Formatting user entry in Tkitner Entry box using locale with event

We can format the inputs by using different events and one common requirement is formatting to local system. We are using locale library.

import locale

Here is the code to format the input as entered by user and on lost focus or once the focus is moved out of the input box the data is formatted. The required format can be changed based by using setlocal().

locale.setlocale(locale.LC_ALL, 'en_US.utf8')# USA

Function show_format()

This function is triggered once the input box lost the focus and the code to format the input is kept here. The triggering event can be changed .

def show_format(*args):
    e1_str.set(locale.format_string("%.2f", float(e1.get()), grouping=True))

Here e1_str is the string variable connected to entry option. So we used set() option of string variable to assign value to entry box.

Triggering the event to execute the function

Here we used on focus out event to trigger the function, however this event can be changed to any other required event.

e1.bind("<FocusOut>",show_format) # when tab is pressed
#e1.bind("<KeyRelease>",show_format) # when key is released

Output

Data entered is 12345678.456

#locale.setlocale(locale.LC_ALL, 'de_DE.utf8')# German

locale.setlocale(locale.LC_ALL, 'en_US.utf8')# USA

Without using locale library

Inside the function show_format() we can use this line to get string formatting.

e1_str.set("{:,}".format(int(e1.get())))

Full code is here

import tkinter as tk
import locale
#locale.setlocale(locale.LC_ALL, 'de_DE.utf8')# German
locale.setlocale(locale.LC_ALL, 'en_US.utf8')# USA
my_w = tk.Tk()
my_w.geometry("250x100") 
font1=('Times',18,'bold')	
sv = tk.StringVar() # String variable 
def show_format(*args):
    #e1_str.set("{:,}".format(int(e1.get())))
    e1_str.set(locale.format_string("%.2f", float(e1.get()), grouping=True))
e1_str=tk.StringVar() # string variable   
e1 = tk.Entry(my_w,font=font1,width=13,textvariable=e1_str)
e1.grid(row=1,column=1,padx=18,pady=5)
b1=tk.Button(my_w,text='Testing')
b1.grid(row=1,column=2)
e1.bind("<FocusOut>",show_format) # when tab is pressed
my_w.mainloop()  # Keep the window open

We can use on key release event and then format every 4^th position. Check how the cursor position is collected and repositioned.
Format with thousand place

from tkinter import *
import tkinter as tk
my_w = tk.Tk()
my_w.geometry("350x100") 
font1=('Times',18,'bold')	
sv = tk.StringVar() # String varible 
def show_format(*args):
    position = e1.index(INSERT) # getting cursor position
    if((position % 4)==0):
        e1.icursor(position+1) # shift cursor one position
    x=e1_str.get().replace(',','')
    e1_str.set("{:,}".format(float(x)))
  
e1_str=tk.StringVar() # string variable   
e1 = tk.Entry(my_w,font=font1,width=20,textvariable=e1_str)
e1.grid(row=1,column=1,padx=18,pady=5)
#e1.bind("<FocusOut>",show_format) # when tab is pressed
e1.bind("<KeyRelease>",show_format) # when key is released
my_w.mainloop()  # Keep the window open

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Subhendu Mohapatra

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Formatting tkinter Entry

Function show_format()

Triggering the event to execute the function

Output

Without using locale library

Subhendu Mohapatra