return form_data


@app.get("/users/me")
def read_users_me(current_user: Optional[User] = Depends(get_current_user)):
    if current_user is None:
        return {"msg": "Create an account first"}
    return current_user


client = TestClient(app)


def test_security_oauth2():
    response = client.get("/users/me", headers={"Authorization": "Bearer footokenbar"})

You can connect with <a href="https://tiangolo.com" class="external-link" target="_blank">me (Sebastián Ramírez / `tiangolo`)</a>, the author.

You can:

* <a href="https://github.com/tiangolo" class="external-link" target="_blank">Follow me on **GitHub**</a>.
    * See other Open Source projects I have created that could help you.
    * Follow me to see when I create a new Open Source project.

它们会为每个*路径操作*进行单独检查。

## 查看文档

打开 API 文档，进行身份验证，并指定要授权的作用域。

<img src="/img/tutorial/security/image11.png">

没有选择任何作用域，也可以进行**身份验证**，但访问 `/uses/me` 或 `/users/me/items` 时，会显示没有足够的权限。但仍可以访问 `/status/`。

如果选择了作用域 `me`，但没有选择作用域 `items`，则可以访问 `/users/me/`，但不能访问 `/users/me/items`。

这就是通过用户提供的令牌使用第三方应用访问这些*路径操作*时会发生的情况，具体怎样取决于用户授予第三方应用的权限。

## 关于第三方集成

本例使用 OAuth2 **密码**流。

这种方式适用于登录我们自己的应用，最好使用我们自己的前端。

    return form_data


@app.get("/users/me")
# Here we use string annotations to test them
def read_current_user(current_user: "User" = Depends(get_current_user)):
    return current_user


client = TestClient(app)


def test_security_oauth2():
    response = client.get("/users/me", headers={"Authorization": "Bearer footokenbar"})
    assert response.status_code == 200, response.text

Und wenn Sie den Scope `me`, aber nicht den Scope `items` auswählen, können Sie auf `/users/me/` zugreifen, aber nicht auf `/users/me/items/`.

                },
            ]
        }
    )


def test_users_me_token_jessica(client: TestClient):
    response = client.get("/users/me?token=jessica")
    assert response.status_code == 200
    assert response.json() == {"username": "fakecurrentuser"}


def test_users_me_with_no_token(client: TestClient):
    response = client.get("/users/me")
    assert response.status_code == 422
    assert response.json() == IsDict(

                },
            ]
        }
    )


def test_users_me_token_jessica(client: TestClient):
    response = client.get("/users/me?token=jessica")
    assert response.status_code == 200
    assert response.json() == {"username": "fakecurrentuser"}


def test_users_me_with_no_token(client: TestClient):
    response = client.get("/users/me")
    assert response.status_code == 422
    assert response.json() == IsDict(

            ]
        }
    )


@needs_py39
def test_users_me_token_jessica(client: TestClient):
    response = client.get("/users/me?token=jessica")
    assert response.status_code == 200
    assert response.json() == {"username": "fakecurrentuser"}


@needs_py39
def test_users_me_with_no_token(client: TestClient):
    response = client.get("/users/me")
    assert response.status_code == 422

Algo como `/users/me` por exemplo, digamos que essa rota seja utilizada para pegar dados sobre o usuário atual.

E então você pode ter também uma rota `/users/{user_id}` para pegar dados sobre um usuário específico associado a um ID de usuário.

Porque as operações de rota são avaliadas em ordem, você precisa ter certeza que a rota para `/users/me` está sendo declarado antes da rota `/users/{user_id}`:

下一章介绍详细内容。

## 顺序很重要

有时，*路径操作*中的路径是写死的。

比如要使用 `/users/me` 获取当前用户的数据。

然后还要使用 `/users/{user_id}`，通过用户 ID 获取指定用户的数据。

由于*路径操作*是按顺序依次运行的，因此，一定要在 `/users/{user_id}` 之前声明 `/users/me` ：

```Python hl_lines="6  11"
{!../../../docs_src/path_params/tutorial003.py!}
```

否则，`/users/{user_id}` 将匹配 `/users/me`，FastAPI 会**认为**正在接收值为 `"me"` 的 `user_id` 参数。

## 预设值