```

En algunos casos, incluso es posible tener modelos de Pydantic v1 y v2 en la misma **path operation** de tu app de FastAPI:

{* ../../docs_src/pydantic_v1_in_v2/tutorial003_an_py310.py hl[2:3,6,12,21:22] *}

En el ejemplo anterior, el modelo de entrada es un modelo de Pydantic v1 y el modelo de salida (definido en `response_model=ItemV2`) es un modelo de Pydantic v2.

### Parámetros de Pydantic v1 { #pydantic-v1-parameters }

     *
     * The key idea is that based on the number of leading zeros (equivalently, floor(log2(x))), we
     * can narrow the possible floor(log10(x)) values to two. For example, if floor(log2(x)) is 6,
     * then 64 <= x < 128, so floor(log10(x)) is either 1 or 2.
     */
    int y = maxLog10ForLeadingZeros[Integer.numberOfLeadingZeros(x)];
    /*

     * might not run some of its listeners. The likely result is that the app will hang. (And of
     * course stack overflows are bad news in general. For example, we may have overflowed in the
     * middle of defining a class. If so, that class will never be loadable in this process.) The
     * best we can do (since logging may overflow the stack) is to let the error propagate. Because

 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingMultiset} forward <b>indiscriminately</b> to
 * the methods of the delegate. For example, overriding {@link #add(Object, int)} alone <b>will
 * not</b> change the behavior of {@link #add(Object)}, which can lead to unexpected behavior. In

 * It can identify areas where string deduplication could provide significant memory savings.</p>
 *
 * <p>Usage example:</p>
 * <pre>
 * PomMemoryAnalyzer analyzer = new PomMemoryAnalyzer();
 * Model model = reader.read(Files.newInputStream(pomPath));
 * analyzer.analyzePom(model);
 * analyzer.printAnalysis();
 * </pre>
 *

             * plugins that require dependency resolution, although they usually run in phases of the build where project
             * artifacts haven't been assembled yet. The prime example of this is "mvn release:prepare".
             */
            if (aggregating && areAllDependenciesInReactor(session.getProjects(), result.getUnresolvedDependencies())) {

此处唯一比较新的内容是*路径操作装饰器*中的 `callbacks=invoices_callback_router.routes` 参数，下文介绍。

## 存档回调 { #documenting-the-callback }

实际的回调代码高度依赖于您自己的 API 应用。

并且可能每个应用都各不相同。

回调代码可能只有一两行，比如：

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

但回调最重要的部分可能是，根据 API 要发送给回调请求体的数据等内容，确保您的 API 用户（外部开发者）正确地实现*外部 API*。

		writeTimeout        time.Duration
		expectedListenErrs  []bool
	}{
		{[]string{"93.184.216.34:65432"}, time.Duration(0), time.Duration(0), time.Duration(0), []bool{true}},                           // 1
		{[]string{"example.org:65432"}, time.Duration(0), time.Duration(0), time.Duration(0), []bool{true}},                             // 2

 * FluentFuture.transform}), but you will often find it easier to use a framework. Frameworks
 * automate the process, often adding features like monitoring, debugging, and cancellation.
 * Examples of frameworks include:
 *
 * <ul>
 *   <li><a href="https://dagger.dev/producers.html">Dagger Producers</a>
 * </ul>
 *
 * <p>The main purpose of {@link #addListener addListener} is to support this chaining. You will

 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingNavigableMap} forward <i>indiscriminately</i>
 * to the methods of the delegate. For example, overriding {@link #put} alone <i>will not</i> change
 * the behavior of {@link #putAll}, which can lead to unexpected behavior. In this case, you should