Function callback

dash/_callback.py:72–254

Normally used as a decorator, `@dash.callback` provides a server-side callback relating the values of one or more `Output` items to one or more `Input` items which will trigger the callback when they change, and optionally `State` items which provide additional information but d

(
    *_args,
    background: bool = False,
    interval: int = 1000,
    progress: Optional[Union[List[Output], Output]] = None,
    progress_default: Any = None,
    running: Optional[List[Tuple[Output, Any, Any]]] = None,
    cancel: Optional[Union[List[Input], Input]] = None,
    manager: Optional[BaseBackgroundCallbackManager] = None,
    cache_args_to_ignore: Optional[list] = None,
    cache_ignore_triggered=True,
    on_error: Optional[Callable[[Exception], Any]] = None,
    api_endpoint: Optional[str] = None,
    optional: Optional[bool] = False,
    hidden: Optional[bool] = None,
    websocket: Optional[bool] = False,
    persistent: Optional[bool] = False,
    mcp_enabled: Optional[bool] = None,
    mcp_expose_docstring: Optional[bool] = None,
    **_kwargs,
)

# pylint: disable=too-many-locals,too-many-arguments
def callback(
    *_args,
    background: bool = False,
    interval: int = 1000,
    progress: Optional[Union[List[Output], Output]] = None,
    progress_default: Any = None,
    running: Optional[List[Tuple[Output, Any, Any]]] = None,
    cancel: Optional[Union[List[Input], Input]] = None,
    manager: Optional[BaseBackgroundCallbackManager] = None,
    cache_args_to_ignore: Optional[list] = None,
    cache_ignore_triggered=True,
    on_error: Optional[Callable[[Exception], Any]] = None,
    api_endpoint: Optional[str] = None,
    optional: Optional[bool] = False,
    hidden: Optional[bool] = None,
    websocket: Optional[bool] = False,
    persistent: Optional[bool] = False,
    mcp_enabled: Optional[bool] = None,
    mcp_expose_docstring: Optional[bool] = None,
    **_kwargs,
) -> Callable[[Callable[Params, ReturnVar]], Callable[Params, ReturnVar]]:
    """
    Normally used as a decorator, `@dash.callback` provides a server-side
    callback relating the values of one or more `Output` items to one or
    more `Input` items which will trigger the callback when they change,
    and optionally `State` items which provide additional information but
    do not trigger the callback directly.

    `@dash.callback` is an alternative to `@app.callback` (where `app = dash.Dash()`)
    introduced in Dash 2.0.
    It allows you to register callbacks without defining or importing the `app`
    object. The call signature is identical and it can be used instead of `app.callback`
    in all cases.

    The last, optional argument `prevent_initial_call` causes the callback
    not to fire when its outputs are first added to the page. Defaults to
    `False` and unlike `app.callback` is not configurable at the app level.

    :Keyword Arguments:
        :param background:
            Mark the callback as a background callback to execute in a manager for
            callbacks that take a long time without locking up the Dash app
            or timing out.
        :param manager:
            A background callback manager instance. Currently, an instance of one of
            `DiskcacheManager` or `CeleryManager`.
            Defaults to the `background_callback_manager` instance provided to the
            `dash.Dash constructor`.
            - A diskcache manager (`DiskcacheManager`) that runs callback
              logic in a separate process and stores the results to disk using the
              diskcache library. This is the easiest backend to use for local
              development.
            - A Celery manager (`CeleryManager`) that runs callback logic
              in a celery worker and returns results to the Dash app through a Celery
              broker like RabbitMQ or Redis.
        :param running:
            A list of 3-element tuples. The first element of each tuple should be
            an `Output` dependency object referencing a property of a component in