//// tab | Python 3.10+

```Python hl_lines="26-27  30"
{!> ../../docs_src/dependency_testing/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="28-29  32"
{!> ../../docs_src/dependency_testing/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="29-30  33"

//// 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!}

//// 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!}

        pytest.param("tutorial001_py39", marks=needs_py39),
        pytest.param("tutorial001_py310", marks=needs_py310),
        "tutorial001_an",
        pytest.param("tutorial001_an_py39", marks=needs_py39),
        pytest.param("tutorial001_an_py310", marks=needs_py310),
    ],
)
def get_client(request: pytest.FixtureRequest):
    clear_sqlmodel()
    # TODO: remove when updating SQL tutorial to use new lifespan API

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/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"]