How to pass a variable from __init__ of one class to another at the click of a button in a tkinter program with multiple frames?

Question

I want to pass the value stored in self.pin, which we get from the user through entry() in StartPage to the __init__ method of Options class but only when I click the submit button. Also this must be noted that there are multiple pages and I have used tkraise() to raise one page over the other. Explanation will be appreciated as I'm new to tkinter and oop. My whole code is given below:

import tkinter as tk
from tkinter import font  as tkfont
from tkinter import messagebox

class SampleApp(tk.Tk):

    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)

        self.title_font = tkfont.Font(family='Courier New', size=18, weight="bold")

        container = tk.Frame(self)
        container.pack(side="top", fill="both", expand=True)
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        self.frames = {}
        for F in (StartPage, PageOne, PageTwo, PageThree, PageFour, Options):
            page_name = F.__name__
            frame = F(parent=container, controller=self)
            self.frames[page_name] = frame

            frame.grid(row=0, column=0, sticky="nsew")

        self.show_frame("StartPage")

    def show_frame(self, page_name):
        frame = self.frames[page_name]
        frame.tkraise()


class StartPage(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="Enter 4 digit pin", font=controller.title_font, fg="red")
        label.pack(side="top", fill="x", pady=10)

        self.pin = tk.Entry(self, bd = 4, relief="groove", show="*", font=20, justify='center')
        # self.pin="786125"
        self.pin.pack()

        submit = tk.Button(self, text="Submit", width=12,font=tkfont.Font(size=12),command=lambda: [controller.show_frame("Options")], cursor="hand2")
        submit.pack()


class Options(StartPage):

    def __init__(self, parent, controller):
        # StartPage.__init__(self, parent, controller)
        # print(self.pin.get())
        tk.Frame.__init__(self, parent)
        self.controller = controller
        f1=tk.Frame(self)
        f1.pack()
        f2=tk.Frame(self)
        f2.pack(side="bottom")
        button1 = tk.Button(f1, text="Balance Inquiry",relief="flat", padx=30, justify='left', cursor="hand2", fg="red", font=tkfont.Font(size=10),
                           command=lambda: controller.show_frame("PageOne"))
        button1.pack(side="left")

        button2 = tk.Button(f1, text="Deposit",relief="flat", padx=50, justify='right', cursor="hand2", fg="red", font=tkfont.Font(size=10),
                           command=lambda: controller.show_frame("PageTwo"))
        button2.pack(side="left")

        button3 = tk.Button(f2, text="Withdraw",relief="flat", padx=50, justify='left', cursor="hand2", fg="red", font=tkfont.Font(size=10),
                           command=lambda: controller.show_frame("PageThree"))
        button3.pack(side="left")

        button4 = tk.Button(f2, text="Pin Change",relief="flat", padx=50, justify='right', cursor="hand2", fg="red", font=tkfont.Font(size=10),
                           command=lambda: controller.show_frame("PageFour"))
        button4.pack(side="left")

Answer 1

Personally I would keep the value stored in the controller and then access it from the other pages. Here is a modified version of your code that can access the stored pin.

This is done by adding a command to the buttons lambda and saving the entry value to the controller.

import tkinter as tk
from tkinter import font  as tkfont
from tkinter import messagebox

class SampleApp(tk.Tk):
    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        self.pin_stored = ""
        self.title_font = tkfont.Font(family='Courier New', size=18, weight="bold")

        container = tk.Frame(self)
        container.pack(side="top", fill="both", expand=True)
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        self.frames = {}
        for F in (StartPage, Options):
            page_name = F.__name__
            frame = F(parent=container, controller=self)
            self.frames[page_name] = frame
            frame.grid(row=0, column=0, sticky="nsew")
        self.show_frame("StartPage")

    def show_frame(self, page_name):
        frame = self.frames[page_name]
        frame.tkraise()


class StartPage(tk.Frame):
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="Enter 4 digit pin", font=controller.title_font, fg="red")
        label.pack(side="top", fill="x", pady=10)
        self.pin = tk.Entry(self, bd = 4, relief="groove", show="*", font=20, justify='center')
        self.pin.pack()

        submit = tk.Button(self, text="Submit", width=12,font=tkfont.Font(size=12), command=lambda: [controller.show_frame("Options"), self.store_pin()], cursor="hand2")
        submit.pack()

    def store_pin(self):
        print("test")
        self.controller.pin_stored = self.pin.get()


class Options(StartPage):
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        f1=tk.Frame(self)
        f1.pack()
        f2=tk.Frame(self)
        f2.pack(side="bottom")
        button1 = tk.Button(f1, text="Balance Inquiry",relief="flat", padx=30, justify='left', cursor="hand2", fg="red", font=tkfont.Font(size=10),
                           command=lambda: controller.show_frame("PageOne"))
        button1.pack(side="left")

        button2 = tk.Button(f1, text="Deposit",relief="flat", padx=50, justify='right', cursor="hand2", fg="red", font=tkfont.Font(size=10),
                           command=lambda: controller.show_frame("PageTwo"))
        button2.pack(side="left")

        button3 = tk.Button(f2, text="Withdraw",relief="flat", padx=50, justify='left', cursor="hand2", fg="red", font=tkfont.Font(size=10),
                           command=lambda: controller.show_frame("PageThree"))
        button3.pack(side="left")

        button4 = tk.Button(f2, text="Pin Change",relief="flat", padx=50, justify='right', cursor="hand2", fg="red", font=tkfont.Font(size=10),
                           command=lambda: controller.show_frame("PageFour"))
        button4.pack(side="left")

        tk.Button(self, text="print stored pin", command=self.print_pin).pack()

    def print_pin(self):
        print(self.controller.pin_stored)


if __name__ == "__main__":
    SampleApp().mainloop()