[Feature Request] Better Callback Context #1818

As suggested by @chriddyp in this forum post: creating a new triggered_dict would remove some boilerplate and make it possible to have more readable and intuitive code when using the callback_context

provide a more ergonomic:

triggered_id = callback_context.triggered[0]['prop_id']

For example, we could make a new triggered_dict that would have the same content but be a dictionary instead of a list. The logic would become:

def update_graph(b1, b2):
    if 'reset.n_clicks' in dash.callback_context.triggered_map:
        return reset_graph()
    elif 'draw.n_clicks'  in dash.callback_context.triggered_map:
        return draw_graph()

It would also be great to address PMC as well. See this this forum post:

Is there any good practice for parsing callback_context ? I recently started working more with pattern-matching callbacks and extracting certain values from the callback_context became essential. Until today, I have been doing things such as

idx = callback_context.states['packaging_concepts-div-waste_items.children'][-2]['props']['id']['index']

😬 😬

There must be a better way! Right?!