CODEWITHSUNDEEP
python-3.xtkinter
MediocreBeverage
MediocreBeverage

Reputation: 1

name 'main_window' is not defined

from tkinter import *

def create_main_window():
    global main_window
    main_window = Toplevel()
    main_window.update()

entrance_window = Tk()
first_text_label = Label(entrance_window, text="you are in:").grid(row=0, column=0)
place_entry = Entry(entrance_window).grid(row=0, column=1)

submit_button = Button(entrance_window, text="Submit", command=create_main_window).grid(row=1, column=0, columnspan=2)
Label(main_window, text=f"{place_entry}").pack()
entrance_window.mainloop()

the program should open a new window with the text from the entry box from the first window but it either shows None if I write

Label(main_window, text=f"{place_entry}").pack()

in the create_main_window or it gives me an error saying that main_window is not defined if I write it after the button code.

Can someone help with this?

Upvotes: 0

Views: 263

Answers (3)

toyota Supra
toyota Supra

Reputation: 4537

Never used global. Don't use the wildcard from tkinter import *

The Label widget must be placed inside the create_main_window() function when you want to see the widget.

snippet:

import tkinter as tk


def create_main_window() -> None :   
    main_window = tk.Toplevel()
    tk.Label(main_window, text=f"{place_entry.get()}").pack()
     

entrance_window = tk.Tk()

first_text_label = tk.Label(entrance_window, text="you are in:").grid(row=0, column=0)

place_entry = tk.Entry(entrance_window)
place_entry.grid(row=0, column=1)

tk.Button(entrance_window, text="Submit", command=create_main_window).grid(row=1, column=0, columnspan=2)
 
entrance_window.mainloop()

if __name__=='__main__':
    create_main_window()

Screenshot:

enter image description here

Upvotes: 0

TheLizzard
TheLizzard

Reputation: 7680

Try this:

from tkinter import *


def create_main_window():
    global main_window
    main_window = Toplevel(main_window)
    label = Label(main_window, text=f"{place_entry.get()}")
    label.pack()
    # main_window.update() # This is useless


entrance_window = Tk()

first_text_label = Label(entrance_window, text="You are in:")
first_text_label.grid(row=0, column=0)

place_entry = Entry(entrance_window)
place_entry.grid(row=0, column=1)

submit_button = Button(entrance_window, text="Submit", command=create_main_window)
submit_button.grid(row=1, column=0, columnspan=2)
entrance_window.mainloop()

I moved the label creation inside create_main_window. Also please note that using var = a().b(), saves what ever b() returns inside var. That is why when you use var = Entry(...).pack(...), var is always None.

Upvotes: 1

Cmd858
Cmd858

Reputation: 866

This is because you are trying to add a Label to an object that doesn't exist. Move the Label function to the create_main_window() function, like below:

from tkinter import *

def create_main_window():
    global main_window, entrance_window
    main_window = Toplevel()
    place_entry = Entry(entrance_window).grid(row=0, column=1)
    Label(main_window, text=f"{place_entry}").pack()
    main_window.update()

entrance_window = Tk()
first_text_label = Label(entrance_window, text="you are in:").grid(row=0, column=0)

submit_button = Button(entrance_window, text="Submit", command=create_main_window).grid(row=1, column=0, columnspan=2)
entrance_window.mainloop()

Upvotes: 0

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