Dialog Boxes

Note that the name of tkinter changed from "Tkinter" in Python 2.x to "tkinter" in Python 3.x.

A Dialog to Get a Value from the User

A regular problem that will arise in Python programs is getting values from the user. The code below will display a dialog box and ask the user to enter a value. The value is then printed to "Debug I/O" but it could also be set to a global and then used later in the program. The dialog has been placed into a class to keep the code organized. This is a good practice and you can save the class to a module and use it in different Python programs you create. Try this code now and play around with changing the names of the labels and buttons.

from tkinter import *

class MyDialog:

	def __init__(self, master): # called when the object is created

		self.WindowFrame = Toplevel(master) # get the window "frame"

		Label(self.WindowFrame, text="Value").pack() # add the label to the frame

		self.TheValue = Entry(self.WindowFrame) # add the text entry box for the value

		OKButton=Button(self.WindowFrame, text="OK", command=self.OKPressed) # add the "OK" button

	def OKPressed(self): # Called when the "OK" button is pressed
		print("Value inside MyDialog is "+self.TheValue.get()) # print the value
		self.ReturnedValue=self.TheValue.get() # the control will be destroyed with the window so we need to save it here.
		self.WindowFrame.destroy() # Close the parent

Then, use the code below to open the dialog and get a value from the user. Note that the code below uses "wait_window" to keep the user from interacting with other windows until they click "OK" and "destroy" this window. This makes the dialog "modal".

from tkinter import *
import Mydialog

MainWindow = Tk() # Get the MasterWindow object for Tkinter
MainWindow.withdraw() # Don't show the modeless main window

TheDialog=Mydialog.MyDialog(MainWindow) # Create the Dialog Box

MainWindow.wait_window(TheDialog.WindowFrame) # Wait until the window is closed

print("Value after returning from MyDialog: "+format(TheDialog.ReturnedValue)) 

Additional Resources:

Python Documentation: Classes

An Introduction to tkinter

Tkinter Reference: A GUI for Python

Dialog Windows in tKinter

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