Aqui veremos um exemplo usando <a href="https://sqlmodel.tiangolo.com/" class="external-link" target="_blank">SQLModel</a>.

/// note | 기술 세부사항

다음과 함께 사용할 수 있는 모든 함수:

* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager" class="external-link" target="_blank">`@contextlib.contextmanager`</a> 또는
* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager" class="external-link" target="_blank">`@contextlib.asynccontextmanager`</a>

는 **FastAPI**의 의존성으로 사용할 수 있습니다.

사실, FastAPI는 내부적으로 이 두 데코레이터를 사용합니다.

///

 * those tasks.
 *
 * <p>Submitted tasks have a happens-before order as defined in the Java Language Specification.
 * Tasks execute with the same happens-before order that the function calls to {@link #submit} and
 * {@link #submitAsync} that submitted those tasks had.
 *
 * <p>This class has limited support for cancellation and other "early completions":
 *
 * <ul>

Par défaut, **FastAPI** convertirait automatiquement cette valeur de retour en JSON en utilisant le `jsonable_encoder` expliqué dans [JSON Compatible Encoder](../tutorial/encoder.md){.internal-link target=_blank}.

Ensuite, en arrière-plan, il mettra ces données JSON-compatible (par exemple un `dict`) à l'intérieur d'un `JSONResponse` qui sera utilisé pour envoyer la réponse au client.

 *
 * <p>Each request is associated with a {@link ProtoSession} that contains the configuration
 * and context necessary for request processing, including:
 * <ul>
 *   <li>User and system properties for interpolation</li>
 *   <li>Session start time information</li>
 *   <li>Project directory structures</li>
 * </ul>
 *
 * <p>Requests can optionally carry trace information through {@link RequestTrace} to support:
 * <ul>

       <title>Incubating APIs</title>
       <link xmlns:xslthl="http://xslthl.sf.net" rel="stylesheet" href="https://fonts.googleapis.com/css?family=Lato:400,400i,700">
       <meta xmlns:xslthl="http://xslthl.sf.net" content="width=device-width, initial-scale=1" name="viewport">

   * given value. If multiple parameters with the same attributes are necessary use {@link
   * #withParameters(String, Iterable)}. Prefer {@link #withCharset} for setting the {@code charset}
   * parameter when using a {@link Charset} object.
   *
   * @throws IllegalArgumentException if either {@code attribute} or {@code value} is invalid
   */

  /**
   * An instance created in {@link #readObject} to be returned from {@link #readResolve}. This field
   * is used only by those methods, and it is never set in a "normal" instance.
   *
   * <p>This class needs to write deserialized data into fields that are {@code final transient}.
   * Such writes will become impossible to perform in {@link #readObject} after JEP 500. Instead, we

本例没有实现回调本身（只是一行代码），只有文档部分。

/// tip | 提示

实际的回调只是 HTTP 请求。

实现回调时，要使用 <a href="https://www.encode.io/httpx/" class="external-link" target="_blank">HTTPX</a> 或 <a href="https://requests.readthedocs.io/" class="external-link" target="_blank">Requests</a>。

///

## 编写回调文档代码

应用不执行这部分代码，只是用它来*记录 外部 API* 。

但，您已经知道用 **FastAPI** 创建自动 API 文档有多简单了。

    } else if (superString != null) {
      return resultString + superString;
    }
    return null;
  }

  /**
   * An {@link AbstractTransformFuture} that delegates to an {@link AsyncFunction} and {@link
   * #setFuture(ListenableFuture)}.
   */
  private static final class AsyncTransformFuture<
          I extends @Nullable Object, O extends @Nullable Object>