### Dependências { #dependencies }

O mesmo se aplica para as [dependências](tutorial/dependencies/index.md). Se uma dependência tem as funções com padrão `def` ao invés de `async def`, ela é rodada no threadpool externo.

### Sub-dependências { #sub-dependencies }

Se você quiser instalar o FastAPI com as dependências padrão, mas sem o `fastapi-cloud-cli`, você pode instalar com `pip install "fastapi[standard-no-fastapi-cloud-cli]"`.

### Dependências opcionais adicionais { #additional-optional-dependencies }

Existem algumas dependências adicionais que você pode querer instalar.

Dependências opcionais adicionais do Pydantic:

### Dependencias { #dependencies }

Lo mismo aplica para las [dependencias](tutorial/dependencies/index.md). Si una dependencia es una función estándar `def` en lugar de `async def`, se ejecuta en el threadpool externo.

### Sub-dependencias { #sub-dependencies }

## Context Managers { #context-managers }

### "Context Managers" Nedir? { #what-are-context-managers }

"Context Managers", `with` ifadesiyle kullanabildiğiniz Python nesneleridir.

If not specified and the dependency has `yield`, it will have a `scope` of `"request"` by default.

### `scope` for sub-dependencies { #scope-for-sub-dependencies }

When you declare a dependency with a `scope="request"` (the default), any sub-dependency needs to also have a `scope` of `"request"`.

But a dependency with `scope` of `"function"` can have dependencies with `scope` of `"function"` and `scope` of `"request"`.

{* ../../docs_src/dependencies/tutorial008_an_py310.py hl[6,14,22] *}

І всі вони можуть використовувати `yield`.

У цьому випадку `dependency_c`, щоб виконати свій завершальний код, потребує, щоб значення з `dependency_b` (тут `dep_b`) все ще було доступним.

І, у свою чергу, `dependency_b` потребує, щоб значення з `dependency_a` (тут `dep_a`) було доступним для свого завершального коду.

例如，`dependency_c` 可以依赖 `dependency_b`，而 `dependency_b` 则依赖 `dependency_a`：

{* ../../docs_src/dependencies/tutorial008_an_py310.py hl[6,14,22] *}

并且它们都可以使用 `yield`。

在这种情况下，`dependency_c` 在执行其退出代码时需要 `dependency_b`（此处命名为 `dep_b`）的值仍然可用。

而 `dependency_b` 又需要 `dependency_a`（此处命名为 `dep_a`）的值在其退出代码中可用。

{* ../../docs_src/dependencies/tutorial008_an_py310.py hl[18:19,26:27] *}

{* ../../docs_src/dependencies/tutorial008_an_py310.py hl[6,14,22] *}

Et elles peuvent toutes utiliser `yield`.

Dans ce cas, `dependency_c`, pour exécuter son code de sortie, a besoin que la valeur de `dependency_b` (appelée ici `dep_b`) soit toujours disponible.

    Note over dep_req: ✅ Dependency closed
```

## `yield`, `HTTPException`, `except` 및 백그라운드 작업을 사용하는 의존성 { #dependencies-with-yield-httpexception-except-and-background-tasks }

`yield`를 사용하는 의존성은 시간이 지나면서 서로 다른 사용 사례를 다루고 일부 문제를 수정하기 위해 발전해 왔습니다.

# Dependency Injection

Use dependencies when:

* They can't be declared in Pydantic validation and require additional logic
* The logic depends on external resources or could block in any other way
* Other dependencies need their results (it's a sub-dependency)
* The logic can be shared by multiple endpoints to do things like error early, authentication, etc.
* They need to handle cleanup (e.g., DB sessions, file handles), using dependencies with `yield`