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I have a script that continuously updates numbers on a text file in the same directory. I made a GUI using tkinter to display these numbers. I'm having a hard time getting the GUI to update the numbers in real time. It will display the numbers as they were when the GUI first started, but will not update the display as the text file changes. Here's some basic code to demonstrate:

def read_files(file, line):
    old = open(f'{file}.txt', 'r').readlines()[line]
    new = old.replace('\n', '')
    return new

number = read_files('Statistics', 0)
number_label = Label(frame1, text=f'{number}')
number_label.grid(row=0, column=0)

The above code shows the number from the text file as it was when the GUI first opened. However, it does not update the number as its value in the text file changes. I did some reading around and also tried the following:

def read_files(file, line):
    old = open(f'{file}.txt', 'r').readlines()[line]
    new = old.replace('\n', '')
    return new

number = read_files('Statistics', 0)
number_label = StringVar()
number_label.set(number)
number_display = Label(frame1, text=f'{number_label.get()}')
number_display.grid(row=0, column=0)

This has the same effect. It shows the value retrieved from the text file at the moment the GUI was opened, but does not update it as the text file is updated. Any help is appreciated.

WTB Helbreath
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  • Have you tried using a tkinter loop? Look at [this](https://stackoverflow.com/a/459131/11106801). – TheLizzard Mar 14 '21 at 22:52
  • I just tried to stick it in a while loop with a root.update() at the end and that did not solve the issue. The value remains static. – WTB Helbreath Mar 14 '21 at 23:27
  • Post the code with the `while` loop please. Also using `.after()` is better but using `.update()` is fine – TheLizzard Mar 14 '21 at 23:30
  • The code is essentially the exact same as above except it is entirely nested in a while loop with root.update() inside of and at the end of the loop. I tried changing it to root.after(1000) with same results. – WTB Helbreath Mar 14 '21 at 23:33

1 Answers1

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Since there is no complete code, take a look at this example:

from tkinter import *

root = Tk()

def update_gui():
    number = read_files('Statistics', 0) # Call the function
    number_display.config(text=number) # Change the text of the label, also same as text=f'{number}'
    root.after(1000,update_gui) # Repeat this function every 1 second

def read_files(file, line):
    old = open(f'{file}.txt', 'r').readlines()[line]
    new = old.replace('\n', '')
    return new

number_display = Label(root) # Empty label to update text later
number_display.grid(row=0, column=0)

update_gui() # Initial call to the function

root.mainloop()

Here the label is created outside the function but the text is not given, but inside the function we are repeating the function every 1 second, with after, and changing the text of the label with config method. I have avoided the use of StringVar() as it's of no use here, you can just store it in a normal variable and use it.

Here is a plagiarized look at how after should be used:

def after(self, ms, func=None, *args):
    """Call function once after given time.

    MS specifies the time in milliseconds. FUNC gives the
    function which shall be called. Additional parameters
    are given as parameters to the function call.  Return
    identifier to cancel scheduling with after_cancel."""
Delrius Euphoria
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  • Actually, it is starting to error out at times. Every once in a while it throws a: old = open(f'{file}.txt', 'r').readlines()[line].replace(f'{text}: ', '') IndexError: list index out of range I increased the time from 1 second to a longer time and this seems to help, but eventually the error occurs again. Any ideas? – WTB Helbreath Mar 15 '21 at 03:19
  • @WTBHelbreath Hmmm, well you are indexing it with `[line]` error says that it is out of range. You are passing `0` as the `line` and if you get error still, it means that the list is empty and your trying to read from it, hence the error(empty file I assume). Try to use `try`/`except` to ignore the error. – Delrius Euphoria Mar 15 '21 at 10:18