`@ParametersAreNonnullByDefault` and all parameters and return types are
    never null unless explicitly annotated `@Nullable`.

 *  **Warning: this release is source-incompatible for Kotlin users.**
    Nullability was previously ambiguous and lenient but now the compiler will
    enforce strict null checks.

 *  New: The response message is now non-null. This is the "Not Found" in the

 *   <li>Events for the different listeners are dispatched concurrently.
 *   <li>All events for a given listener dispatch on the provided executor.
 *   <li>It is easy for the user to ensure that listeners are never invoked while holding locks.
 * </ul>
 *
 * The last point is subtle. Often the observable object will be managing its own internal state

{* ../../docs_src/extra_models/tutorial001_py310.py hl[7,9,14,20,22,27:28,31:33,38:39] *}

### Про `**user_in.model_dump()` { #about-user-in-model-dump }

#### `.model_dump()` из Pydantic { #pydantics-model-dump }

`user_in` — это Pydantic-модель класса `UserIn`.

У Pydantic-моделей есть метод `.model_dump()`, который возвращает `dict` с данными модели.

{* ../../docs_src/extra_models/tutorial001_py310.py hl[7,9,14,20,22,27:28,31:33,38:39] *}

### Sobre `**user_in.model_dump()` { #about-user-in-model-dump }

#### O `.model_dump()` do Pydantic { #pydantics-model-dump }

`user_in` é um modelo Pydantic da classe `UserIn`.

    /**
     * The media-type multipart/form-data follows the rules of all multipart MIME data streams as
     * outlined in RFC 2046. In forms, there are a series of fields to be supplied by the user who
     * fills out the form. Each field has a name. Within a given form, the names are unique.
     */
    @JvmField
    val FORM = "multipart/form-data".toMediaType()

 *
 * <p>A discrete domain always represents the <i>entire</i> set of values of its type; it cannot
 * represent partial domains such as "prime integers" or "strings of length 5."
 *
 * <p>See the Guava User Guide section on <a href=
 * "https://github.com/google/guava/wiki/RangesExplained#discrete-domains">{@code
 * DiscreteDomain}</a>.
 *
 * @author Kevin Bourrillion
 * @since 10.0
 */

             Searching for package file structure from directories with
             <font color="#3465A4">__init__.py</font> files
             Importing from <font color="#75507B">/home/user/code/</font><font color="#AD7FA8">awesomeapp</font>

   <span style="background-color:#007166"><font color="#D3D7CF"> module </font></span>  🐍 main.py

             Searching for package file structure from directories with
             <font color="#3465A4">__init__.py</font> files
             Importing from <font color="#75507B">/home/user/code/</font><font color="#AD7FA8">awesomeapp</font>

   <span style="background-color:#007166"><font color="#D3D7CF"> module </font></span>  🐍 main.py

             Searching for package file structure from directories
             with <font color="#3465A4">__init__.py</font> files
             Importing from <font color="#75507B">/home/user/code/</font><font color="#AD7FA8">awesomeapp</font>

   <span style="background-color:#007166"><font color="#D3D7CF"> module </font></span>  🐍 main.py

* 把接收的数据赋值给参数 `item`。
    * 因为你把函数中的参数类型声明为 `Item`，所以还能获得所有属性及其类型的编辑器支持（补全等）。
* 为你的模型生成 [JSON Schema](https://json-schema.org) 定义，如果对你的项目有意义，还可以在其他地方使用它们。
* 这些 schema 会成为生成的 OpenAPI Schema 的一部分，并被自动文档的 <abbr title="User Interfaces - 用户界面">UIs</abbr> 使用。

## 自动文档 { #automatic-docs }

你的模型的 JSON Schema 会成为生成的 OpenAPI Schema 的一部分，并显示在交互式 API 文档中：

<img src="/img/tutorial/body/image01.png">

并且，还会用于需要它们的每个*路径操作*的 API 文档中：