python - I am having a NoneType error on exiting GUI

Question

In the following code I get a NoneType Error when exiting the GUI. The interface seems to work fine otherwise, but when exiting it tells me "-Tables-" is not subscriptable in line 77 which is 'if values['-Tables-'] == True:'

My guess is that I'm somehow executing the while loop again after I break the code, or something? (There's a bunch more if statements I took out in the middle, but no errors till adding these radiobutton functions.)

import os 
import shutil
import sys
import math
import openpyxl
from datetime import datetime
from docx import Document
from docx.shared import Inches
from docx.oxml.table import CT_Tbl
from docx.oxml.text.paragraph import CT_P
from docx.table import Table
import PySimpleGUI as sg
import traceback

# Define the window's contents

tab1_layout =  [
          [sg.Text('Copy/Paste the row of the SC, CA, or CC from Teams')],
          [sg.Text('Customer name should have - rather than spaces')],
          [sg.Input(key='-INPUT-')],
          [sg.Text(size=(40,5), key='-OUTPUT-')],
          [sg.Checkbox('Delete Revision History', default=True, key='-Rev-'), sg.Checkbox('My second Checkbox!')],
         
          
          ]   

tab2_layout = [[sg.T('Use this page to:')],   
               [sg.T('    -Create a CC from a CA')], 
               [sg.T('    -Remove header info from a SOW to give to another SOW')], 
               [sg.T('    -Copy tables from one SOW to another')], 
               [sg.Radio('CA to CC', "RADIO", default=True, key='-CAtoCC-', enable_events=True), sg.Radio('Remove Customer Info', "RADIO", key='-RemoveCust-', enable_events=True), sg.Radio('Copy Tables', "RADIO", key='-Tables-', enable_events=True)],
               [sg.In(key='in1')],
               [sg.In(key='in2')],
               [sg.Checkbox('Header',disabled = True, key='-Head-'),sg.Checkbox('Hardware',disabled = True, key='-Hard-'),sg.Checkbox('Software', disabled = True, key='-Soft-'),sg.Checkbox('Calibration', disabled = True, key='-Cal-'),sg.Checkbox('Deliverables', disabled = True, key='-Deli-')],

               
               ]    

layout = [[sg.TabGroup([[sg.Tab('Tab 1', tab1_layout, key='Tab 1'), sg.Tab('Tab 2', tab2_layout, key='Tab 2')]], key='tab')],   
          [sg.Button('Create'), sg.Button('Clear'), sg.Button('Quit')]
          ]   

tableNames = ['Header', 'Hardware', 'Software', 'Calibration', 'Deliverables']
tableKeys = ['-Head-', '-Hard-', '-Soft-', '-Cal-', '-Deli-']

# Create the window
window = sg.Window('SOW and CA Creator', layout)
 
try:
   
    # Display and interact with the Window using an Event Loop
    while True:
        event, values = window.read()      
        
        
        if values['-Tables-'] == True:
            for i in tableKeys  :
               window[i].Update(disabled = False)
               continue

        if values['-Tables-'] == False:
            for i in tableKeys  :
                window[i].Update(disabled = True)
                continue

        if event == 'Create' and values['-in1-'] != '' and values['-in2-'] != '' and values['tab'] == 'Tab 2' and values['CAtoCC']:
            pass


       # See if user wants to quit or window was closed
        if event in (sg.WINDOW_CLOSED, 'Quit' ):
            window.close()
            break
        


except Exception as e:
    window.close()
    tb = traceback.format_exc()
    sg.Print(f'An error happened.  Here is the info:', e, tb)
    sg.popup_error(f'AN EXCEPTION OCCURRED!', e, tb)

question from:https://stackoverflow.com/questions/65887955/i-am-having-a-nonetype-error-on-exiting-gui

Answer 1

Root cause for this issue

event, values = window.read()

when window close button clicked, you may get None, None for event, values.

Then if you use values[key] for values is None, then you will get

TypeError: 'NoneType' object is not subscriptable

So always put statement to check sg.WINDOW_CLOSEDafter previous statement immediately, like

while True:
    event, values = window.read()
    if event == sg.WINDOW_CLOSED:
        break

    ...

    print(event, values)

window.close()