**FastAPI** includes utilities for all these OAuth2 authentication flows in `fastapi.security.oauth2`.

## `Security` in decorator `dependencies`

would be valid to use as a **FastAPI** dependency.

In fact, FastAPI uses those two decorators internally.

///

## A database dependency with `yield`

For example, you could use this to create a database session and close it after finishing.

    * Zuerst werden die Router-Abhängigkeiten ausgeführt, dann die [`dependencies` im Dekorator](dependencies/dependencies-in-path-operation-decorators.md){.internal-link target=_blank} und dann die normalen Parameterabhängigkeiten.

/// tip | "Dica"

Observe que, assim como [dependências em *decoradores de operação de rota*](dependencies/dependencies-in-path-operation-decorators.md){.internal-link target=_blank}, nenhum valor será passado para sua *função de operação de rota*.

///

O resultado final é que os caminhos dos itens agora são:

But for those additional responses you have to make sure you return a `Response` like `JSONResponse` directly, with your status code and content.

## Additional Response with `model`

You can pass to your *path operation decorators* a parameter `responses`.

It receives a `dict`: the keys are status codes for each response (like `200`), and the values are other `dict`s with the information for each of them.

      - tutorial/dependencies/index.md
      - tutorial/dependencies/classes-as-dependencies.md
      - tutorial/dependencies/sub-dependencies.md
      - tutorial/dependencies/dependencies-in-path-operation-decorators.md
      - tutorial/dependencies/global-dependencies.md
      - tutorial/dependencies/dependencies-with-yield.md
    - Security:
      - tutorial/security/index.md
      - tutorial/security/first-steps.md

You put it on top of a function. Like a pretty decorative hat (I guess that's where the term came from).

A "decorator" takes the function below and does something with it.

In our case, this decorator tells **FastAPI** that the function below corresponds to the **path** `/` with an **operation** `get`.

It is the "**path operation decorator**".

///

You can also use the other operations:

* `@app.post()`
* `@app.put()`

我们还可以添加一个 `tags` 列表和额外的 `responses` 列表，这些参数将应用于此路由器中包含的所有*路径操作*。

我们可以添加一个 `dependencies` 列表，这些依赖项将被添加到路由器中的所有*路径操作*中，并将针对向它们发起的每个请求执行/解决。

/// tip

请注意，和[*路径操作装饰器*中的依赖项](dependencies/dependencies-in-path-operation-decorators.md){.internal-link target=_blank}很类似，没有值会被传递给你的*路径操作函数*。

///

最终结果是项目相关的路径现在为：

* `/items/`
* `/items/{item_id}`

...如我们所愿。

* 它们将被标记为仅包含单个字符串 `"items"` 的标签列表。

## `Security` 👨‍🎨 `dependencies`

**FastAPI** 的 `fastapi.security.oauth2` 里包含了所有 OAuth2 身份验证流工具。

## 装饰器 `dependencies` 中的 `Security`