Syncing a widget's value as query parameter does not trigger value_throttled-bound callbacks

[MP-MaximilianLattka]

ALL software version info

Software Version Info

Python 3.12.7
Panel 1.5.3

Description of expected behavior and the observed behavior

While using widgets that support a value_throttled attribute (e.g. RangeSlider) and binding value_throttled to a callback works out fine, syncing the widget's value as a query parameter does not trigger the callback. It's worth mentioning that the widget's value is updated with the query parameters value.

In other words, while syncing a widget's value with a query parameter, the query parameter does not fire callbacks that are bound to value_throttled.

(Please don't confuse this issue with #7481 which features a similar code snippet)

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

import panel as pn
import pandas as pd

pn.extension("tabulator", notifications=False)

template = pn.template.BootstrapTemplate()

df_full = pd.DataFrame({"year": list(range(2000, 2021))})

table = pn.widgets.Tabulator(df_full)
slider = pn.widgets.RangeSlider(start=2000, end=2020, name='Years')

@pn.depends(slider.param.value_throttled, watch=True)
def filter_df(value):
    start, end = value
    table.value = df_full[(df_full["year"] >= start) & (df_full["year"] <= end)]

if pn.state.location:
    pn.state.location.sync(slider, {"value": "years"})

template.main.append(pn.Column(table))
template.sidebar.append(pn.Column(slider))
template.servable();

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

[jbednar]

Once you have the code above, you can reproduce this issue by serving that app with e.g. panel serve --port 5099 throttled_sync.py and visiting "http://localhost:5099/throttled_sync?years=%5B2000%2C+2007%5D". I find that it only respects the URL parameter when depending on value, even though (as I understand it) it should be fine to depend on value_throttled as well.

[nellenul]

I've run into the same issue as well, thanks for posting 👀