## OpenAPI 客户端生成

有许多工具可以从**OpenAPI**生成客户端。

一个常见的工具是 <a href="https://openapi-generator.tech/" class="external-link" target="_blank">OpenAPI Generator</a>。

如果您正在开发**前端**，一个非常有趣的替代方案是 <a href="https://github.com/hey-api/openapi-ts" class="external-link" target="_blank">openapi-ts</a>。

## 生成一个 TypeScript 前端客户端

让我们从一个简单的 FastAPI 应用开始：

//// tab | Python 3.9+

```Python hl_lines="7"
{!../../docs_src/query_params_str_validations/tutorial006b.py!}
```

/// info

如果你之前没见过 `...` 这种用法：它是一个特殊的单独值，它是 <a href="https://docs.python.org/3/library/constants.html#Ellipsis" class="external-link" target="_blank">Python 的一部分并且被称为「省略号」</a>。
Pydantic 和 FastAPI 使用它来显式的声明需要一个值。

///

这将使 **FastAPI** 知道此查询参数是必需的。

### 使用`None`声明必需参数

你可以声明一个参数可以接收`None`值，但它仍然是必需的。这将强制客户端发送一个值，即使该值是`None`。

)
```

/// info | Informação

Para uma explicação mais completa de `**user_dict`, verifique [a documentação para **Extra Models**](../extra-models.md#about-user_indict){.internal-link target=_blank}.

///

## Retorne o token

A resposta do endpoint `token` deve ser um objeto JSON.

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"Strong"};c&&a.extend(d,c),b.bind("keyup",function(){var b=a(this).val(),c="undefined"==typeof d.parent?a(this).parent():a(d.parent),e=c.find(".strength-meter"),f=a.formUtils.validators.validate_strength.calculatePasswordStrength(b),g={background:"pink",color:"#FF0000",fontWeight:"bold",border:"red solid 1px",borderWidth:"0px 0px 4px",display:"inline-block",fontSize:d.fontSize,padding:d.padding},h=d.bad;0===e.length&&(e=a("<span></span>"),e.addClass("strength-meter").appendTo(c)),b?e.show():e.hi...

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