Python tkinter: Text widget doesn't change text immidiately-CodePudding

I have a tk.Text() widget and a button. When the button is clicked, I want to change the text in the Text widget, then conduct a lengthy job. Here is code snippet from the button command function:

price_text.delete("1.0", tk.END)
price_text.insert(tk.END, 'PLEASE WAIT..')  
result = self.the_lengthy_job()

However, the 'PLEASE WAIT..' message just won't show up until self.the_length_job() returns. Is it possible to get it show before the_length_job() starts?

---EDIT--- Here is more code:

import tkinter as tk
import pandas_datareader as web

class GUI:
    def __init__(self):
        self.root = tk.Tk()
        self.root.geometry("800x480")
        self.price_text = tk.Text(self.root)
        self.price_text.grid(row=0, column=0, )

        tk.Button(self.root, text="Get", command=self.do_get).grid(row=1, column=0)
        self.root.mainloop()

    def do_get(self):
        self.price_text.delete("1.0", tk.END)
        self.price_text.insert(tk.END, "PLEASE WAIT..")
        result = self.lengthy_job()

    def lengthy_job(self):
        tickers = ["GOOG", "AAPL", "MSFT", "IBM", "F", "AMZN", "NVDA", "NFLX", "DISH", "BABA", "JD", "SHOP", "PDD", "CSCO", "AMD", "INTC", "TXN", "MU", "QCOM"]
        return web.DataReader(tickers, 'yahoo', start="2020-1-1", end="2020-1-31")

GUI()

In this example, "PLEASE WAIT.." only shows up after lengthy_job() is done.

CodePudding user response：

The problem here is that the window is not being updated after the text is inserted. This is because events are only processed after a callback returns.

To force the window to process the events before the callback returns, you can call self.root.update_idletasks() (at CoolCloud's suggestion, you shouldn't use update() unless it's absolutely necessary). Here is what the do_get() should look like:

def do_get(self):
    self.price_text.delete("1.0", tk.END)
    self.price_text.insert(tk.END, "PLEASE WAIT..")
    self.root.update_idletasks() # Update the window here
    result = self.lengthy_job()