Tabulator does not automatically update the screen content when using streaming and remote pagination

[malemburg]

ALL software version info

Panel 1.6.1

Description of expected behavior and the observed behavior

When updating the table content using the .stream() method, Tabulator will normally automatically update the screen content with the new data.

This does happen when using the "local" pagination option, but it fails to do so with the "remote" pagination option. The screen only updates when e.g. clicking a header filter or sorting a column.

As a work-around, it's possible to reset the complete dataframe after calling .stream(), e.g. table.value = table.value, but that's not really the point, since .stream() is meant as an optimization.

Another trick is to temporarily update the table.pagesize, e.g. table.pagesize -=1; table.pagesize += 1, but this has some other undesired (visual) side-effects.

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

import panel as pn
import pandas as pd

def tabulator_test_case(case=1, pagination='remote', add_method=1, work_around=0):

    # Create a sample dataframe
    data = pd.DataFrame({
        'Name': ['Alice', 'Bob', 'Charlie'],
        'Age': [25, 30, 35],
        'City': ['New York', 'London', 'Paris']
    })

    # Create a Tabulator widget
    tabulator = pn.widgets.Tabulator(
        data,
        pagination=pagination,
        page_size=10,
        )

    # Action button
    add_row_button = pn.widgets.Button(
        name='Add Row',
    )
    def add_row(event):
        if add_method == 1:
            # Add row via .stream()
            tabulator.stream({
                'Name': [''],
                'Age': [0],
                'City': [''],
            })
        else:
            # Add row directly to data
            data.loc[len(data)] = ['', '', '']
        if work_around == 1:
            tabulator.value = tabulator.value
    add_row_button.on_click(add_row)

    # Create the layout
    layout = pn.Column(
        f"# Tabulator Demo {case}: {pagination=}, {add_method=}, {work_around=}",
        tabulator,
        add_row_button,
    )

    # Serve the app
    layout.servable()

 # works fine:
tabulator_test_case(1, pagination='local')

 # does not work - table doesn't update at all:
tabulator_test_case(2, pagination='local', add_method=2)

# table updates only after sorting:
tabulator_test_case(3, pagination='remote')

# works fine:
tabulator_test_case(4, pagination='remote', work_around=1)

# table updates only after sorting:
tabulator_test_case(5, pagination='remote', add_method=2)

# works fine:
tabulator_test_case(6, pagination='remote', add_method=2, work_around=1)

Stack traceback and/or browser JavaScript console output

Screenshots or screencasts of the bug in action

• I may be interested in making a pull request to address this

[Coderambling]

Hi @malemburg . Is the issue described below on the Panel Discourse regarding streaming and Tabulator possibly related? What does the local vs. remote pagination do?

https://discourse.holoviz.org/t/streaming-tabulator-column-filter/8426

Did the issue also occur in earlier versions of Panel? Is there an earlier version of Panel where things were working without issues?

Related info on streaming:

Discord thread on streaming in Panel with links / resources:: https://discord.com/channels/1075331058024861767/1335003374613037200

Async streaming:

https://discord.com/channels/1075331058024861767/1335003374613037200/1335023898516783114

https://discord.com/channels/1075331058024861767/1335003374613037200/1335023898516783114

[malemburg]

Hi @Coderambling , we have just started using Tabulator in Panel 1.6.1, so can't comment on earlier versions.

The missing visual update of the widget does not seem to have anything to do with filters set on the table. We tried removing those, but the effect remained the same: the table would only visually update when clicking e.g. on a column title to sort it.

I'll try to come up with a small example to show case the behavior and post it here.

The code special cases "remote" pagination in https://github.com/holoviz/panel/blob/main/panel/widgets/tables.py#L1648 and then returns without calling e.g. the various ._update_*() methods. I don't understand what the code there is doing, but the return looks a bit odd.

[Coderambling]

Thanks for the example! Hm. Not sure, but feels like a bug. I would suggest 2 things:

-Test / describe if the error persists if you set pagination to pagination=local . Does the bug persist?

-Cross-post your question and example code to the Holoviz Discourse https://discourse.holoviz.org

Hi.

Please ignore the last part of the previous version of this comment; I was confusing your issue with another one :-)

[malemburg]

I have created a set of test cases which demonstrate the various modes, issues and work-arounds:

import panel as pn
import pandas as pd

def tabulator_test_case(case=1, pagination='remote', add_method=1, work_around=0):

    # Create a sample dataframe
    data = pd.DataFrame({
        'Name': ['Alice', 'Bob', 'Charlie'],
        'Age': [25, 30, 35],
        'City': ['New York', 'London', 'Paris']
    })

    # Create a Tabulator widget
    tabulator = pn.widgets.Tabulator(
        data,
        pagination=pagination,
        page_size=10,
        )

    # Action button
    add_row_button = pn.widgets.Button(
        name='Add Row',
    )
    def add_row(event):
        if add_method == 1:
            # Add row via .stream()
            tabulator.stream({
                'Name': [''],
                'Age': [0],
                'City': [''],
            })
        else:
            # Add row directly to data
            data.loc[len(data)] = ['', '', '']
        if work_around == 1:
            tabulator.value = tabulator.value
    add_row_button.on_click(add_row)

    # Create the layout
    layout = pn.Column(
        f"# Tabulator Demo {case}: {pagination=}, {add_method=}, {work_around=}",
        tabulator,
        add_row_button,
    )

    # Serve the app
    layout.servable()

 # works fine:
tabulator_test_case(1, pagination='local')

 # does not work - table doesn't update at all:
tabulator_test_case(2, pagination='local', add_method=2)

# table updates only after sorting:
tabulator_test_case(3, pagination='remote')

# works fine:
tabulator_test_case(4, pagination='remote', work_around=1)

# table updates only after sorting:
tabulator_test_case(5, pagination='remote', add_method=2)

# works fine:
tabulator_test_case(6, pagination='remote', add_method=2, work_around=1)

Hope this helps in identifying the cause.

I would have expected all test cases to work fine (including the ones which directly change the dataframe).

(Also copied this into the OP)

[Coderambling]

Please ignore the last part of the previous comment; I was confusing your issue with another one :-)

WIll have a look today.

[Coderambling]

Can confirm I get the same results (when testing in Colab) @malemburg .

Additionally, in that environment, every time I click the button of layout 1 (which does create a new row), I get:

WARNING:param.Row01113: Comm received message that could not be deserialized.
WARNING:param.Row01113:Comm received message that could not be deserialized.