Tkinter set new value for labels

Question

How can I set a new value to a label in tkinter? I have this code, but it's only show a blank window Sorry for my english and, please, if you can, explain. (I'm new to programming) Thank you for your attention!

import os, time, tkinter, urllib
from tkinter import *
from urllib.request import *
from urllib.error import *

class App:
    def __init__(self, master):
        v = StringVar()
        start_time = time.time()
        frame = Frame(master)
        frame.pack()
        self.label = Label(frame, textvariable=v).pack()
        if self.internet_on() == 1:
            v.set = "Internet is online"
            start_time = time.time()
        else:
            v.set = "Internet is offline!  Downtime: " + str(time.time() - start_time)


    def internet_on(self):
        try:
            response=urllib.request.urlopen('http://www.google.com.br',timeout=1)
            return True
        except urllib.error.URLError as err: pass
        return False            
top = tkinter.Tk()
app = App(top)

top.mainloop()

Answer 1

The simplest method is to do the updating in the method forgetting returning booleans and using root.after:

from tkinter import *
import  urllib.request
import urllib.error

class App(Frame):
    def __init__(self, master):
        Frame.__init__(self, master)
        self.start_time = time.time()
        self.label = Label(root, text="Starting.....")
        self.label.pack()
        self.internet_on()

    def internet_on(self):
        try:
            urllib.request.urlopen('http://www.google.com.br', timeout=1)
            self.label.config(text="Internet is online")
            self.start_time = time.time()
        except urllib.error.URLError:
            self.label.config(text="Internet is offline!  Downtime: " + str(time.time() - self.start_time))
        root.after(1000, self.internet_on)

root = tkinter.Tk()
app = App(root)
app.pack()

Answer 2

v.set is a method, you are not supposed to write over it as -

v.set = "Internet is online"

You are supposed to call it and pass the string you want to write as argument -

v.set("Internet is online")

And

v.set("Internet is offline!  Downtime: " + str(time.time() - start_time))

---

As noted in the comments, you can also directly set the text value for the label , and then use label.config() to change the text. Example -

import os, time, tkinter, urllib
from tkinter import *
from urllib.request import *
from urllib.error import *

class App:
    def __init__(self, master):
        start_time = time.time()
        frame = Frame(master)
        frame.pack()
        if self.internet_on() == 1:
            self.label = Label(frame, text="Internet is online")
            self.label.pack()
            start_time = time.time()
        else:
            self.label = Label(frame, text="Internet is offline!  Downtime: " + str(time.time() - start_time))
            self.label.pack()


    def internet_on(self):
        try:
            response=urllib.request.urlopen('http://www.google.com.br',timeout=1)
            return True
        except urllib.error.URLError as err: pass
        return False            
top = tkinter.Tk()
app = App(top)

top.mainloop()

---

The best way to solve your requirement -

In 'internet_on', periodically checking the internet status (change the text in the label). I already tried to use while with no sucess.

Would be to use .after() method of Tk() specifying a time in milliseconds (maye something like 5000 milliseconds or so , you can decide this) and specifying the iternet_on method as second argument and then using the internet_on method update the label. Example -

import os, time, tkinter, urllib
from tkinter import *
from urllib.request import *
from urllib.error import *

class App:
    def __init__(self, master):
        start_time = time.time()
        self.master = master
        self.frame = Frame(master)
        self.frame.pack()
        self.label = Label(self.frame, text="")
        self.label.pack()
        self.start_time = time.time()


    def internet_on(self):
        try:
            response=urllib.request.urlopen('http://www.google.com.br',timeout=1)
            self.label.config(text="Internet is online")
        except urllib.error.URLError as err:
            self.label.config(text="Internet is offline!  Downtime: " + str(time.time() - self.start_time))
        self.master.after(5000,self.internet_on)          
top = tkinter.Tk()
app = App(top)
top.after(5000,app.internet_on)
top.mainloop()