SOLVED: Updating Select widget options on new value gives ValueError

Panel
3

I managed to temporarily resolve the issue by replacing the Select widget with a new one, here is updated working code

import panel as pn

pn.extension()

placeholder_code = '---SELECT OPTION---'

def create_select():
    return pn.widgets.Select(size=10)

def create_parent_select(label_widget, code):
    def get_parent_options(code):
        ...

    options = get_parent_options(code)

    parent_select = create_select()
    parent_select.link(label_widget, callbacks={'value': set_label_widget})

    if options == []:
        parent_select.disabled = True
        parent_select.options = []
    else:
        parent_select.options = [placeholder_code] + options

    return parent_select

def create_children_select(label_widget, code):
    def get_children_options(code):
        ...

    children_select = create_select()
    children_select.link(label_widget, callbacks={'value': set_label_widget})

    options = get_children_options(code)

    if options == []:
        children_select.disabled = True
        children_select.options = []
    else:
        children_select.options =  [placeholder_code] + options

    return children_select

def create_dashboard(dashboard, starting_code="root"):
    if starting_code == placeholder_code:
        return

    dashboard.clear()

    label_widget = pn.widgets.StaticText(value=starting_code)
    parent_select = create_parent_select(label_widget, starting_code)
    children_select = create_children_select(label_widget, starting_code)

    dashboard.append(parent_select)
    dashboard.append(label_widget)
    dashboard.append(children_select)

    return dashboard

dashboard = pn.Row()

Updating = True
create_dashboard(dashboard)
Updating = False

def set_label_widget(target, event):
    global Updating
    global dashboard

    if Updating:
        return

    Updating = True
    create_dashboard(dashboard, event.new)
    Updating = False

dashboard.servable()

Essentially with each new option selection, I remove the old widget and create a new one with the updated options. I needed to append a place holder option, that is skipped on purpose, because otherwise it would right away callback again on the new selection of first element in widget upon creation.

For my purposes, the option lists are small and therefore it is acceptable solution for the time being.

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