическую документацию API для основного приложения, включающую только его собственные _операции пути_:

<img src="/img/tutorial/sub-applications/image01.png">

Затем откройте документацию для подприложения по адресу <a href="http://127.0.0.1:8000/subapi/docs" class="external-link" target="_blank">http://127.0.0.1:8000/subapi/docs</a>.