Você pode criar uma primeira dependência (injetável) dessa forma:

//// tab | Python 3.10+

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

////

//// tab | Python 3.9+

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

////

//// tab | Python 3.8+

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

比如，你可以将请求体的一个 `example` 传递给 `Body`:

//// tab | Python 3.10+

```Python hl_lines="22-27"
{!> ../../docs_src/schema_extra_example/tutorial003_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="22-27"
{!> ../../docs_src/schema_extra_example/tutorial003_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="23-28"

</div>

////

### Lendo variáveis de ambiente com Python

Você também pode criar variáveis de ambiente fora do Python, no terminal (ou com qualquer outro método), e realizar a leitura delas no Python.

Por exemplo, você pode definir um arquivo `main.py` com o seguinte código:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// dica

//// tab | Python 3.9+

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

////

//// tab | Python 3.8+

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

////

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

/// tip

Prefer to use the `Annotated` version if possible.

///

```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):

import sys

import pytest
from fastapi._compat import PYDANTIC_V2

needs_py39 = pytest.mark.skipif(sys.version_info < (3, 9), reason="requires python3.9+")
needs_py310 = pytest.mark.skipif(
    sys.version_info < (3, 10), reason="requires python3.10+"
)
needs_pydanticv2 = pytest.mark.skipif(not PYDANTIC_V2, reason="requires Pydantic v2")

```

</div>

////

## Чтение переменных окружения в python

Так же существует возможность создания переменных окружения **вне** Python, в терминале (или любым другим способом), а затем **чтения их в Python**.

Например, у вас есть файл `main.py`:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip

## Пример

Вот пример *операции пути* с параметрами, который демонстрирует некоторые из вышеперечисленных типов.

//// tab | Python 3.8 и выше

```Python hl_lines="1  3  12-16"
{!> ../../docs_src/extra_data_types/tutorial001.py!}
```

////

//// tab | Python 3.10 и выше

```Python hl_lines="1  2  11-15"
{!> ../../docs_src/extra_data_types/tutorial001_py310.py!}
```

////

## Importe `Cookie`

Primeiro importe `Cookie`:

//// tab | Python 3.10+

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

////

//// tab | Python 3.9+

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

////

//// tab | Python 3.8+

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

//// tab | Python 3.9+

```Python hl_lines="9"
{!> ../../docs_src/dependencies/tutorial011_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="8"
{!> ../../docs_src/dependencies/tutorial011_an.py!}
```

////

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

/// tip

Prefer to use the `Annotated` version if possible.