Hey there! Let's fix that annoying issue where your main window pops up even when you close the login window without logging in. Here's what's going wrong and how to fix it:

What's the Problem? #

Your current code runs the main window creation logic unconditionally in the global scope, right after the login window's mainloop() finishes. This means no matter how you close the login window (either by logging in successfully or clicking the close button), the main window will always pop up. Also, the MyWindow class structure isn't following Tkinter best practices, which makes controlling the program flow harder.

The Fixed Code #

Here's the revised version that stops the entire script when the login window is closed without logging in:

import sys
from tkinter import *
import paramiko
import time
from tkinter.ttk import Combobox
import tkinter as tk
from tkinter import ttk

LARGE_FONT = ("Verdana", 12)
NORM_FONT = ("Helvetica", 10)
SMALL_FONT = ("Helvetica", 8)

# Global variables for login credentials
username1 = ""
password1 = ""

def popupmsg(msg):
    popup = tk.Tk()
    popup.wm_title("Error")
    label = ttk.Label(popup, text=msg, font=NORM_FONT)
    label.pack(side="top", fill="x", pady=10)
    B1 = ttk.Button(popup, text="Try Again", command=popup.destroy)
    B1.pack()
    popup.mainloop()

class LoginWindow():
    def __init__(self):
        self.root = tk.Tk()
        self.login_success = False  # Flag to track login status
        
        # Set window icon
        image = r"D:\Python\My Projects\Nokia1.png"
        icon = PhotoImage(file=image)
        self.root.call('wm', 'iconphoto', self.root._w, icon)
        
        # Create canvas and widgets
        self.canvas1 = tk.Canvas(self.root, width=400, height=300)
        self.canvas1.pack()
        
        image_bg = tk.PhotoImage(file=r"D:\Python\My Projects\Nokia.png")
        self.canvas1.create_image(50, 10, image=image_bg, anchor=tk.NW)
        
        # Username field
        self.webui_username = tk.Label(self.root, text="Enter Username")
        self.canvas1.create_window(125, 150, window=self.webui_username)
        self.webui_username_Entry = tk.Entry(self.root)
        self.canvas1.create_window(250, 150, window=self.webui_username_Entry)
        
        # Password field
        self.webui_password = tk.Label(self.root, text="Enter Password")
        self.canvas1.create_window(125, 200, window=self.webui_password)
        self.webui_password_Entry = tk.Entry(self.root, show="*")
        self.canvas1.create_window(250, 200, window=self.webui_password_Entry)
        
        # Login button
        self.button1 = tk.Button(text='Login', command=self.done, bg='black', fg='white', font=('helvetica', 9, 'bold'))
        self.canvas1.create_window(200, 250, window=self.button1)
        
        # Bind close event to custom handler
        self.root.protocol("WM_DELETE_WINDOW", self.on_closing)
        
        self.root.title('Nokia Login')
        self.root.mainloop()
    
    def done(self):
        """Handle login button click"""
        global username1, password1
        if self.webui_username_Entry.get() == "alcatel" and self.webui_password_Entry.get() == "Nokia@2016":
            self.login_success = True
            username1 = self.webui_username_Entry.get()
            password1 = self.webui_password_Entry.get()
            self.root.destroy()  # Close login window
        else:
            popupmsg("Wrong Username or password")
    
    def on_closing(self):
        """Handle when login window is closed via close button"""
        self.root.destroy()
        sys.exit()  # Terminate entire script

class MainWindow():
    def __init__(self, win):
        self.new_username = Label(win, text='New Username')
        self.new_password = Label(win, text='New Password')
        self.profile = Label(win, text='Profile Domain')
        self.result = Label(win, text='Result')
        
        global webui_username, webui_Password, outbox, cb
        webui_username = self.t1 = Entry(bd=3)
        webui_Password = self.t2 = Entry()
        outbox = self.outbox_E = Entry()
        
        self.new_username.place(x=100, y=50)
        self.t1.place(x=200, y=50)
        self.new_password.place(x=100, y=100)
        self.t2.place(x=200, y=100)
        self.profile.place(x=100, y=150)
        
        self.b2 = Button(win, text='Create', command=self.auth)
        self.b2.place(x=200, y=200)
        
        self.result.place(x=100, y=240)
        self.outbox_E.place(x=200, y=240, width=200, height=40)
        
        # Dropdown list
        self.data = ("Voda", "unknown", 'All Network')
        cb = Combobox(win, values=self.data)
        cb.place(x=200, y=150)
    
    def auth(self):
        """Authentication logic for SSH connection"""
        global ipa, ssh
        ipa = "xx.xx.xx.xx"
        try:
            ssh = paramiko.SSHClient()
            ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
            ssh.connect(ipa, 22, 'root', 'Nokia@2016')
            shell = ssh.invoke_shell()
            print("Auth Success")
        except paramiko.AuthenticationException:
            print("\nWrong username or Password, Please try again\n")
        except TimeoutError:
            print("\nIP is not reachable. please check connection\n")
        
        # Handle profile selection
        profile_unknown = " unknown"
        profile_Voda = " Voda"
        profile_All = ' "Voda","unknown"'
        
        if cb.get() == "unknown":
            profile_d = profile_unknown
        elif cb.get() == "Voda":
            profile_d = profile_Voda
        elif cb.get() == 'All Network':
            profile_d = profile_All

# Main program flow
if __name__ == "__main__":
    # Start login window
    login_app = LoginWindow()
    
    # Only start main window if login was successful
    if login_app.login_success:
        window = Tk()
        image = r"D:\Python\My Projects\Nokia2.png"
        icon = PhotoImage(file=image)
        window.call('wm', 'iconphoto', window._w, icon)
        window.title('Vendor tool')
        window.geometry("500x400+10+10")
        
        mywin = MainWindow(window)
        window.mainloop()

Key Changes Explained #

1. Refactored Login Window: Created a dedicated LoginWindow class with a proper __init__ method, and added a login_success flag to track if the user logged in successfully.
2. Close Event Handling: Used self.root.protocol("WM_DELETE_WINDOW", self.on_closing) to bind the window close event to a handler that calls sys.exit(), terminating the entire script when the login window is closed without logging in.
3. Conditional Main Window Launch: The main window is only created and launched if the login_success flag is True, which only happens when the user enters correct credentials and clicks the login button.
4. Cleaner Class Structure: Separated login and main window logic into distinct classes for better readability and maintainability.

内容的提问来源于stack exchange，提问作者NewCoderBiggnerInThisLife