Tkinter window does not update correctly when running - python-3.x

Question

I'm trying to make a Tkinter window show updated data but it only pops up after 13 seconds with just the last value. I want it to pop up and change the values on screen. Mind you, the big goal of this code is to take data from a database (which updates every 3 seconds) and show the data onscreen, while running continuously, so if the answer could include some pointers on the "after" or "update" functions it would be greatly appreciated!
Here is what I have so far.
from tkinter import *
import time
class GUI(Tk):
def __init__(self, *args, **kwargs):
Tk.__init__(self, *args, **kwargs)
Tk.wm_title(self, "Main Window")
self.container = Frame(self)
self.container.pack(side=TOP, fill=BOTH, expand=TRUE)
self.container.grid_rowconfigure(0, weight=1)
self.container.grid_columnconfigure(0, weight=1)
self.frames = {}
self.frame = StartPage(self.container, self)
self.frames[StartPage] = self.frame
self.frame.grid(row=0, column=0, sticky=NSEW)
self.show_frame(StartPage)
def show_frame(self, controller):
frame = self.frames[controller]
frame.tkraise()
class StartPage(Frame):
def __init__(self, parent, controller):
Frame.__init__(self, parent)
self.label = Label(self, text="Current ID:\n")
self.label.pack(padx=10, pady=10)
self.data_label = Label(self)
self.data_label.pack()
self.update_data()
def update_data(self):
var1 = StringVar()
for i in range(10):
var1.set(str(i))
self.data_label.config(text=str(i))
time.sleep(1)
main = GUI()
main.mainloop()

Answer 1

I can give you a partial answer. The reason you don't see any updates is that time.sleep() suspends the process and does not allow for tkinter to repaint the window.
You don't use the label textvariable correctly. Specify it in the label and the label will change as you change the textvariable.
You use both pack and grid at the same time which may cause problems.
I have not used after() in a class before so I don't know how to work it, but this example should give you some pointers. I'm keeping console printouts in the code so I can see what it does.
from tkinter import *
import time
class GUI(Tk):
def __init__(self, *args, **kwargs):
Tk.__init__(self, *args, **kwargs)
Tk.wm_title(self, "Main Window")
self.container = Frame(self)
self.container.pack(side=TOP, fill=BOTH, expand=TRUE)
self.frames = {}
self.frame = StartPage(self.container, self)
self.frames[StartPage] = self.frame
self.frame.pack(side=TOP, fill=BOTH, expand=TRUE)
self.show_frame(StartPage)
def show_frame(self, controller):
frame = self.frames[controller]
frame.tkraise()
frame.update_data()
print('Done')
class StartPage(Frame):
def __init__(self, parent, controller):
Frame.__init__(self, parent)
self.parent = parent
self.label = Label(self, text="Current ID:\n")
self.label.pack(padx=10, pady=10)
self.var1 = StringVar()
self.data_label = Label(self, textvariable=self.var1)
self.data_label.pack()
self.update_idletasks() # Calls all pending idle tasks
def update_data(self):
if not self.var1.get(): self.var1.set('0')
iteration = int(self.var1.get())
print('iteration', iteration)
if iteration < 3:
iteration = iteration + 1
self.var1.set(str(iteration))
self.update_idletasks() # Calls all pending idle tasks
time.sleep(1)
self.update_data()
main = GUI()
main.mainloop()
You will have to research after() yourself as I can't help you there.