Tabulator selection value not updating in Voila app

[dcnadler]

ALL software version info

Docker image: python:3.9

panel==0.14.0
bokeh==2.4.3
jupyter-bokeh==3.0.5
jupyter-core==4.11.1
jupyter-server==1.19.1
jupyter_client==7.3.5
jupyterlab_server==2.15.2

tested both:
voila==0.3.6
ipywidgets==7.7.2
and
voila==0.4.0a2
ipywidgets==8.0.2

Description of expected behavior and the observed behavior

When using a Tabulator widget in a voila app, the selection and selected_dataframe attribute values do not change from the initial values even when the front-end selection changes.

Complete, minimal, self-contained example code that reproduces the issue

.ipynb file that's served with voila:

import pandas as pd
from IPython.display import display, Markdown
import ipywidgets as ipw
from ipywidgets import VBox
import panel as pn
pn.extension('tabulator')
df = pd.DataFrame({'a': [1, 2, 3, 4], 'b': [5, 6, 7, 8], 'c': [9, 10, 11, 12]})

show_btn = ipw.Button(description = 'Show Selection')

table_widget = pn.widgets.Tabulator(df, selectable='checkbox')

output = ipw.Output()

@output.capture(clear_output = True)
def display_selection(b):
    print('Selected dataframe')
    print(table_widget.selected_dataframe)
    print('-------')
    print('Selection')
    print(table_widget.selection)
        
show_btn.on_click(display_selection)

display(Markdown("## Test tabulator"))

display(VBox([pn.ipywidget(table_widget), show_btn, output]))

The initial table has no selection and when rows are selected and the callback is triggered, the printed output still has no selection:

Selected dataframe
Empty DataFrame
Columns: [a, b, c]
Index: []
-------
Selection
[]

However, if this notebook is run in JupyterLab (not voila) the selection is reflected in the output:

Selected dataframe
   a  b   c
1  2  6  10
2  3  7  11
-------
Selection
[1, 2]

Thanks!

[hhlim333]

Anyone to solve this problem?

[Kalandoros]

I can confirm there is a bug as described by dcnadler.
I also became aware that the on_click callback seems generally not to work in voila whereas it does in Jupyterlab.
Maybe it is the right approach to look for on_click as the root cause.

Python: 3.11.5
panel==0.3.6
bokeh==3.2.2
jupyter-bokeh==3.0.7
jupyter-core==5.3.0
jupyter-server==2.7.3
jupyter_client==8.1.0
jupyterlab_server==2.25.0
voila==0.5.5
ipywidgets==8.1.1