# Security Tools

When you need to declare dependencies with OAuth2 scopes you use `Security()`.

But you still need to define what is the dependable, the callable that you pass as a parameter to `Depends()` or `Security()`.

There are multiple tools that you can use to create those dependables, and they get integrated into OpenAPI so they are shown in the automatic docs UI, they can be used by automatically generated clients and SDKs, etc.

    return response


@app.get("/user", dependencies=[Depends(set_up_request_state_dependency)])
def get_user():
    request_state = legacy_request_state_context_var.get()
    assert request_state
    return request_state["user"]


client = TestClient(app)


def test_dependency_contextvars():
    """
    Check that custom middlewares don't affect the contextvar context for dependencies.

    * <a href="https://fastapi.tiangolo.com/tutorial/dependencies/dependencies-in-path-operation-decorators/" class="external-link" target="_blank">Tutorial - Dependencies - Dependencies in path operation decorators</a>.
    * <a href="https://fastapi.tiangolo.com/tutorial/dependencies/global-dependencies/" class="external-link" target="_blank">Tutorial - Dependencies - Global Dependencies</a>.

previous build will be preserved and reused for the subsequent builds.

### Specifying Python dependencies

During bazel build all TensorFlow's Python dependencies are pinned to their
specific versions. This is necessary to ensure reproducibility of the build.
The pinned versions of the full transitive closure of TensorFlow's dependencies
together with their corresponding hashes are specified in

from fastapi import Depends, FastAPI

from .dependencies import get_query_token, get_token_header
from .internal import admin
from .routers import items, users

app = FastAPI(dependencies=[Depends(get_query_token)])


app.include_router(users.router)
app.include_router(items.router)
app.include_router(
    admin.router,
    prefix="/admin",
    tags=["admin"],
    dependencies=[Depends(get_token_header)],

            ),
        ] = None,
        dependencies: Annotated[
            Optional[Sequence[Depends]],
            Doc(
                """
                A list of global dependencies, they will be applied to each
                *path operation*, including in sub-routers.

                Read more about it in the

* Even dependencies can have dependencies, creating a hierarchy or **"graph" of dependencies**.
* All **automatically handled** by the framework.
* All the dependencies can require data from requests and **augment the path operation** constraints and automatic documentation.
* **Automatic validation** even for *path operation* parameters defined in dependencies.

def test_internal_error(client: TestClient):
    from docs_src.dependencies.tutorial008d import InternalError

    with pytest.raises(InternalError) as exc_info:
        client.get("/items/portal-gun")
    assert (
        exc_info.value.args[0] == "The portal gun is too dangerous to be owned by Rick"
    )


def test_internal_server_error():
    from docs_src.dependencies.tutorial008d import app

* Les arguments nommés à passer à la fonction de tâche (`message="some notification"`).

## Injection de dépendances

Utiliser `BackgroundTasks` fonctionne aussi avec le système d'injection de dépendances. Vous pouvez déclarer un paramètre de type `BackgroundTasks` à différents niveaux : dans une *fonction de chemin*, dans une dépendance, dans une sous-dépendance...

from fastapi import APIRouter, Depends, HTTPException

from ..dependencies import get_token_header

router = APIRouter(
    prefix="/items",
    tags=["items"],
    dependencies=[Depends(get_token_header)],
    responses={404: {"description": "Not found"}},
)


fake_items_db = {"plumbus": {"name": "Plumbus"}, "gun": {"name": "Portal Gun"}}


@router.get("/")
async def read_items():
    return fake_items_db