## Declare model attributes

You can then use `Field` with model attributes:

=== "Python 3.10+"

    ```Python hl_lines="11-14"
    {!> ../../../docs_src/body_fields/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="11-14"
    {!> ../../../docs_src/body_fields/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="12-15"

## 声明模型属性

然后，使用 `Field` 定义模型的属性：

=== "Python 3.10+"

    ```Python hl_lines="11-14"
    {!> ../../../docs_src/body_fields/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="11-14"
    {!> ../../../docs_src/body_fields/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="12-15"

=== "Python 3.9+"

    ```Python hl_lines="10-12"
    {!> ../../../docs_src/request_forms_and_files/tutorial001_an_py39.py!}
    ```

=== "Python 3.6+"

    ```Python hl_lines="9-11"
    {!> ../../../docs_src/request_forms_and_files/tutorial001_an.py!}
    ```

=== "Python 3.6+ без Annotated"

    !!! tip "Подсказка"
        Предпочтительнее использовать версию с аннотацией, если это возможно.

## 모델 어트리뷰트 선언

그 다음 모델 어트리뷰트와 함께 `Field`를 사용할 수 있습니다:

=== "Python 3.10+"

    ```Python hl_lines="11-14"
    {!> ../../../docs_src/body_fields/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="11-14"
    {!> ../../../docs_src/body_fields/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="12-15"

In this example we'll create a temporary database only for the tests.

## File structure

We create a new file at `sql_app/tests/test_sql_app.py`.

So the new file structure looks like:

``` hl_lines="9-11"
.
└── sql_app
    ├── __init__.py
    ├── crud.py
    ├── database.py
    ├── main.py
    ├── models.py
    ├── schemas.py
    └── tests
        ├── __init__.py
        └── test_sql_app.py
```

    {!> ../../../docs_src/dependencies/tutorial005_an.py!}
    ```

=== "Python 3.10 nicht annotiert"

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

    ```Python hl_lines="11"
    {!> ../../../docs_src/dependencies/tutorial005_py310.py!}
    ```

=== "Python 3.8 nicht annotiert"

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

, `0.5` 🔜 ☑ 💲. ✋️ `0.0` ⚖️ `0` 🔜 🚫.

&amp; 🎏 <abbr title="less than"><code>lt</code></abbr>.

```Python hl_lines="11"
{!../../../docs_src/path_params_numeric_validations/tutorial006.py!}
```

## 🌃

=== "Python 3.9+"

    ```Python hl_lines="10-12"
    {!> ../../../docs_src/request_forms_and_files/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="9-11"
    {!> ../../../docs_src/request_forms_and_files/tutorial001_an.py!}
    ```

=== "Python 3.8+ non-Annotated"

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

    ```Python hl_lines="8"

=== "Python 3.9+"

    ```Python hl_lines="12"
    {!> ../../../docs_src/security/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="11"
    {!> ../../../docs_src/security/tutorial001_an.py!}
    ```

=== "Python 3.8+ non-Annotated"

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

    ```Python hl_lines="10"

* 等……

上述场景均可以使用**依赖注入**，将代码重复最小化。

## 第一步

接下来，我们学习一个非常简单的例子，尽管它过于简单，不是很实用。

但通过这个例子，您可以初步了解「依赖注入」的工作机制。

### 创建依赖项

首先，要关注的是依赖项。

依赖项就是一个函数，且可以使用与*路径操作函数*相同的参数：

```Python hl_lines="8-11"
{!../../../docs_src/dependencies/tutorial001.py!}
```

大功告成。

只用了**2 行**代码。

依赖项函数的形式和结构与*路径操作函数*一样。

因此，可以把依赖项当作没有「装饰器」（即，没有 `@app.get("/some-path")` ）的路径操作函数。

依赖项可以返回各种内容。