Использование Linux-контейнеров даёт ряд преимуществ: **безопасность**, **воспроизводимость**, **простоту** и другие.

/// tip | Подсказка

Нет времени и вы уже знакомы с этим? Перейдите к [`Dockerfile` ниже 👇](#build-a-docker-image-for-fastapi).

///

<details>
<summary>Предпросмотр Dockerfile 👀</summary>

```Dockerfile

```

...and pass whatever that returns as the value of the dependency in our *path operation function* as the parameter `fixed_content_included`:

{* ../../docs_src/dependencies/tutorial011_an_py39.py hl[22] *}

/// tip

All this might seem contrived. And it might not be very clear how is it useful yet.

These examples are intentionally simple, but show how it all works.

Вы можете задать `schema_extra` со `dict`, содержащим любые дополнительные данные, которые вы хотите видеть в сгенерированной JSON Schema, включая `examples`.

////

/// tip | Подсказка

Вы можете использовать тот же приём, чтобы расширить JSON Schema и добавить свою собственную дополнительную информацию.

But in those cases with really bad errors that crash the running **process**, you would want an external component that is in charge of **restarting** the process, at least a couple of times...

/// tip

...Although if the whole application is just **crashing immediately** it probably doesn't make sense to keep restarting it forever. But in those cases, you will probably notice it during development, or at least right after deployment.

/// info | Información

`Form` es una clase que hereda directamente de `Body`.

///

/// tip | Consejo

Para declarar bodies de formularios, necesitas usar `Form` explícitamente, porque sin él, los parámetros se interpretarían como parámetros de query o como parámetros de body (JSON).

///

These dependencies will be executed/solved the same way as normal dependencies. But their value (if they return any) won't be passed to your *path operation function*.

/// tip

Some editors check for unused function parameters, and show them as errors.

Using these `dependencies` in the *path operation decorator* you can make sure they are executed while avoiding editor/tooling errors.

/// info

`Form` is a class that inherits directly from `Body`.

///

/// tip

To declare form bodies, you need to use `Form` explicitly, because without it the parameters would be interpreted as query parameters or body (JSON) parameters.

///

## About "Form Fields" { #about-form-fields }

Это позволит вам **переиспользовать модель** в **разных местах**, а также объявить проверки и метаданные сразу для всех параметров. 😎

/// note | Заметка

Этот функционал доступен с версии `0.115.0`. 🤓

///

/// tip | Совет

Такой же подход применяется для `Query`, `Cookie`, и `Header`. 😎

///

## Pydantic-модель для cookies { #cookies-with-a-pydantic-model }

{!../../docs_src/events/tutorial003.py!}
```

在这里，我们在 `yield` 之前将（虚拟的）模型函数放入机器学习模型的字典中，以此模拟加载模型的耗时**启动**操作。这段代码将在应用程序**开始处理请求之前**执行，即**启动**期间。

然后，在 `yield` 之后，我们卸载模型。这段代码将会在应用程序**完成处理请求后**执行，即在**关闭**之前。这可以释放诸如内存或 GPU 之类的资源。

/// tip | 提示

**关闭**事件只会在你停止应用时触发。

可能你需要启动一个新版本，或者你只是你厌倦了运行它。 🤷

///

## 生命周期函数

首先要注意的是，我们定义了一个带有 `yield` 的异步函数。这与带有 `yield` 的依赖项非常相似。

```Python hl_lines="14-19"

Before FastAPI 0.108.0, Starlette 0.29.0, the `name` was the first parameter.

Also, before that, in previous versions, the `request` object was passed as part of the key-value pairs in the context for Jinja2.

///

/// tip

By declaring `response_class=HTMLResponse` the docs UI will be able to know that the response will be HTML.

///

/// note | Technical Details

You could also use `from starlette.templating import Jinja2Templates`.