Python3：TkInter

Question

I've just coded this simple program but need help with Tkinter! I want to use what the user types into the adult ticket box so i set it as global but because the user hasn't clicked the button yet the input_adult.get() only returns a blank string instead of the integer the user typed. Is there any way to get around this? Thanks in advance!!

from tkinter import *
import sys

adult_fare = 7.45
child_fare = 5.00
adult_tickets = 0


def child_Gui():
    mGui = Tk()
    labelNo = Label(mGui, text = "How many child/concession tickets do you need?").pack()
    input_child = Entry(mGui)
    input_child.pack()
    input_child.focus_set()
    b = Button(mGui, text = "GO", width = 10, command = child_travel)
    b.pack()

def adult_travel():
    print(adult_tickets)

def adult_Gui():
    global adult_tickets
    mGui = Tk()
    labelNo = Label(mGui, text = "How many adult tickets do you need?").pack()
    input_adult = Entry(mGui)
    input_adult.pack()
    input_adult.focus_set()
    b = Button(mGui, text = "GO", width = 10, command = adult_travel)
    b.pack()
    adult_tickets = input_adult.get()


def compare_sunday():
    sunday_answer = sundayEntry.get().lower()
    if sunday_answer == "yes":
        global child_fare
        global adult_fare
        adult_fare = 3.00
        child_fare = 3.00
        labelNo = Label(sundayGui, text = "Ok your traveling on a sunday. All prices will be $3.00!!").pack()
        okButton = Button(sundayGui, text = "Click here to continue", width = 40, command = adult_Gui).pack()
    elif sunday_answer == "no":
        labelNo = Label(sundayGui, text = "Ok your not traveling on a sunday.").pack()
        okButton = Button(sundayGui, text = "Click here to continue", width = 40, command = adult_Gui).pack()
    else:
        labelElse = Label(sundayGui, text = "Please type yes or no!!").pack()

sundayGui = Tk()
sundayGui.title("Travel Calculator")
label_sunday = Label(sundayGui, text = "Are you traveling on a sunday?").pack()
sundayEntry = Entry(sundayGui)
sundayEntry.pack()
sundayEntry.focus_set()
sundayB = Button(sundayGui, text = "Go", width = 10, command = compare_sunday).pack()

Answer 1

You need to call the get method in the callback for the button. This requires that you make the entry widget available globally:

def adult_Gui():
    global input_adult
    ...
    input_adult = Entry()
    ...

def adult_travel():
    adult_tickets = input_adult.get()
    print(adult_tickets)

Answer 2

I would do it like this. (There are some things here you didn't ask for, but I use as part of my boilerplate since they are pretty useful. Things like allowing [RETURN] key to work without focusing on button, etc).

import tkinter
import tkMessageBox


def get_user_input():
    popup = UserInput()
    if popup.command():
        return popup.command()
    else:
        message = 'Nothing was entered'
        tkMessageBox.showerror('Error', message)

class UserInput:
    def __init__(self):
        self.master = tkinter.Tk()
        l_text = 'Operator input here'
        self.label = Tkinter.Label(self.master, text=l_text)
        self.label.pack()

        self.textbox = tkinter.Entry(self.master, takefocus=1)
        self.textbox.pack()

        self.button = tkinter.Button(
            self.master,
            text="OK",
            command=self.command,
            default=tkinter.ACTIVE)
        self.button.pack()
        self.master.bind('<Shift-Return>', self.command)

        self.textbox.focus_set()
        self.master.mainloop()

    def command(self, event=None):
        user_input = self.textbox.get()
        if user_input == '':
            title = 'Input'
            message = 'Some input must be entered'
            tkMessageBox.showerror(title, message)
        else:
            self.master.withdraw()
            self.master.quit()
            return user_input

print (get_user_input())

Answer 3

I have modified your code slightly:

from tkinter import *
import sys

adult_fare = 7.45
child_fare = 5.00
adult_tickets = 0

def child_Gui():
    mGui = Tk()
    labelNo = Label(mGui, text = "How many child/concession tickets do you need?").pack()
    input_child = Entry(mGui)
    input_child.pack()
    input_child.focus_set()
    b = Button(mGui, text = "GO", width = 10, command = child_travel)
    b.pack()

def adult_travel():
    global adult_tickets # added
    global input_adult # added
    adult_tickets = input_adult.get() # moved from def adult_Gui()
    print(adult_tickets)

def adult_Gui():
    global adult_tickets
    global input_adult # added
    mGui = Tk()
    labelNo = Label(mGui, text = "How many adult tickets do you need?").pack()
    input_adult = Entry(mGui)
    input_adult.pack()
    input_adult.focus_set()
    b = Button(mGui, text = "GO", width = 10, command = adult_travel)
    b.pack()


def compare_sunday():
    sunday_answer = sundayEntry.get().lower()
    if sunday_answer == "yes":
        global child_fare
        global adult_fare
        adult_fare = 3.00
        child_fare = 3.00
        labelNo = Label(sundayGui, text = "Ok your traveling on a sunday. All prices will be $3.00!!").pack()
        okButton = Button(sundayGui, text = "Click here to continue", width = 40, command = adult_Gui).pack()
    elif sunday_answer == "no":
        labelNo = Label(sundayGui, text = "Ok your not traveling on a sunday.").pack()
        okButton = Button(sundayGui, text = "Click here to continue", width = 40, command = adult_Gui).pack()
    else:
        labelElse = Label(sundayGui, text = "Please type yes or no!!").pack()

sundayGui = Tk()
sundayGui.title("Travel Calculator")
label_sunday = Label(sundayGui, text = "Are you traveling on a sunday?").pack()
sundayEntry = Entry(sundayGui)
sundayEntry.pack()
sundayEntry.focus_set()
sundayB = Button(sundayGui, text = "Go", width = 10, command = compare_sunday).pack()

sundayGui.mainloop() # added

I commented the alterations. With me it prints the number (actually the string).

Answer 4

My first question is what version is your Python, 2X or 3X? if you're running Python 3X then you have to import tkinkter like this if you want to have access to Tk this is how you do it

import tkinter as tk

class YourClassName(tk.Tk))

If you're running Python 2X then you have to import tkinter like this,

import tkinter as Tk

I would try changing the import and see what happens. If this does not work I would like to see the error message's you get. Hope this helps.

Answer 5

The Entry widget must have a variable in the 'textvariable' parameter , the variable type should already be declared . Like consider adding the following 3 step process in ur code ;

Var1=IntVar() # 1.First we declare the variable as IntVar()/StringVar() for intergers & strings respectively

input_child = Entry(mGui,textvariable=var1) # 2.Now we assign the variable to a 'textvariable' parameter in the Entry widget.

var1.get() # 3. Now we get the input stored in the variable var1 using the get method .

Always the Entry widget should contain a variable & it should already be assingned as either IntVar()/StringVar() before using it as a 'textvariable' parameter inside the Entry widget .