因此，我们下一步要做的就是添加代码，为从 API 接收回调的*外部 API*存档。

这部分文档在 `/docs` 下的 Swagger API 文档中显示，并且会告诉外部开发者如何构建*外部 API*。

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* 。

They have proven to be **FastAPI Experts** by helping many others. ✨

/// tip

You could become an official FastAPI Expert too!

Just [help others with questions in GitHub](help-fastapi.md#help-others-with-questions-in-github){.internal-link target=_blank}. 🤓

///

You can see the **FastAPI Experts** for:

/**
 * Testing utilities relating to garbage collection finalization.
 *
 * <p>Use this class to test code triggered by finalization, that is, one of the following
 * actions taken by the java garbage collection system:
 *
 * <ul>
 *   <li>invoking the {@code finalize} methods of unreachable objects
 *   <li>clearing weak references to unreachable referents

Het hele **FastAPI** framework is daarop gebaseerd. Automatische code aanvulling werkt overal.

Je hoeft zelden terug te vallen op de documentatie.

Zo kan je editor je helpen:

* in <a href="https://code.visualstudio.com/" class="external-link" target="_blank">Visual Studio Code</a>:

![editor ondersteuning](https://fastapi.tiangolo.com/img/vscode-completion.png)

  // +optional
  optional string type = 1;

  // Rolling update config params. Present only if type = "RollingUpdate".
  // ---
  // TODO: Update this to follow our convention for oneOf, whatever we decide it
  // to be. Same as Deployment `strategy.rollingUpdate`.
  // See https://github.com/kubernetes/kubernetes/issues/35345
  // +optional
  optional RollingUpdateDaemonSet rollingUpdate = 2;
}

     * an object type argument, since in reflection
     * primitive type arguments are represented by
     * their object counterparts, so for an argument of
     * type (say) java.lang.Integer, it will not be able
     * to decide between a method that takes int and a
     * method that takes java.lang.Integer as a parameter.
     * <p>
     * This turns out to be a relatively rare case
     * where this is needed - however, functionality

var _ Tagger = ETag{} // compiler check

// ETag returns the ETag itself.
//
// By providing this method ETag implements
// the Tagger interface.
func (e ETag) ETag() ETag { return e }

// FromContentMD5 decodes and returns the Content-MD5
// as ETag, if set. If no Content-MD5 header is set
// it returns an empty ETag and no error.
func FromContentMD5(h http.Header) (ETag, error) {
	v, ok := h["Content-Md5"]
	if !ok {

            throwValidationError(messages -> messages.addErrorsCrudCouldNotFindCrudTable(GLOBAL, form.id), this::asEditHtml);
        });
        return redirectWith(getClass(), moreUrl("search").params("q", URLUtil.encode(form.q, Constants.UTF_8)));
    }

    // ===================================================================================
    //                                                                       Validation

    private ASN1ObjectIdentifier selectedMech;
    private ASN1ObjectIdentifier[] remoteMechs;

    private boolean disableMic;
    private boolean requireMic;


    /**
     * Instance a <code>SpnegoContext</code> object by wrapping a {@link SSPContext}
     * with the same mechanism this {@link SSPContext} used.
     * 
     * @param source
     *            the {@link SSPContext} to be wrapped
     */

Sie werden selten noch mal in der Dokumentation nachschauen müssen.

So kann ihr Editor Sie unterstützen:

* in <a href="https://code.visualstudio.com/" class="external-link" target="_blank">Visual Studio Code</a>:

![Editor Unterstützung](https://fastapi.tiangolo.com/img/vscode-completion.png)

* in <a href="https://www.jetbrains.com/pycharm/" class="external-link" target="_blank">PyCharm</a>: