AttributeError: '_tkinter.tkapp' object has no attribute 'username'

[Konstantin23]

I was following up with multiple tutorials online for designing a tkinter gui app for a password manager program I made recently, and so I split up the app into a package of multiple python scripts, with the __innit__.py file of the package containg the parent root class and then multiple other scripts containing tk.frame classes, all inheriting from the parent class.

from .home import *
from .register import *
from .login import *
from .menu import *
from .store import *
from .retrieve import *
from PIL import Image, ImageTk
import tkinter as tk


class App(tk.Tk):
    
    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        
        self.configure(bg="black")
        self.geometry("500x500+500+100")
        self.minsize(500, 500)
        self.maxsize(500, 500)
        self.title("The Vault v1.0")
        
        self.home = ImageTk.PhotoImage(
            Image.open('./interface/Home.png').resize((35, 30), Image.ANTIALIAS))
        
        container = tk.Frame(self)
        container.pack(side="top", fill="both", expand=True)
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)
        #container.configure(bg="black", highlightbackground="white", highlightthickness=2)
        
        self.frames = {}
        for F in (home, register, login, menu, store, retrieve):
            page_name = F.__name__
            frame = F(parent=container, controller=self)
            self.frames[page_name] = frame
            frame.grid(row=0, column=0, sticky="nsew")

        self.show_frame("home")  
        self.bind('<Escape>', lambda x: self.destroy())
        global username
    
    def exit(self):
        self.destroy()
        
    def show_frame(self, page_name):
        frame = self.frames[page_name]
        frame.tkraise()
        frame.focus_set()
        self.unbinder()
        frame.binds()

    def unbinder(self):
        self.unbind('<Return>')
        self.unbind('1')
        self.unbind('2')
        self.unbind('3')
        self.unbind('4')
        self.unbind('5')
        
    def exitButton(self, frame):
        note = tk.Label(self, bg= "black", fg="white", text="(esc)", font=("Terminal", 10))
        exitBut = tk.Button(frame, bg= "black", fg="white",
                            text='EXIT', font=("Terminal", 20),
                            command=exit,
                            activebackground="black",
                            relief=tk.SOLID,
                            borderwidth=0,
                            padx=0, pady=0,
                            cursor="hand2")
        exitBut.place(relx=0.9, rely=0.9, y=-10,anchor=tk.CENTER)
        note.place(relx=0.9, rely=0.9, x=-8, y=10, anchor=tk.CENTER)
        
    def homeButton(self, frame):
        def home_clear(self):
            self.show_frame('home')
            self.username = ""
        buttn = tk.Button(frame, image=self.home,
                        bg="black", command=lambda: home_clear(self),
                        activebackground="black",
                        relief=tk.SOLID,
                        borderwidth=0,
                        padx=0, pady=0, cursor="hand2")
        buttn.place(relx=0.05, rely=0.05)
        
def start():
    app = App()
    app.mainloop()

In the above __innit__.py file, there is a global variable username which needs to be passed on to and modified by other classes so that they may call various backend function using 'username' as a parameter.
Now the problem persists in the code below where it is calling the username variable in the class' innit function:

import tkinter as tk
from customtkinter import CTkComboBox, CTkTextbox
from .backend import *


class retrieve(tk.Frame):
    def __init__(self, parent, controller):
        self.controller = controller
        tk.Frame.__init__(self, parent, bg="black", highlightthickness=5, highlightcolor='white')
        self.controller = controller
        head = tk.Label(self, bg="black", fg="white", text="STORED DATA",
                        font=("Terminal", 32))    
        # retrieve _passwords: returns a list of tuples split in two lists with same number of elements.
        services, data = retrieve_passwords(self.controller.username) # THIS THROWS ERROR
        service_list.configure(values=services)
        
        def combobox_callback(choice):
            data_out = data[services.index(choice)]
            data_disp.insert("0.0", data_out)
            print("combobox dropdown clicked:", choice)    
        service_list = CTkComboBox(self, fg_color="black", text_color="white", font=("Terminal", 20, "bold"), justify="left",
                              corner_radius=0, width=450, height=36, border_width=0, border_color="white", 
                              command=combobox_callback, dropdown_fg_color="black", dropdown_text_color="white", 
                              dropdown_font=("Terminal", 20, "bold"),hover=False, button_color="black", 
                              button_hover_color="white", dropdown_hover_color="black")
        
        service_list.set(">SERVICE NAME")
        data_disp = CTkTextbox(self, fg_color="black", text_color="white", font=("Terminal", 22, "bold"),
                          scrollbar_button_color="white", scrollbar_button_hover_color="white",wrap=tk.WORD,
                            corner_radius=0, width=450, height=250, border_width=0)
        
        data_disp.configure(state=tk.DISABLED)
        back = tk.Button(self,
                          bg="black", fg="white",
                          text='BACK', font=("Terminal", 18, "bold"),
                          command=lambda: controller.show_frame("menu"),
                          activebackground="black",
                          relief=tk.SOLID,
                          borderwidth=0,
                          padx=16, pady=0, cursor="hand2")
        entNote = tk.Label(self,bg="black", fg="white", text="(enter)",
                           font=("Terminal", 10))

        head.place(relx=0.5, rely=0.1, anchor=tk.CENTER)
        service_list.place(relx=0.1, rely=0.3, y=-10,x=-35,anchor=tk.W)
        data_disp.place(relx=0.1, rely=0.45, x=-30, y=65,anchor=tk.W)
        back.place(relx=0.5, rely=0.9, anchor=tk.CENTER)
        entNote.place(relx=0.5, rely=0.9, y=20, anchor=tk.CENTER)
        controller.exitButton(self)
        controller.homeButton(self) 
        
    def binds(self):
        self.focus_set()
        self.controller.bind('<Return>', lambda x: self.controller.show_frame("menu"))

It throws this error everytime I try run the application:

Error:
Traceback (most recent call last):
  File "a:/python projects/password generator/main.py", line 3, in <module>
    interface.start()
  File "a:\python projects\password generator\interface\__init__.py", line 86, in start
    app = App()
  File "a:\python projects\password generator\interface\__init__.py", line 34, in __init__
    frame = F(parent=container, controller=self)
  File "a:\python projects\password generator\interface\retrieve.py", line 14, in __init__
    services, data = retrieve_passwords(self.controller.username)
  File "C:\Users\konstantin\AppData\Local\Programs\Python\Python38\lib\tkinter\__init__.py", line 2345, in __getattr__
    return getattr(self.tk, attr)
AttributeError: '_tkinter.tkapp' object has no attribute 'username'

PS: I am fairly new to python classes and tkinter so I might have made some mistakes with the inheritances, just cant figure which ones exactly so any help at all is very much appreciated, thanks