8. Notice that this *path operation function* uses regular `def` instead of `async def`.

    As always, in FastAPI you can combine `def` and `async def` as needed.

    If you need a refresher about when to use which, check out the section _"In a hurry?"_ in the docs about [`async` and `await`](../async.md#in-a-hurry){.internal-link target=_blank}.

func ReadSysctl(key string) (string, error) {
	data, err := os.ReadFile(key)
	if err != nil {
		return "", err
	}
	return strings.TrimSpace(string(data)), nil
}

func forEachLoopbackRoute(cfg *Config, operation string, f func(*netlink.Route) error) error {
	loopbackLink, err := netlink.LinkByName("lo")
	if err != nil {
		return fmt.Errorf("failed to find 'lo' link: %v", err)
	}

	// Set up netlink routes for localhost

                            },
                        },
                        "200": {"description": "Successful Response"},
                    },
                    "summary": "A",
                    "operationId": "a_a_get",
                }
            },
            "/b": {
                "get": {
                    "responses": {
                        "500": {
                            "description": "Error",

    return {"name": fake_items_db[item_id]["name"], "item_id": item_id}


@router.put(
    "/{item_id}",
    tags=["custom"],
    responses={403: {"description": "Operation forbidden"}},
)
async def update_item(item_id: str):
    if item_id != "plumbus":
        raise HTTPException(
            status_code=403, detail="You can only update the item: plumbus"
        )

                            "content": {"application/vnd.api+json": {"schema": {}}},
                        },
                    },
                    "summary": "A",
                    "operationId": "a_a_get",
                }
            },
            "/b": {
                "get": {
                    "responses": {
                        "500": {
                            "description": "Error",

                            },
                        },
                        "204": {"description": "Successful Response"},
                    },
                    "summary": "A",
                    "operationId": "a_a_get",
                }
            },
            "/b": {
                "get": {
                    "responses": {
                        "204": {"description": "No Content"},

                                }
                            },
                        },
                    },
                    "summary": "Login For Access Token",
                    "operationId": "login_for_access_token_token_post",
                    "requestBody": {
                        "content": {
                            "application/x-www-form-urlencoded": {
                                "schema": {

## Ersetzendes Aktualisieren mit `PUT`

Um einen Artikel zu aktualisieren, können Sie die <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/PUT" class="external-link" target="_blank">HTTP `PUT`</a> Operation verwenden.

        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/model-with-tuple/": {
                "post": {
                    "summary": "Post Model With Tuple",
                    "operationId": "post_model_with_tuple_model_with_tuple__post",
                    "requestBody": {
                        "content": {
                            "application/json": {

# Request Parameters

Here's the reference information for the request parameters.

These are the special functions that you can put in *path operation function* parameters or dependency functions with `Annotated` to get data from the request.

It includes:

* `Query()`
* `Path()`
* `Body()`
* `Cookie()`
* `Header()`
* `Form()`
* `File()`

You can import them all directly from `fastapi`:

```python