python - Passing string of entry to another function with tkinter -

i'm using python3, trying pass user has typed in username , password box login function when press login button. , login functions should pack label of username onto gui.

code:

import tkinter tkinter import * import sys  def login_gui():     global login_window     global studentid_entry_login     usr_login = stringvar()     pwd_login = stringvar()     login_window=tkinter.tk()     login_window.title("login")     login_window.geometry("200x200+500+300")     username_label_login = tkinter.label(login_window, text="username:").pack()     username_entry_login = tkinter.entry(login_window, textvariable=usr_login).pack()     password_label_login = tkinter.label(login_window, text="\npassword:").pack()     password_entry_login = tkinter.entry(login_window, textvariable=pwd_login).pack()     button_login = tkinter.button(login_window, text="login", command = login).pack()     login_window.mainloop()  def login():     username = usr_login.get()     label1 = tkinter.label(login_window, text=username).pack()     return  login_gui() 

traceback:

traceback (most recent call last):   file "c:/python33/folder/tkinter-test.py", line 25, in <module>     login_gui()   file "c:/python33/folder/tkinter-test.py", line 8, in login_gui     usr_login = stringvar()   file "c:\python33\lib\tkinter\__init__.py", line 254, in __init__     variable.__init__(self, master, value, name)   file "c:\python33\lib\tkinter\__init__.py", line 182, in __init__     self._tk = master.tk attributeerror: 'nonetype' object has no attribute 'tk' 

you can't create stringvar unless tk object has been initialized.

move login_window line appears before other assignments:

login_window=tkinter.tk() usr_login = stringvar() pwd_login = stringvar() 

also, usr_login won't visible in login, you'll nameerror. make global, or consider putting both login_gui , login in class, can access common attributes through self.