[Python] How to get an "Edit" button to be visible only when the user has clicked on a row in...

I'd like to make it so that when the user loads that app and looks at the "Session" tab of the app, that there is a "New" button visible that will eventually take them to a new record form. If the user selects a row in the existing table though, I want an "Edit" button to be visible so they can edit that single selected row.

For the most part I have this functionality working, however I'm having some trouble with the Edit button flickering on and off when a row is selected before finally goes invisible. I believe the problem has to do with my selected_active_practive_session() reactive calculation. When I step through the execution, it returns the correct row id the first time, but then the Shiny App forces it to run again, and again, ultimately changing the output value to None. This causes the "Edit" button to flicker on and off before staying off.

#core
import pandas as pd

# Web/Visual frameworks
from shiny import App, ui, render, reactive, types

df_sessions = pd.DataFrame(
{'Date':['9-1-2024','9-2-2024','9-3-2024','9-4-2024'],
'Song_id':[1,1,2,2],
'Notes':['Focused on tempo (65bpm)','focused on tempo (70bpm)','Started learning first page','Worked on first page']})

app_ui = ui.page_fluid(
ui.page_navbar(
ui.nav_panel("New Practice Session", "New Practice Session - Input Form"),
ui.nav_panel("New Song", "New Song - Input Form"),
ui.nav_panel("New Artist", "New Artist - Input Form"),
title="Guitar Study Tracker",
id="page",
),
ui.output_ui('page_manager'),
)



def server(input, output, session):

def nav_song(): # Placeholder
return "Song"

def nav_artist(): # Placeholder
return "Artist"

@render.data_frame
def session_summary():
return render.DataGrid(
df_sessions,
width="100%",
height="100%",
selection_mode="row"
)


@reactive.calc()
def selected_active_practice_session():
"""Returns the row id of a selected row, otherwise returns None"""
try:
row_id = session_summary.cell_selection()['rows']
row_id = row_id[0] if len(row_id)>0 else None # sets row_id to the selected row or None otherwise
except types.SilentException as e: # On first run this control will not exist by default - catch it's SilentException
row_id=None
return row_id

@reactive.calc
def ui_practice_session_button():
if selected_active_practice_session() is not None:
return ui.input_action_button("btn_update_session", "Update", width='100%')
else:
return None

@reactive.calc
def nav_practice_session():
ret_ui = ui.row(
ui.row(ui.column(2, ui_practice_session_button()),
ui.column(8),
ui.column(2,ui.input_action_button("btn_new_session", "New", width="100%")),
),

ui.output_data_frame("session_summary")
)
return ret_ui

@render.ui
def page_manager():
if input.page()=="New Practice Session":
return nav_practice_session()
if input.page()=="New Song":
return nav_song()
if input.page()=="New Artist":
return nav_artist()
return None

app = App(app_ui, server)

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