你还可以通过将默认值设置为 `None` 来将请求体参数声明为可选参数：

//// tab | Python 3.10+

```Python hl_lines="18-20"
{!> ../../docs_src/body_multiple_params/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="18-20"
{!> ../../docs_src/body_multiple_params/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="19-21"
{!> ../../docs_src/body_multiple_params/tutorial001_an.py!}

我们建议使用 **FastAPI** 的安全工具。

## 概览

首先，看看下面的代码是怎么运行的，然后再回过头来了解其背后的原理。

## 创建 `main.py`

把下面的示例代码复制到 `main.py`：

//// tab | Python 3.9+

```Python
{!> ../../docs_src/security/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python
{!> ../../docs_src/security/tutorial001_an.py!}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip

{* ../../docs_src/path_params_numeric_validations/tutorial003_an_py39.py hl[10] *}

## Validations numériques : supérieur ou égal

Avec `Query` et `Path` (et d'autres que vous verrez plus tard) vous pouvez déclarer des contraintes numériques.

Ici, avec `ge=1`, `item_id` devra être un nombre entier "`g`reater than or `e`qual" à `1`.

{* ../../docs_src/path_params_numeric_validations/tutorial004_an_py39.py hl[10] *}

{!> ../../docs_src/query_params_str_validations/tutorial003_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="10"
{!> ../../docs_src/query_params_str_validations/tutorial003_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="11"
{!> ../../docs_src/query_params_str_validations/tutorial003_an.py!}
```

////

{!> ../../docs_src/query_params_str_validations/tutorial003_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="10"
{!> ../../docs_src/query_params_str_validations/tutorial003_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="11"
{!> ../../docs_src/query_params_str_validations/tutorial003_an.py!}
```

////

{!> ../../docs_src/query_params_str_validations/tutorial003_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="10"
{!> ../../docs_src/query_params_str_validations/tutorial003_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="11"
{!> ../../docs_src/query_params_str_validations/tutorial003_an.py!}
```

////

"docs_src/dependencies/tutorial008_an.py" = ["F821"]
"docs_src/dependencies/tutorial008_an_py39.py" = ["F821"]
"docs_src/query_params_str_validations/tutorial012_an.py" = ["B006"]
"docs_src/query_params_str_validations/tutorial012_an_py39.py" = ["B006"]
"docs_src/query_params_str_validations/tutorial013_an.py" = ["B006"]
"docs_src/query_params_str_validations/tutorial013_an_py39.py" = ["B006"]
"docs_src/security/tutorial004.py" = ["B904"]

* 在*路径操作*的依赖项中使用 `security`
* 返回类型为 `HTTPBasicCredentials` 的对象：
    * 包含发送的 `username` 与 `password`

//// tab | Python 3.9+

```Python hl_lines="4  8  12"
{!> ../../docs_src/security/tutorial006_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="2  7  11"
{!> ../../docs_src/security/tutorial006_an.py!}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip

Sebastián Ramírez <******@****.***> 1679142599 +0100

Sebastián Ramírez <******@****.***> 1679142599 +0100