Ele sempre terá os escopos de segurança declarados nas dependências atuais de `Security` e todos os dependentes para **aquela** *operação de rota* **específica** e **aquela** árvore de dependência **específica**.

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}

Esse código declara um parâmetro de consulta opcional, `q`, com o tipo `str`, e então retorna esse parâmetro.

Isso é bastante simples (e não muito útil), mas irá nos ajudar a focar em como as subdependências funcionam.

## Segunda dependência, "injetável" e "dependente"

# Sub-dependencies { #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" { #first-dependency-dependable }

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

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}

**FastAPI** kümmert sich darum, sie aufzulösen.

## Erste Abhängigkeit, „Dependable“

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

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}

Diese deklariert einen optionalen Abfrageparameter `q` vom Typ `str` und gibt ihn dann einfach zurück.

Pueden ser tan **profundas** como necesites.

**FastAPI** se encargará de resolverlas.

## Primera dependencia "dependable"

Podrías crear una primera dependencia ("dependable") así:

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}

Declara un parámetro de query opcional `q` como un `str`, y luego simplemente lo devuelve.

{* ../../docs_src/dependencies/tutorial007.py hl[2:4] *}

O valor gerado (yielded) é o que é injetado nas *operações de rota* e outras dependências.

{* ../../docs_src/dependencies/tutorial007.py hl[4] *}

O código após o `yield` é executado após a resposta ser entregue:

{* ../../docs_src/dependencies/tutorial007.py hl[5:6] *}

/// tip | Dica

# 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()`

# 🌐 🔗

🆎 🈸 👆 💪 💚 🚮 🔗 🎂 🈸.

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

👈 💼, 👫 🔜 ✔ 🌐 *➡ 🛠️* 🈸:

{* ../../docs_src/dependencies/tutorial012.py hl[15] *}

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

## 🔗 👪 *➡ 🛠️*

# Global Dependencies { #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:

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:

{* ../../docs_src/dependencies/tutorial012_an_py39.py hl[16] *}