How do you update a label every time text is typed into a textbox, using tkinter

I’m trying to create an app where a part of it involves a label that dynamically changes and displays the number of characters typed within the textbox every time it gets updated. I couldn’t find any information regarding this and unsure whether this is even possible.

Answer

If you want a simpler solution that requires a bit more work by the caller, look at this:

import tkinter as tk

def callback(event):
    # After 1 ms call `_callback`
    # That is to make sure that tkinter has handled the keyboard press
    root.after(1, _callback)

def _callback():
    # The `-1` is there because when you have `text_widget.get(..., "end")`
    # It adds a "n" character at then end
    number_of_chars = len(text_widget.get("1.0", "end")) - 1
    print(number_of_chars)

root = tk.Tk()
text_widget = tk.Text(root)
text_widget.pack()

text_widget.bind("<Key>", callback)

root.mainloop()

This basically binds all keyboard presses to the callback function. I can’t think of any way to change the text in a text widget without pressing a keyboard button.

Please note that it will only run when a key is pressed so it wouldn’t work if you called text_widget.insert or text_widget.delete (@acw1668 found that problem). It is the caller’s responsibility to call _callback just after they call .insert/.delete.