$ pip install websockets

---> 100%
```

</div>

## WebSockets client

### In production

In your production system, you probably have a frontend created with a modern framework like React, Vue.js or Angular.

And to communicate using WebSockets with your backend you would probably use your frontend's utilities.

Or you might have a native mobile application that communicates with your WebSocket backend directly, in native code.

## 安装 `WebSockets`

首先，您需要安装 `WebSockets`：

```console
$ pip install websockets

---> 100%
```

## WebSockets 客户端

### 在生产环境中

在您的生产系统中，您可能使用现代框架（如React、Vue.js或Angular）创建了一个前端。

要使用 WebSockets 与后端进行通信，您可能会使用前端的工具。

或者，您可能有一个原生移动应用程序，直接使用原生代码与 WebSocket 后端通信。

或者，您可能有其他与 WebSocket 终端通信的方式。

---

但是，在本示例中，我们将使用一个非常简单的HTML文档，其中包含一些JavaScript，全部放在一个长字符串中。

まず `WebSockets`のインストールが必要です。

<div class="termy">

```console
$ pip install websockets

---> 100%
```

</div>

## WebSocket クライアント

### 本番環境

本番環境では、React、Vue.js、Angularなどの最新のフレームワークで作成されたフロントエンドを使用しているでしょう。

そして、バックエンドとWebSocketを使用して通信するために、おそらくフロントエンドのユーティリティを使用することになるでしょう。

または、ネイティブコードでWebSocketバックエンドと直接通信するネイティブモバイルアプリケーションがあるかもしれません。

他にも、WebSocketのエンドポイントと通信する方法があるかもしれません。

7. Here the `response_model` is using a type annotation of a list of `Author` dataclasses.

    Again, you can combine `dataclasses` with standard type annotations.

8. Notice that this *path operation function* uses regular `def` instead of `async def`.

    As always, in FastAPI you can combine `def` and `async def` as needed.

### Step 5: return the content

```Python hl_lines="8"
{!../../../docs_src/first_steps/tutorial001.py!}
```

You can return a `dict`, `list`, singular values as `str`, `int`, etc.

You can also return Pydantic models (you'll see more about that later).

    ```

=== "🐍 3️⃣.1️⃣0️⃣ & 🔛"

    ```Python hl_lines="7"
    {!> ../../../docs_src/query_params_str_validations/tutorial003_py310.py!}
    ```

## 🚮 🥔 🧬

👆 💪 🔬 <abbr title="A regular expression, regex or regexp is a sequence of characters that define a search pattern for strings.">🥔 🧬</abbr> 👈 🔢 🔜 🏏:

=== "🐍 3️⃣.6️⃣ &amp; 🔛"

    ```Python hl_lines="11"

            """
        ),
    ] = True,
) -> Any:
    """
    Declare a FastAPI Security dependency.

    The only difference with a regular dependency is that it can declare OAuth2
    scopes that will be integrated with OpenAPI and the automatic UI docs (by default
    at `/docs`).

    It takes a single "dependable" callable (like a function).

## Singular values in body

The same way there is a `Query` and `Path` to define extra data for query and path parameters, **FastAPI** provides an equivalent `Body`.

For example, extending the previous model, you could decide that you want to have another key `importance` in the same body, besides the `item` and `user`.

Você pode definir uma <abbr title="Uma expressão regular, regex ou regexp é uma sequência de caracteres que define um parâmetro de busca para textos.">expressão regular</abbr> que combine com um padrão esperado pelo parâmetro:

```Python hl_lines="11"
{!../../../docs_src/query_params_str_validations/tutorial004.py!}
```

Essa expressão regular específica verifica se o valor recebido no parâmetro:

That means: "the variable `items` is a `list`, and each of the items in this list is a `str`".

!!! tip
    If you use Python 3.9 or above, you don't have to import `List` from `typing`, you can use the same regular `list` type instead.

By doing that, your editor can provide support even while processing items from the list:

<img src="/img/python-types/image05.png">

Without types, that's almost impossible to achieve.