app = FastAPI()


@app.api_route("/api_route")
def non_operation():
    return {"message": "Hello World"}


def non_decorated_route():
    return {"message": "Hello World"}


app.add_api_route("/non_decorated_route", non_decorated_route)


@app.get("/text")
def get_text():
    return "Hello World"


@app.get("/path/{item_id}")
def get_id(item_id):
    return item_id

                methods=methods,
                name=name,
                include_in_schema=include_in_schema,
            )
            return func

        return decorator

    def add_api_route(
        self,
        path: str,
        endpoint: Callable[..., Any],
        *,
        response_model: Any = Default(None),
        status_code: Optional[int] = None,

        if self.root_path:
            scope["root_path"] = self.root_path
        await super().__call__(scope, receive, send)

    def add_api_route(
        self,
        path: str,
        endpoint: Callable[..., Any],
        *,
        response_model: Any = Default(None),
        status_code: Optional[int] = None,

### Refactors

* 🎨 Fix typing annotation for semi-internal `FastAPI.add_api_route()`. PR [#10240](https://github.com/fastapi/fastapi/pull/10240) by [@ordinary-jamie](https://github.com/ordinary-jamie).