# Dependencies - `Depends()` and `Security()`

## `Depends()`

Dependencies are handled mainly with the special function `Depends()` that takes a callable.

Here is the reference for it and its parameters.

You can import it directly from `fastapi`:

```python
from fastapi import Depends
```

::: fastapi.Depends

## `Security()`

Para fazer isso, nós declaramos o método `__call__`:

//// tab | Python 3.9+

```Python hl_lines="12"
{!> ../../docs_src/dependencies/tutorial011_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="11"
{!> ../../docs_src/dependencies/tutorial011_an.py!}
```

////

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

/// tip | "Dica"

# Sub-dependencies

You can create dependencies that have **sub-dependencies**.

They can be as **deep** as you need them to be.

**FastAPI** will take care of solving them.

## First dependency "dependable"

You could create a first dependency ("dependable") like:

//// tab | Python 3.10+

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

////

//// tab | Python 3.9+

Подобно тому, как вы можете [добавлять зависимости через параметр `dependencies` в *декораторах операций пути*](dependencies-in-path-operation-decorators.md){.internal-link target=_blank}, вы можете добавлять зависимости сразу ко всему `FastAPI` приложению.

В этом случае они будут применяться ко всем *операциям пути* в приложении:

//// tab | Python 3.9+

```Python hl_lines="16"
{!> ../../docs_src/dependencies/tutorial012_an_py39.py!}
```

////

De forma semelhante a [adicionar dependências (`dependencies`) em *decoradores de operação de rota*](dependencies-in-path-operation-decorators.md){.internal-link target=_blank}, você pode adicioná-las à aplicação `FastAPI`.

Nesse caso, elas serão aplicadas a todas as *operações de rota* da aplicação:

//// tab | Python 3.9+

```Python hl_lines="16"
{!> ../../docs_src/dependencies/tutorial012_an_py39.py!}
```

////

# 🌐 🔗

🆎 🈸 👆 💪 💚 🚮 🔗 🎂 🈸.

🎏 🌌 👆 💪 [🚮 `dependencies` *➡ 🛠️ 👨‍🎨*](dependencies-in-path-operation-decorators.md){.internal-link target=_blank}, 👆 💪 🚮 👫 `FastAPI` 🈸.

👈 💼, 👫 🔜 ✔ 🌐 *➡ 🛠️* 🈸:

```Python hl_lines="15"
{!../../docs_src/dependencies/tutorial012.py!}
```

& 🌐 💭 📄 🔃 [❎ `dependencies` *➡ 🛠️ 👨‍🎨*](dependencies-in-path-operation-decorators.md){.internal-link target=_blank} ✔, ✋️ 👉 💼, 🌐 *➡ 🛠️* 📱.

# Global Dependencies

For some types of applications you might want to add dependencies to the whole application.

Similar to the way you can [add `dependencies` to the *path operation decorators*](dependencies-in-path-operation-decorators.md){.internal-link target=_blank}, you can add them to the `FastAPI` application.

In that case, they will be applied to all the *path operations* in the application:

//// tab | Python 3.9+

```Python hl_lines="16"

Ähnlich wie Sie [`dependencies` zu den *Pfadoperation-Dekoratoren* hinzufügen](dependencies-in-path-operation-decorators.md){.internal-link target=_blank} können, können Sie sie auch zur `FastAPI`-Anwendung hinzufügen.

In diesem Fall werden sie auf alle *Pfadoperationen* in der Anwendung angewendet:

//// tab | Python 3.9+

```Python hl_lines="16"
{!> ../../docs_src/dependencies/tutorial012_an_py39.py!}
```

////

//// 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!}
```

////

//// tab | Python 3.10 nicht annotiert

这里说的不是类本身（类本就是可调用项），而是类实例。

为此，需要声明 `__call__` 方法：

```Python hl_lines="10"
{!../../docs_src/dependencies/tutorial011.py!}
```

本例中，**FastAPI**  使用 `__call__` 检查附加参数及子依赖项，稍后，还要调用它向*路径操作函数*传递值。

## 参数化实例

接下来，使用 `__init__` 声明用于**参数化**依赖项的实例参数：

```Python hl_lines="7"
{!../../docs_src/dependencies/tutorial011.py!}
```

本例中，**FastAPI** 不使用 `__init__`，我们要直接在代码中使用。

## 创建实例

使用以下代码创建类实例：