main.py

from tkinter import font
from tkcalendar import Calendar, DateEntry
import tkinter as tk

# set font options for button
FirstFont =('Helvetica', 20)

# create class for initialized gui
class app(tk.Tk):
    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        # create windows container or frame main
        frm_main = tk.Frame(self)
        frm_main.pack(side = "top", expand = True)
        frm_main.grid_rowconfigure(0, weight = 1)
        frm_main.grid_columnconfigure(0, weight = 1)

        # initiaze frame to empty array
        self.frames = {}

        # create different window iteration
        for F in (mainpage, insert_data, export_data):
            frame = F(frm_main, self) # need explanation in cheat sheet
            # initiaze first window
            self.frames[F] = frame
            frame.grid(row = 0, column = 0, sticky ="nsew")
        self.show_frame(mainpage)

    # to display the current frame passed as
    # parameter
    def show_frame(self, cont):
        frame = self.frames[cont]
        frame.tkraise()

# first window frame startpage

class mainpage(tk.Frame):
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)

        # button for main page
        btn_export = tk.Button(self, text ="Export Data", font = FirstFont, command = lambda : controller.show_frame(export_data))
        btn_insert = tk.Button(self, text ="Insert Data", font = FirstFont, command = lambda : controller.show_frame(insert_data))

        # putting the grid in its place by using
        # grid
        #btn_insert.grid(row = 0, padx = 10, pady = 10, sticky ="ew")
        #btn_export.grid(row = 1, padx = 10, pady = 10, sticky ="ew")
        btn_insert.pack(fill='both', expand=True)
        btn_export.pack(side='bottom', fill='both', expand=True)



class insert_data(tk.Frame):
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)

        # create calender dropdown menu
        cal_input = DateEntry(
            self,
            width = 12,
            borderwidth = 2,
            year = 2020,
            background = 'blue'
        )

        # create dropdown menu
        variable = tk.StringVar(self)
        variable.set('Weekdays')
        dropdown_date = tk.OptionMenu(
            self,
            variable,
            'Weekend',
            'Weekdays',
        )

        # create input widget
        ent_activity = tk.Entry(
            self,
            width = 30
        )

        # create button for 2nd page
        btn_data = tk.Button(
            self,
            text = 'Add data',
            width = 25

        )

        # create button for return to main menu
        btn_back = tk.Button(
            self,
            text = 'Back',
            width = 25,
            background = 'red',
            command = lambda : controller.show_frame(mainpage)
        )

        # put widget on grid
        btn_data.grid(row = 3, column = 1, padx = 10, pady = 10)
        btn_back.grid(row = 4, column = 1, padx = 10, pady = 5)
        cal_input.grid(row = 1, column = 1, padx = 10, pady = 5, sticky = 'ew')
        dropdown_date.grid(row = 2, column = 1, padx = 10, pady = 5, sticky ='ew')
        ent_activity.grid(row = 0, column = 1, padx = 10, pady = 5)

class export_data(tk.Frame):
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)

        # create calender dropdown menu
        cal_export = DateEntry(
            self,
            width = 12,
            borderwidth = 2,
            year = 2020,
            background = 'blue'
        )

        # export button
        btn_export_data = tk.Button(
            self,
            text = 'Export Data',
            width = 25,

        )

        # back button to main menu
        btn_back = tk.Button(
            self,
            text = 'Back',
            width = 25,
            background = 'red',
            command = lambda : controller.show_frame(mainpage)
        )



        # put widget on grid
        cal_export.grid(row = 0, column = 0, padx = 10, pady = 5, sticky = 'ew')
        btn_export_data.grid(row = 1, padx = 10, pady = 15)
        btn_back.grid(row = 2, padx = 10, pady = 10)



# Driver Code
app1 = app()
app1.mainloop()