Python - tkinter Treeview not updating integer variable

Question

The first set of code works. It displays the updating variable. However, in the second code, when I put the variable in a Treeview widget instead, the variable just stays on 0 and does not update. How come this works with the label but not with treeview? What is the easiest way to fix this?

First (works):

from tkinter import *
from tkinter import ttk
import threading
import time

def fun():
    for i in range(10):
        var.set(var.get() + 1)
        time.sleep(.5)

t = threading.Thread(target=fun)

root = Tk()

var = IntVar()
var.set(0)

mainframe = ttk.Frame(root)
mainframe.grid(column = 0, row = 0)
label = ttk.Label(mainframe, textvariable=var)
label.grid(column = 0, row = 0)

t.start()
root.mainloop()

Second (does not work):

from tkinter import *
from tkinter import ttk
import threading
import time

def fun():
    for i in range(10):
        var.set(var.get() + 1)
        time.sleep(.5)

t = threading.Thread(target=fun)

root = Tk()

var = IntVar()
var.set(0)

mainframe = ttk.Frame(root)
mainframe.grid(column = 0, row = 0)

tree = ttk.Treeview(mainframe, columns = ('number'), height = 1)

tree.insert('', 'end', text = 'Number', values = var.get())
tree.grid(column=0, row=0)

t.start()
root.mainloop()

Pratik Kumar · Accepted Answer · 2018-02-21 03:41:13Z

1

modify fun to :

def fun():
    for i in range(10):
        var.set(var.get() + 1)
        x = tree.get_children()
        tree.item(x, text = 'Number', values = var.get())
        time.sleep(.5)

The get_children method returns a list of tuples item IDs, one for each child of the tree. With tree.item then update the child with the required id.

In the second program along with the variable var, you also have to update the child of the tree

edited Feb 21, 2018 at 3:41

answered Feb 21, 2018 at 3:33

Pratik Kumar

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3 Comments

AndrewK Over a year ago

Thanks. How come the value doesn't update automatically like the first example?

AndrewK Over a year ago

How come i have to update each child of the tree when in the first example has the label changing automatically? When I receive a new piece of data from my streaming data source I was hoping to not have to update all the children as many of the values may not have changed.

Pratik Kumar Over a year ago

@AndrewK, whatever you insert into a tree automatically makes it a child of the tree. this may help for better understanding.

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