Passing variables from widget values to further functions on button click

Widgets
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1

I have two questions/problems:

I am trying to generate an interface where the user can select options from combobox/dropdowns, add some detail text then click a button which executes a function using the values initially input by the user. This should be re-runnable ie. if they change the values they can hit the button again to rerun the function using the new values.

Question 1
Currently the function does not run on clicking the button (non-working version below - nothing printed out). In case it is relevant since I believe Jupyter doesn’t handle print from widgets well, the final function won’t be printing output it will be executing other functions to go retrieve data and manipulate it before returning something (likely needing to be displayed).

Question 2
I’d also like the optW text box (or possibly different widget) to appear as needed based on the option selected in the third dropdown but as soon as I add another .observe the first one (which changes the options for the combobox stops working).

Code below, any help appreciated.

Using:
Python 3.9.19 (unable to update due to matching client system)
ipywidgets 8.1.3
JupyterLab 4.0.11

import ipywidgets as widgets
from IPython.display import display

hdrm = {'APPLE BLUE': ['12345852'], 'APPLE BROWN': ['12345684', '12345738', '12345756'], 'APPLE GREEN': ['12345697', '12345841', '12345873'], 'APPLE ORANGE': ['12345826'], 'APPLE PINK': ['12345690', '12345698', '12345872'], 'APPLE PURPLE': ['12345727', '12345784', '12345859', '12345862'], 'APPLE RED': ['12345692', '12345711', '12345777', '12345806'], 'APPLE YELLOW': ['12345767', '12345809', '12345824', '12345855']}

# This function updates the options for the LID combobox based on the user choice from the nickname combobox
def update_lid_options(*args, **kwargs): 
    try:
        lidW.value = ''
        lidW.options = hdrm_dict[nicknameW.value]
        print(hdrm_dict[nicknameW.value])
    except:
        lidW.options = ['']
        print('Failed to update')

# This function represents further code which should be executed when the button is pressed
def print_lid(idx,task,details):
    with output:
        print(idx,task,details)

# First combobox (nickname)
nicknameW = widgets.Combobox(
    placeholder='APPLE GREEN',
    options=list(hdrm_dict.keys()),
    description='Name:',
    ensure_option=True,
    disabled=False
)

# Second combobox (id)
lidW = widgets.Combobox(
    placeholder='12345678',
    options = [''],
    description='ID:',
    ensure_option=True,
    disabled=False
)

# Dropdown (option)
optW = widgets.Dropdown(
    placeholder='Choose option',
    options=['Task1','Task2','Task3'],
    description='Task',
    ensure_option=True,
    disabled=False
)

# Text box (details)
detailsW = widgets.Textarea(
    value='',
    placeholder='Further details',
    description='String:',
    disabled=False
)

# Button to run function
buttonW = widgets.Button(description='Print LID')
# Output widget
outputW = widgets.Output()

# Display widgets
display(nicknameW,lidW,optW,detailsW,buttonW,outputW)

# Monitors the first combobox and updates the second combobox based on the selection
nicknameW.observe(update_lid_options)

# On click button should execute further code using variables from the value of the widgets
buttonW.on_click(print_lid(lidW.value,optW.value,detailsW.value))

What the widgets currently look like:

Screenshot 2024-06-19 at 12.01.00
Screenshot 2024-06-19 at 12.01.00758×374 8.29 KB

2

The example is a bit complex: would recommend getting the smallest thing (not) running first.

At first glance: on_click takes a function, not the output of a function, so more like .on_click(print_lid).

If it is unpalatable to reference the variables inside print_lid, make a second one, e.g. def on_click) that gathers all the values and documents its intent more clearly.

As for whether something shows based on another widget’s value: dlink is great: the third option provides a callable which has a much simpler signature than observe.

1 Like
5

This solved the issue - turned out to be an issue with the handling of the output/print. The observe function triggering a handler that modified the widget.layout.display attribute worked for making widgets visibly based on the user selections.

Thanks for the help :slight_smile: