Simple GUI Login System

login_gui.py

# reference (https://pythonprogramming.net/change-show-new-frame-tkinter/)

import tkinter as tk

# window
class LoginApp(tk.Tk):
	# constructor
	def __init__(self, *args, **kwargs):
		tk.Tk.__init__(self, *args, **kwargs)
		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 (LoginPage, HomePage):
		    frame = F(container, self)
		    self.frames[F] = frame
		    frame.grid(row=0, column=0, sticky="nsew")
		self.show_frame(LoginPage)

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

# frame
class LoginPage(tk.Frame):
	correctPassword = "password1234"

	# constructor
	def __init__(self, parent, controller):
		tk.Frame.__init__(self,parent)
		title = tk.Label(self, text="Login")
		title.pack(pady=10,padx=10)

		errorMsg = tk.StringVar()
		errorLabel = tk.Label(self, textvariable=errorMsg)
		errorLabel.pack(pady=10,padx=10)

		enteredPassword = tk.StringVar()
		passwordEntry = tk.Entry(self, show="*", textvariable=enteredPassword)
		passwordEntry.pack()

		loginBtn = tk.Button(
			self, text="Login",
			command=lambda: self.validatePassword(enteredPassword.get(), errorMsg)
		)
		loginBtn.pack()

	def validatePassword(self, password, errorMsg):
		if password == self.correctPassword:
			app.show_frame(HomePage)
		else:
			errorMsg.set("Invalid password!")

# frame
class HomePage(tk.Frame):
	# constructor
	def __init__(self, parent, controller):
		tk.Frame.__init__(self,parent)
		title = tk.Label(self, text="Home Page (do whatever here!)")
		title.pack(pady=10,padx=10)

app = LoginApp()
app.mainloop()