Retrieving and using a tkinter combobox selection

Question

I am putting together a GUI for a customized calculator that automatically converts certain units of measurements into other units of measurement.

I want to return the actual text selected so I can write if statements from whatever the user selected. How do I get python to return the actual value instead of what I am getting now?

Whenever I test this code I receive the following:

VirtualEvent event x=0 y=0

Below is the portion of the code that I am attempting to use for this process. For the example code below I want the user to be able to input area as either acres or square feet. I then plan to write an if statement to convert whatever they selected into square kilometers (code for input of numbers not included in this example in an attempt to keep this post concise).

import tkinter as tk
from tkinter.ttk import *

master = tk.Tk()
master.title("Gas Calculator")
v = tk.IntVar()
combo = Combobox(master)

def callback(eventObject):
    print(eventObject)

comboARU = Combobox(master)
comboARU['values']= ("Acres", "Ft^2")
comboARU.current(0) #set the selected item
comboARU.grid(row=3, column=2)
comboARU.bind("<<ComboboxSelected>>", callback)

master.mainloop()

Please let me know if I can expand on anything. I am still new at python so I wouldnt be surprised at all if this is just a simple syntax thing that I am missing.

Solution 1

You should retrieve the content of comboARU using get() function as follows:

def callback(eventObject):
    print(comboARU.get())

Solution 2

you can retrieve the value of the Combobox directly off the event object by eventObject.widget.get() .

import tkinter as tk
from tkinter.ttk import *

master = tk.Tk()
master.title("Gas Calculator")
v = tk.IntVar()
combo = Combobox(master)

def callback(eventObject):
    # you can also get the value off the eventObject
    print(eventObject.widget.get())
    # to see other information also available on the eventObject
    print(dir(eventObject))

comboARU = Combobox(master)
comboARU['values']= ("Acres", "Ft^2")
comboARU.current(0) #set the selected item
comboARU.grid(row=3, column=2)
comboARU.bind("<<ComboboxSelected>>", callback)

master.mainloop()

Solution 3

If you want be get be able to use the default value set with comboAru.current(0), event handling doesn't work, I find it works best to get the combobox value when pressing an OK button, and if you want to get the value and use it afterwards, it's best to create a class, avoiding global variables (because the class instance and it's variables remain after tkinter window is destroyed) (based on answer https://stackoverflow.com/a/49036760/12141765).

import tkinter as tk     # Python 3.x
from tkinter import ttk

class ComboboxSelectionWindow():
    def __init__(self, master):
        self.master=master
        self.entry_contents=None
        self.labelTop = tk.Label(master,text = "Select one of the following")
        self.labelTop.place(x = 20, y = 10, width=140, height=10)
        self.comboBox_example = ttk.Combobox(master,values=["Choice 1","Second choice","Something","Else"])
        self.comboBox_example.current(0)
        self.comboBox_example.place(x = 20, y = 30, width=140, height=25)

        self.okButton = tk.Button(master, text='OK',command = self.callback)
        self.okButton.place(x = 20, y = 60, width=140, height=25)

    def callback(self):
        """ get the contents of the Entry and exit
        """
        self.comboBox_example_contents=self.comboBox_example.get()
        self.master.destroy()

def ComboboxSelection():

    app = tk.Tk()
    app.geometry('180x100')
    Selection=ComboboxSelectionWindow(app)
    app.mainloop()

    print("Selected interface: ", Selection.comboBox_example_contents)

    return Selection.comboBox_example_contents

print("Tkinter combobox text selected =", ComboboxSelection())