## Import `Header`

First import `Header`:

=== "Python 3.10+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/header_params/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/header_params/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/header_params/tutorial001_an.py!}

=== "Python 3.9+"

    ```Python hl_lines="9"
    {!> ../../../docs_src/request_files/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="8"
    {!> ../../../docs_src/request_files/tutorial001_an.py!}
    ```

=== "Python 3.8+ nicht annotiert"

    !!! tip "Tipp"
        Bevorzugen Sie die `Annotated`-Version, falls möglich.

    ```Python hl_lines="7"

但这并不是声明依赖项的唯一方法(尽管它可能是更常见的方法)。

关键因素是依赖项应该是 "可调用对象"。

Python 中的 "**可调用对象**" 是指任何 Python 可以像函数一样 "调用" 的对象。

所以，如果你有一个对象 `something` (可能*不是*一个函数)，你可以 "调用" 它(执行它)，就像：

```Python
something()
```

或者

```Python
something(some_argument, some_keyword_argument="foo")
```

这就是 "可调用对象"。

## 类作为依赖项

您可能会注意到，要创建一个 Python 类的实例，您可以使用相同的语法。

举个例子:

```Python
class Cat:
    def __init__(self, name: str):

    ```

=== "Python 3.9+"

    ```Python hl_lines="5  12-16"
    {!> ../../../docs_src/security/tutorial002_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="5  13-17"
    {!> ../../../docs_src/security/tutorial002_an.py!}
    ```

=== "Python 3.10+ non-Annotated"

    !!! tip
        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="3  10-14"

=== "Python 3.10+"

    ```Python hl_lines="1  3"
    {!> ../../../docs_src/path_params_numeric_validations/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="1  3"
    {!> ../../../docs_src/path_params_numeric_validations/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="3-4"

=== "Python 3.10+"

    ```Python hl_lines="1  3  12-16"
    {!> ../../../docs_src/extra_data_types/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="1  3  12-16"
    {!> ../../../docs_src/extra_data_types/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="1  3  13-17"

## 例子

下面是一个*路径操作*的示例，其中的参数使用了上面的一些类型。

=== "Python 3.10+"

    ```Python hl_lines="1  3  12-16"
    {!> ../../../docs_src/extra_data_types/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="1  3  12-16"
    {!> ../../../docs_src/extra_data_types/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="1  3  13-17"

Sie könnten eine erste Abhängigkeit („Dependable“) wie folgt erstellen:

=== "Python 3.10+"

    ```Python hl_lines="8-9"
    {!> ../../../docs_src/dependencies/tutorial005_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="8-9"
    {!> ../../../docs_src/dependencies/tutorial005_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="9-10"
    {!> ../../../docs_src/dependencies/tutorial005_an.py!}

=== "Python 3.10+"

    ```Python hl_lines="1  14-15  18-20  33"
    {!> ../../../docs_src/extra_models/tutorial003_py310.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="1  14-15  18-20  33"
    {!> ../../../docs_src/extra_models/tutorial003.py!}
    ```

## 模型列表

使用同样的方式也可以声明由对象列表构成的响应。

为此，请使用标准的 Python `typing.List`：

=== "Python 3.9+"

    ```Python hl_lines="18"

У нас была аннотация следующего типа:

=== "Python 3.10+"

    ```Python
    q: str | None = None
    ```

=== "Python 3.8+"

    ```Python
    q: Union[str, None] = None
    ```

Вот что мы получим, если обернём это в `Annotated`:

=== "Python 3.10+"

    ```Python
    q: Annotated[str | None] = None
    ```

=== "Python 3.8+"

    ```Python
    q: Annotated[Union[str, None]] = None