Python Tkinter GUI Login

Question

I have been programming for about 4 to 5 months now and I made a login script with tkinter in python. I tried to use classes and function definitions as best as I could. To get to know them better.

I wanted to ask you all, how does this code look and is there something I should or shouldn't do the next time I code?

THANKS IN ADVANCED FOR ALL YOUR SUGGESTIONS

from tkinter import * 
import tkinter.font as font
import time


global data

data = {}

class Visual:
    def __init__(self,old_root):
        old_root.destroy()

        self.root = Tk()
        self.win_size = self.root.geometry("800x500")

        self.color = self.root.configure(bg="black")
        self.font = font.Font(size= 30)

        self.home_screen()
        # print data to check and see what is in data
        print(data)

    def home_screen(self):

        # just title on the home screen
        title = Label(self.root, text= "WELCOME USER , PLEASE LOGIN BELOW ",padx= 200,anchor= "center" ,bg="grey")
        title.place(relx= 0.5, rely= 0.0 , anchor= "n")

        # the login fields and the enter button
        self.entery()


    def entery(self):

        # a text that says "username" next to the input field
        user_text = Label(self.root, text= "USERNAME :", bg="grey")
        # the username input field
        username = Entry(self.root, width= 50)

        # a text that says "password" next to the input field
        passw_text = Label(self.root, text= "PASSWORD :", bg= "grey")
        # the password input field
        password = Entry(self.root, width= 50)

        # puts the text and the user input fields on the screen
        user_text.place(rely= 0.1, anchor= "nw")
        username.place(relx= 0.1, rely= 0.1, anchor= "nw")

        # puts the text and the user input fields on the screen
        passw_text.place(rely= 0.2,anchor= "nw")
        password.place(relx= 0.1, rely= 0.2, anchor= "nw")


        # button that is clicked when finished with inputting your login information

        submit = Button(self.root, text= "ENTER", padx= 80, pady= 10, command=lambda :Login(username_clear=username,
                                                                                        password_clear= password,
                                                                                        root= self.root,
                                                                                        user_input= username.get(),
                                                                                        passw_input= password.get()))
        submit.place(relx= 0.6, rely= 0.2, anchor= "sw")
        self.root.mainloop()

class Login:
    def __init__(self, username_clear , password_clear , root, user_input, passw_input):
        
        # clears the input fields
        username_clear.delete(0,END)
        password_clear.delete(0,END)

        self.root = root

        self.user_input = user_input
        self.passw_input = passw_input

        self.login_check()

    def login_check(self):

        key, value = self.user_input , self.passw_input
         
        # Checks to see if username and password exists 
        if key in data and value == data[key]:

            # Welcomes the user back
            welcome = Label(self.root, text= f"WELCOME BACK \n{self.user_input.upper()}", padx= 200, pady= 50)
            welcome.place(relx= 0.2, rely= 0.5, anchor= "nw")

        # Checks to see if the user put in the wrong username or password 
        elif key not in data or value != data[key]:

            wrong= Label(self.root, text="Wrong Username or Password", padx =200)
            wrong.place(relx= 0.1, rely= 0.5,anchor= "nw")

            # Creates a input field for the user to see if he/she is a new user or not 
            question = Entry(self.root, width= 20)
            question.place(relx= 0.25, rely=0.6, anchor="nw")

            question_text = Label(self.root, text= "Are You A New User? Yes / No : ")
            question_text.place(relx= 0.01, rely= 0.6, anchor= "nw")

            # Make a button for the user to press when finished with answering the question above 
            enter_answ = Button(self.root, text= "ENTER", width= 30, command= lambda : self.answer_check(answer=question.get()))
            enter_answ.place(relx= 0.6, rely= 0.6)
            self.root.mainloop()

    def answer_check(self, answer):

        # If the user types the answer yes. It destroys this window and makes a new one create a new user
        if answer == "yes":
            New_user(root=self.root)

        # If user answers with no , then it starts again and asks user to login 
        if answer == "no" :
            Visual(old_root=self.root)

class New_user:
    def __init__(self, root):
        
        # Destroyes the old window and creates a new one after it 
        root.destroy()
        self.data = data

        # Creates a new window to create a new user 
        self.new_root = Tk()
        self.win_size = self.new_root.geometry("800x500")
        self.color = self.new_root.configure(bg="black")
        self.font = font.Font(size=30)

        self.home_screen()

    def home_screen(self):
        title = Label(self.new_root, text="CREATE NEW USER LOGIN ", padx=200, anchor="center", bg="grey")
        title.place(relx=0.5, rely=0.0, anchor="n")

        self.regestration()

    def regestration(self):

        # The input fields for the new login information for the new user account 
        user_text = Label(self.new_root, text="USERNAME :", bg="grey")
        username = Entry(self.new_root, width=50)

        passw_text = Label(self.new_root, text="PASSWORD :", bg="grey")
        password = Entry(self.new_root, width=50)

        user_text.place(rely=0.1, anchor="nw")
        username.place(relx=0.1, rely=0.1, anchor="nw")

        passw_text.place(rely=0.2, anchor="nw")
        password.place(relx=0.1, rely=0.2, anchor="nw")

        # Create a button to verify if the user information already exists
        submit = Button(self.new_root, text="CREATE USER", padx=80, pady=10, command=lambda :self.save_new_user(username= username,
                                                                                                            password= password))
        submit.place(relx=0.6, rely=0.2, anchor="sw")

   
    def save_new_user(self, username, password):

        # if user information already exists , it waits 2seconds then destroys the current window and makes a new window for the user to create a new account 
        if username.get() in data:
            in_use = Label(self.new_root, text= "USERNAME ALEARDY EXISTS", padx= 200)
            in_use.place(relx= 0.0, rely= 0.7, anchor= "sw")

            time.sleep(2)

            New_user(root=self.new_root)

        # If the user information doesn't exists yet , it puts it into the a dictionary called "data"
        data[username.get()] = password.get()

         # Assigns a button to verify your succesfull login and also destroying the button at the sametime and creating a diffrent one .
        login_retry = Button(self.new_root ,text="LOGIN", width= 80, command=lambda :self.succes(button=login_retry))
        login_retry.place(relx= 0.15, rely= 0.8)


    def succes(self,button):
      
        # Destroy the old button 
        button.destroy()

        # Tells the user that he/she succesfully logged in .
        succes_login = Label(self.new_root, text="YOU HAVE SUCCESFULLY CREATED A NEW USER , CLICK BELOW TO LOGIN IN ",
                   padx=200)
        succes_login.place(relx=0.0, rely=0.5, anchor="sw")
        
        # Creates a button to verify your new user account 
        Button(self.new_root, text="Click HERE TO LOGIN", width= 100, command=lambda :self.retry_login()).place(relx= 0.05, rely= 0.6)

        self.new_root.mainloop()

    def retry_login(self):

        # Goes to the beginning of the program where you test your account login 
        Visual(old_root=self.new_root)


root = Tk()
main = Visual(root)

Answer 1

Some usual PEP8 comments:

username_clear.delete(0,END) -> username_clear.delete(0, END)

in_use.place(relx= 0.0, rely= 0.7, anchor= "sw") -> in_use.place(relx=0.0, rely=0.7, anchor="sw")

New_user should have either been NewUser for a class name or new_user in other cases

Choose meaningful names & avoid typos

Avoid typos like: regestration and Visual could have been MainWindow

New user registration

Sign up option appears only after wrong login submitted, it should have been on the first display of the screen

Check inconsistencies

You ask for Yes/No but check for:

if answer == "yes":
    New_user(root=self.root)

# If user answers with no , then it starts again and asks user to login 
if answer == "no" :
    Visual(old_root=self.root)

Using .lower or .casefold makes a better comparison

if answer.lower() == "yes":

same for no

The Login class could have been methods

The Login class could have been more methods in Visual. I understand that you grouped functionalities under topics like Login and New_user but you don't use constructor as a replacement for a method:

    def __init__(self, username_clear , password_clear , root, user_input, passw_input):
        # clears the input fields
        username_clear.delete(0,END)
        password_clear.delete(0,END)

        self.root = root

        self.user_input = user_input
        self.passw_input = passw_input

        self.login_check()

MVC

You could also group all views under one class and all logic under one class. Views take the logic as parameter and calls the relevant methods as needed. This makes it among others easier to find and test.

Answer 2

I agree with Abdur keep it simple with one class. Other things that could be improved is:

1. Add a data base, you could use pickle or shelve to store user names and passwords.basic start to shelves

2)Add a button for new users right away. 3)your use of relx and rely has some overlapping side effects you might be better off using x and y with real coordinates. 4) Your password entries you can hide the word with show:

password= Entry(self.root,show='*',width=60)

5)To add arguments to a button command you can use partial from functools

from functools import partial

the button side:

submit= Button(self.root,text='Enter',command=partial(your_function,args,arg,arg)

6. lastly I created a new user and when I logged in I purposely typed in a different password, it threw an error. You need some way of checking and telling the user that things don't match up. Simple dialog or messagebox would work. best of luck, Joe