依赖项 - Depends() 和 Security()

Depends()

依赖项主要通过特殊的函数 Depends() 来处理，该函数接受一个可调用对象。

这是其及其参数的参考。

你可以直接从 fastapi 导入它

from fastapi import Depends

fastapi.Depends

Depends(dependency=None, *, use_cache=True)

声明一个 FastAPI 依赖项。

它接受一个 "可依赖的" 可调用对象（如函数）。

不要直接调用它，FastAPI 会为你调用它。

在 FastAPI 依赖项文档 中阅读更多相关内容。

示例

from typing import Annotated

from fastapi import Depends, FastAPI

app = FastAPI()


async def common_parameters(q: str | None = None, skip: int = 0, limit: int = 100):
    return {"q": q, "skip": skip, "limit": limit}


@app.get("/items/")
async def read_items(commons: Annotated[dict, Depends(common_parameters)]):
    return commons

参数	描述
dependency	一个“可依赖的”可调用对象（如函数）。 不要直接调用它，FastAPI 会为你调用它，只需直接传递对象即可。 类型: Optional[Callable[..., Any]] 默认值: None
use_cache	默认情况下，当一个依赖项在请求中首次被调用后，如果该依赖项在请求的其余部分中再次声明（例如，如果多个依赖项需要它），则该值将被重用于请求的其余部分。 将 use_cache 设置为 False 以禁用此行为，并确保在同一请求中再次调用该依赖项（如果声明了不止一次）。 类型: bool 默认值: True

源代码位于 fastapi/param_functions.py

def Depends(  # noqa: N802
    dependency: Annotated[
        Optional[Callable[..., Any]],
        Doc(
            """
            A "dependable" callable (like a function).

            Don't call it directly, FastAPI will call it for you, just pass the object
            directly.
            """
        ),
    ] = None,
    *,
    use_cache: Annotated[
        bool,
        Doc(
            """
            By default, after a dependency is called the first time in a request, if
            the dependency is declared again for the rest of the request (for example
            if the dependency is needed by several dependencies), the value will be
            re-used for the rest of the request.

            Set `use_cache` to `False` to disable this behavior and ensure the
            dependency is called again (if declared more than once) in the same request.
            """
        ),
    ] = True,
) -> Any:
    """
    Declare a FastAPI dependency.

    It takes a single "dependable" callable (like a function).

    Don't call it directly, FastAPI will call it for you.

    Read more about it in the
    [FastAPI docs for Dependencies](https://fastapi.org.cn/tutorial/dependencies/).

    **Example**

    ```python
    from typing import Annotated

    from fastapi import Depends, FastAPI

    app = FastAPI()


    async def common_parameters(q: str | None = None, skip: int = 0, limit: int = 100):
        return {"q": q, "skip": skip, "limit": limit}


    @app.get("/items/")
    async def read_items(commons: Annotated[dict, Depends(common_parameters)]):
        return commons
    ```
    """
    return params.Depends(dependency=dependency, use_cache=use_cache)

Security()

对于许多场景，你可以使用依赖项（即 Depends()）来处理安全（授权、认证等）。

但是当你还想声明 OAuth2 范围时，你可以使用 Security() 而不是 Depends()。

你可以直接从 fastapi 导入 Security()

from fastapi import Security

fastapi.Security

Security(dependency=None, *, scopes=None, use_cache=True)

声明一个 FastAPI 安全依赖项。

与普通依赖项的唯一区别是它可以声明 OAuth2 范围，这些范围将与 OpenAPI 和自动 UI 文档（默认在 /docs）集成。

它接受一个 "可依赖的" 可调用对象（如函数）。

不要直接调用它，FastAPI 会为你调用它。

在 FastAPI 安全文档 和 FastAPI OAuth2 范围文档 中阅读更多相关内容。

示例

from typing import Annotated

from fastapi import Security, FastAPI

from .db import User
from .security import get_current_active_user

app = FastAPI()

@app.get("/users/me/items/")
async def read_own_items(
    current_user: Annotated[User, Security(get_current_active_user, scopes=["items"])]
):
    return [{"item_id": "Foo", "owner": current_user.username}]

参数	描述
dependency	一个“可依赖的”可调用对象（如函数）。 不要直接调用它，FastAPI 会为你调用它，只需直接传递对象即可。 类型: Optional[Callable[..., Any]] 默认值: None
scopes	使用此 Security 依赖项的路径操作所需的 OAuth2 范围。 "范围"一词来自 OAuth2 规范，它似乎故意模糊且可解释。它通常指权限，在某些情况下指角色。 这些范围与 OpenAPI（以及 /docs 处的 API 文档）集成。因此它们在 OpenAPI 规范中是可见的。 类型: Optional[Sequence[str]] 默认值: None
use_cache	默认情况下，当一个依赖项在请求中首次被调用后，如果该依赖项在请求的其余部分中再次声明（例如，如果多个依赖项需要它），则该值将被重用于请求的其余部分。 将 use_cache 设置为 False 以禁用此行为，并确保在同一请求中再次调用该依赖项（如果声明了不止一次）。 类型: bool 默认值: True

源代码位于 fastapi/param_functions.py

def Security(  # noqa: N802
    dependency: Annotated[
        Optional[Callable[..., Any]],
        Doc(
            """
            A "dependable" callable (like a function).

            Don't call it directly, FastAPI will call it for you, just pass the object
            directly.
            """
        ),
    ] = None,
    *,
    scopes: Annotated[
        Optional[Sequence[str]],
        Doc(
            """
            OAuth2 scopes required for the *path operation* that uses this Security
            dependency.

            The term "scope" comes from the OAuth2 specification, it seems to be
            intentionally vague and interpretable. It normally refers to permissions,
            in cases to roles.

            These scopes are integrated with OpenAPI (and the API docs at `/docs`).
            So they are visible in the OpenAPI specification.
            )
            """
        ),
    ] = None,
    use_cache: Annotated[
        bool,
        Doc(
            """
            By default, after a dependency is called the first time in a request, if
            the dependency is declared again for the rest of the request (for example
            if the dependency is needed by several dependencies), the value will be
            re-used for the rest of the request.

            Set `use_cache` to `False` to disable this behavior and ensure the
            dependency is called again (if declared more than once) in the same request.
            """
        ),
    ] = True,
) -> Any:
    """
    Declare a FastAPI Security dependency.

    The only difference with a regular dependency is that it can declare OAuth2
    scopes that will be integrated with OpenAPI and the automatic UI docs (by default
    at `/docs`).

    It takes a single "dependable" callable (like a function).

    Don't call it directly, FastAPI will call it for you.

    Read more about it in the
    [FastAPI docs for Security](https://fastapi.org.cn/tutorial/security/) and
    in the
    [FastAPI docs for OAuth2 scopes](https://fastapi.org.cn/advanced/security/oauth2-scopes/).

    **Example**

    ```python
    from typing import Annotated

    from fastapi import Security, FastAPI

    from .db import User
    from .security import get_current_active_user

    app = FastAPI()

    @app.get("/users/me/items/")
    async def read_own_items(
        current_user: Annotated[User, Security(get_current_active_user, scopes=["items"])]
    ):
        return [{"item_id": "Foo", "owner": current_user.username}]
    ```
    """
    return params.Security(dependency=dependency, scopes=scopes, use_cache=use_cache)