Checkbutton Value Constant

I am trying to set a value to the checkbutton by passing 1 or 0 (as an integer) to this function. However, there is no change in state of checkbutton. Please help. def change_O

Solution 1:

Probably problem is because CheckVar1 is local variable and it doesn't exist when you leave function.

Use global variable and it will work.

from tkinter import *

# --- functions ---

def change_On_Off_state(*args):
    CheckVar1.set(*args)
    OnOff = Checkbutton(root, text="On", variable=CheckVar1, onvalue=1, offvalue=0, height=1, width=10, anchor=W, bg='Light Blue')
    OnOff.grid(row=4, column=2, padx=10, sticky=W)
    #CheckVar1.trace_variable("w", On_Off_state)

# --- main ----

root = Tk()

CheckVar1 = IntVar() # global

change_On_Off_state(1)

# "start the engine"
root.mainloop()

I think you don't have to create new Checkbutton() to change state. Create Checkbutton and CheckVar only once and use only `CheckVar1.set(...) many times.

from tkinter import *

# --- functions ---defchange_On_Off_state(*args):
    CheckVar1.set(*args)
    #CheckVar1.trace_variable("w", On_Off_state)defchange_on_button_press():
    if CheckVar1.get() == 1:    
        CheckVar1.set(0)
    else:
        CheckVar1.set(1)

# --- main ----

root = Tk()

# create only once
CheckVar1 = IntVar() # global# create only once
OnOff = Checkbutton(root, text="On", variable=CheckVar1, onvalue=1, offvalue=0)
OnOff.grid()

# use many times
change_On_Off_state(1)

# use button to on/off checkbutton
btn = Button(root, text="On / Off", command=change_on_button_press)
btn.grid()

# "start the engine"
root.mainloop()