Linking not working

[WillFrasier]

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ALL software version info

(this library, plus any other relevant software, e.g. bokeh, python, notebook, OS, browser, etc)

Package Version
bokeh 2.4.3
datashader 0.14.1
holoviews 1.14.9
hvplot 0.8.0
ipykernel 5.1.4
ipython 7.19.0
ipython-genutils 0.2.0
ipywidgets 8.0.2
jupyter 1.0.0
jupyter-bokeh 3.0.5
jupyter-client 6.1.12
jupyter-console 6.4.0
jupyter-core 4.7.1
jupyter-packaging 0.7.12
jupyter-server 1.4.1
jupyterlab 3.0.14
jupyterlab-pygments 0.1.2
jupyterlab-server 2.4.0
jupyterlab-widgets 3.0.3
pandas 1.2.4
panel 0.13.1
param 1.12.2
pip 22.3
plotly 5.7.0

VS Code Version Info:
Version: 1.72.2 (user setup)
Commit: d045a5eda657f4d7b676dedbfa7aab8207f8a075
Date: 2022-10-12T22:15:18.074Z
Electron: 19.0.17
Chromium: 102.0.5005.167
Node.js: 16.14.2
V8: 10.2.154.15-electron.0
OS: Windows_NT x64 10.0.22621
Sandboxed: No

Description of expected behavior and the observed behavior

Linking is not working.

• Create a dashboard or linked widget (code samples below)
• Change a parameter

Expected:
The linked code is called, print statements are visible and value in the UI is changed

Actual
Nothing appears to happen at all. Print statements do not show and output in the UI does not change

I have followed the docs but these do not working on several different machines i have been on.

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

Creating an automatic dashboard not working

First render works fine, but then changing the drop down does nothing.

import panel as pn
import pandas as pd
from datetime import date, datetime, timedelta
import param
import holoviews as hv

hv.extension('plotly')

regions = ['United States of America', 'Greater China', 'Japan']

class DashboardTest(param.Parameterized):
    region = param.Selector(default='Japan', objects=regions)

    @param.depends('region')
    def on_update(self):

        print(f'on_update: {datetime.now()}')
        
        return pn.pane.Markdown(f"""
                # Chart Updated: {datetime.now()}
                
                region: {self.region}                         
        """)

explorer = DashboardTest()
row = pn.Row(
    pn.Column(explorer.param),
    explorer.on_update
)
row

Basic linking not working

This is copied directly from the (docs site on linking)[https://panel.holoviz.org/user_guide/Links.html]. Again, first render works fine but changing the text does not cause the output to change

markdown = pn.pane.Markdown("Some text")
text_input = pn.widgets.TextInput(value=markdown.object)

text_input.link(markdown, value='object')

pn.Row(text_input, markdown)

Stack traceback and/or browser JavaScript console output

None. I'm not seeing anything.

Screenshots or screencasts of the bug in action

[philippjfr]

Very odd, both cases are working fine for me. Can you tell me which notebook environment you are using here?

[WillFrasier]

Thanks for quick reply. I was using VSCode, Windows 11.

Figured it out.

I should have been calling:

pn.extension()

I wasted a ton of time trying to figure this one out. Any chance we could add a warning or message indicating that pn.extension() needs to be called?