# 扩展 OpenAPI { #extending-openapi }

在某些情况下，你可能需要修改生成的 OpenAPI 架构（schema）。

本节将介绍如何实现。

## 常规流程 { #the-normal-process }

常规（默认）流程如下。

`FastAPI` 应用（实例）有一个 `.openapi()` 方法，预期返回 OpenAPI 架构。

在创建应用对象时，会注册一个用于 `/openapi.json`（或你在 `openapi_url` 中设置的路径）的路径操作。

它只会返回一个 JSON 响应，内容是应用 `.openapi()` 方法的结果。

默认情况下，`.openapi()` 方法会检查属性 `.openapi_schema` 是否已有内容，若有则直接返回。

如果没有，则使用 `fastapi.openapi.utils.get_openapi` 工具函数生成。

 * after the garbage collector reclaims the referent. This is a simpler alternative to using a
 * {@link ReferenceQueue}.
 *
 * <p>Unlike a normal phantom reference, this reference will be cleared automatically.
 *
 * @author Bob Lee
 * @since 2.0
 */
@J2ktIncompatible
@GwtIncompatible

## HTTPX { #httpx }

Even if your **FastAPI** application uses normal `def` functions instead of `async def`, it is still an `async` application underneath.

### Otras funciones de utilidad { #other-utility-functions }

Cualquier otra función de utilidad que llames directamente puede ser creada con `def` normal o `async def` y FastAPI no afectará la forma en que la llames.

There are cases where you want to tell your API **users** that your app could call *their* app (sending a request) with some data, normally to **notify** of some type of **event**.

This means that instead of the normal process of your users sending requests to your API, it's **your API** (or your app) that could **send requests to their system** (to their API, their app).

This is normally called a **webhook**.

    fail("")
  }

  override fun ackSettings() {
    fail("")
  }

  override fun ping(
    ack: Boolean,
    payload1: Int,
    payload2: Int,
  ) {
    fail("")
  }

  override fun goAway(
    lastGoodStreamId: Int,
    errorCode: ErrorCode,
    debugData: ByteString,
  ) {
    fail("")
  }

  override fun windowUpdate(
    streamId: Int,
    windowSizeIncrement: Long,
  ) {

# OpenAPI erweitern { #extending-openapi }

Es gibt einige Fälle, in denen Sie das generierte OpenAPI-Schema ändern müssen.

In diesem Abschnitt erfahren Sie, wie.

## Der normale Vorgang { #the-normal-process }

Der normale (Standard-)Prozess ist wie folgt.

Eine `FastAPI`-Anwendung (Instanz) verfügt über eine `.openapi()`-Methode, von der erwartet wird, dass sie das OpenAPI-Schema zurückgibt.

 * </ol>
 *
 * <p><b>Other notes</b>
 *
 * <ul>
 *   <li>Usually, there is one testcase method per JSR166 method covering "normal" operation, and
 *       then as many exception-testing methods as there are exceptions the method can throw.
 *       Sometimes there are multiple tests per JSR166 method when the different "normal" behaviors
 *       differ significantly. And sometimes testcases cover multiple methods when they cannot be

It is just a standard function that can receive parameters.

It can be an `async def` or normal `def` function, **FastAPI** will know how to handle it correctly.

In this case, the task function will write to a file (simulating sending an email).

And as the write operation doesn't use `async` and `await`, we define the function with normal `def`:

{* ../../docs_src/background_tasks/tutorial001_py310.py hl[6:9] *}

    * Cela sera fait en envoyant une requête POST (depuis *votre API*) vers une *API externe* fournie par cette personne développeuse externe (c’est le « callback »).

## L’application **FastAPI** normale { #the-normal-fastapi-app }

Voyons d’abord à quoi ressemble l’application API normale avant d’ajouter le callback.