ReactiveExpr.show_widgets=False raises NotImplementedError in served app

[MarcSkovMadsen]

panel==1.3.8

I would expect to be able to use show_widgets=False in a server app. But it seems not

import panel as pn

pn.extension()

def calculate_power_generation(wind_speed, efficiency):
    power_generation = wind_speed * efficiency
    return f"Wind Speed: {wind_speed} m/s, Efficiency: {efficiency}, Power Generation: {power_generation:.1f} kW"

wind_speed = pn.widgets.FloatSlider(
    value=5, start=0, end=20, step=1, name="Wind Speed (m/s)"
)

efficiency = 0.3

calculate_power_fn = pn.rx(calculate_power_generation)(wind_speed=wind_speed, efficiency=efficiency)

pn.Column(
    wind_speed, pn.ReactiveExpr(calculate_power_fn, show_widgets=False)
).servable()

NotImplementedError:

Traceback (most recent call last):
  File "C:\repos\private\panel-docs\.venv\Lib\site-packages\bokeh\application\handlers\code_runner.py", line 229, in run
    exec(self._code, module.__dict__)
  File "C:\repos\private\panel-docs\app.py", line 19, in <module>
    ).servable()
      ^^^^^^^^^^
  File "C:\repos\private\panel-docs\.venv\Lib\site-packages\panel\viewable.py", line 396, in servable
    self.server_doc(title=title, location=location) # type: ignore
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\repos\private\panel-docs\.venv\Lib\site-packages\panel\viewable.py", line 1031, in server_doc
    model = self.get_root(doc)
            ^^^^^^^^^^^^^^^^^^
  File "C:\repos\private\panel-docs\.venv\Lib\site-packages\panel\layout\base.py", line 311, in get_root
    root = super().get_root(doc, comm, preprocess)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\repos\private\panel-docs\.venv\Lib\site-packages\panel\viewable.py", line 673, in get_root
    root = self._get_model(doc, comm=comm)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\repos\private\panel-docs\.venv\Lib\site-packages\panel\layout\base.py", line 177, in _get_model
    objects, _ = self._get_objects(model, [], doc, root, comm)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\repos\private\panel-docs\.venv\Lib\site-packages\panel\layout\base.py", line 159, in _get_objects
    child = pane._get_model(doc, root, model, comm)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\repos\private\panel-docs\.venv\Lib\site-packages\panel\viewable.py", line 568, in _get_model
    raise NotImplementedError
NotImplementedError

[philippjfr]

Fixed in https://github.com/holoviz/panel/pull/6396/files

[philippjfr]

That was the wrong link above but this issue has already been fixed in: #6392