How do I add new options, and then read the new selected option in a python tkinter optionMenu?

Question

With the code I currently have, when the program starts, I can select from 3 options, and have that option printed to the console. I can also have text entered into the text entry, be added to the optionMenu list by pressing the button.

By adding the new option, it breaks the optionMenu, and I am no longer able to get the selected option from the optionMenu.

I have tried looking through tkinter documentation (the little I could find), but have not found info relating to my problem.

import tkinter

category_list = ['Option A', 'Option B','Option C']

def add_To_List():
    entry = entry_Right.get()
    if entry not in category_list:
        option_Left_StringVar.set('')

        menu_left = option_Left["menu"]
        menu_left.delete(0, "end")
        category_list.append(entry)

        for choice in category_list:
            menu_left.add_command(label=choice, 
command=tkinter._setit(option_Left_StringVar, choice))

def option_Left_Function(selection):
    print(selection)

#----GUI----

root = tkinter.Tk()

frame_Left = tkinter.Frame(root)
frame_Left.grid(column=0, row=0, sticky='w')


option_Left_StringVar = tkinter.StringVar(frame_Left)
option_Left = tkinter.OptionMenu(frame_Left, option_Left_StringVar, 
*category_list, command=option_Left_Function)
option_Left.grid(column=0, row=0, sticky='w')


frame_Right = tkinter.Frame(root)
frame_Right.grid(column=1, row=0, sticky='e')

entry_Right = tkinter.Entry(frame_Right)
entry_Right.grid(column=1, row=0, sticky='w')

button_Right = tkinter.Button(frame_Right, text='Add to list', 
command=add_To_List)
button_Right.grid(column=2, row=0, sticky='w')

root.mainloop()

The furthest I was able to come (as you see in the code above), was to add a new option to the optionMenu, but this doesn't help when I cannot then access the selection of the optionMenu in the code.

I would really appreciate help on this issue, thanks.

Answer 1

You have to add option_Left_Function as third argument

command=tkinter._setit(option_Left_StringVar, choice, option_Left_Function)

Using print(tkinter.__file__) you can get path to source code and you can see this in this file.

---

BTW: you don't have to delete old items. You can add only new item.

def add_To_List():
    entry = entry_Right.get()
    if entry not in category_list:
        option_Left_StringVar.set('')

        menu_left = option_Left["menu"]
        menu_left.add_command(label=entry, 
                  command=tkinter._setit(option_Left_StringVar, entry, option_Left_Function))

        category_list.append(entry)