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。

我们要使用与存档*外部 API* 相同的知识……通过创建外部 API 要实现的*路径操作*（您的 API 要调用的）。

{* ../../docs_src/app_testing/app_b_an_py310/test_main.py *}


Whenever you need the client to pass information in the request and you don't know how to, you can search (Google) how to do it in `httpx`, or even how to do it with `requests`, as HTTPX's design is based on Requests' design.

Then you just do the same in your tests.

E.g.:

* To pass a *path* or *query* parameter, add it to the URL itself.

		Usage:  "idle timeout is the maximum amount of time to wait for the next request when keep-alive are enabled",
		EnvVar: "MINIO_IDLE_TIMEOUT",
		Hidden: true,
	},
	cli.DurationFlag{
		Name:   "read-header-timeout",
		Value:  xhttp.DefaultReadHeaderTimeout,
		Usage:  "read header timeout is the amount of time allowed to read request headers",
		EnvVar: "MINIO_READ_HEADER_TIMEOUT",
		Hidden: true,
	},

- `aws:SecureTransport` - This is a Boolean value that represents whether the request was sent over TLS.
- `aws:SourceIp` - This is the requester's IP address, for use with IP address conditions. If running behind Nginx like proxies, MinIO preserve's the source IP.

```
{
  "Version": "2012-10-17",
  "Statement": {
	"Effect": "Allow",

* **Chequeo de tipos**.

...y **FastAPI** usa las mismas declaraciones para:

* **Definir requerimientos**: de parámetros de path de la request, parámetros de query, headers, bodies, dependencias, etc.
* **Convertir datos**: de la request al tipo requerido.
* **Validar datos**: provenientes de cada request:
    * Generando **errores automáticos** devueltos al cliente cuando los datos son inválidos.
* **Documentar** la API usando OpenAPI:

import org.apache.maven.api.annotations.Immutable;
import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.annotations.NotThreadSafe;
import org.apache.maven.api.annotations.Nullable;

/**
 * An XML reader request.
 *
 * @since 4.0.0
 */
@Experimental
@Immutable
public interface XmlReaderRequest {

    @Nullable
    Path getPath();

    @Nullable
    Path getRootDirectory();

    @Nullable

### CORS-запросы с предварительной проверкой { #cors-preflight-requests }

Это любые `OPTIONS`-запросы с заголовками `Origin` и `Access-Control-Request-Method`.

В этом случае middleware перехватит входящий запрос и отправит соответствующие CORS-заголовки в ответе, а также ответ `200` или `400` в информационных целях.

### Простые запросы { #simple-requests }

Al construir APIs web con FastAPI, si hay un error en nuestro código, FastAPI normalmente lo contiene al request único que desencadenó el error. 🛡

El cliente obtendrá un **500 Internal Server Error** para ese request, pero la aplicación continuará funcionando para los siguientes requests en lugar de simplemente colapsar por completo.

### Errores Mayores - Colapsos { #bigger-errors-crashes }

Notice that we declare the type of `current_user` as the Pydantic model `User`.

This will help us inside of the function with all the completion and type checks.

/// tip

You might remember that request bodies are also declared with Pydantic models.

Here **FastAPI** won't get confused because you are using `Depends`.

///

/// check

                        "While this /may/ work fine, please look for plugin updates and/or "
                                + "request plugins be made thread-safe.",
                        "If reporting an issue, report it against the plugin in question, not against Apache Maven.")) {
                    logger.warn(s);
                }