I have a problem.

[Jeymen]

main.py

import tkinter
import pyglet
import os
import customtkinter
from PIL import Image, ImageTk
import qrcode
import sys
import webbrowser
from ui.frames import *
from logic.qrgen import *

class App(customtkinter.CTk):
    def __init__(self):
        super().__init__()
        self.app = customtkinter.CTk()
        self.app.configure(bg='#11121E')
        self.app.geometry('700x500')
        self.app.title('QR code generator')
        Frames.add_frames(self)
        GenerateLogic.qr_gen(self)
        
if __name__ == "__main__":
    app = App()
    app.mainloop()

generate.py

import customtkinter
from logic.qrgen import *
class Generate(customtkinter.CTk):
    def __init__(self):
        self.app = customtkinter.CTk()
        self.app.configure(bg='#11121E')
        self.app.geometry('700x500')
        self.app.title('QR code generator')
    def add_elements(self):
        self.qr_data_entry = customtkinter.CTkEntry(master=self,
         placeholder_text='Enter text', width=237, height=30)
        self.qr_data_entry.place(x=163, y=55)
        self.qr_name_entry = customtkinter.CTkEntry(master=self,
         placeholder_text='Enter file name', width=237, height=30)
        self.qr_name_entry.place(x=163, y=101)
        self.qr_extension_entry = customtkinter.CTkEntry(master=self,
         placeholder_text='Enter file extension', width=237, height=30)
        self.qr_extension_entry.place(x=163, y=147)
        self.button = customtkinter.CTkButton(
     master=self,
     text='Submit',
     command=GenerateLogic.qr_gen(self),
     text_font=('Poppins', 10, 'bold'),
     text_color='White',
     fg_color='343638',
     )
        self.qr_data_entry = customtkinter.CTkEntry(master=self,
         placeholder_text='Enter text', width=237, height=30)
        self.qr_data = self.qr_data_entry.get()
        self.qr_name = self.qr_name_entry.get()
        self.qr_extension = self.qr_extension_entry.get()

qr_gen.py

import customtkinter
import qrcode
from ui.generate import *
class GenerateLogic(customtkinter.CTk):
    def __init__(self):
        self.app = customtkinter.CTk()
        self.app.configure(bg='#11121E')
        self.app.geometry('700x500')
        self.app.title('QR code generator')
    def qr_gen(self):
        self.qr_data = self.qr_data_entry.get()
        self.qr_name = self.qr_name_entry.get()
        self.qr_extension = self.qr_extension_entry.get()

        self.allowed_extensions = [
         'png',
         'jpg',
         'PNG',
         'JPG',
         'jpeg',
         'JPEG',
         'jfif',
         'JFIF',
         'webp',
         'WEBP',
         ]
        if self.qr_extension in self.allowed_extensions:
         try:
             img = qrcode.make(self.qr_data)
             type(img)
             img.save(str(self.qr_name) + '.' + str(self.qr_extension))
             self.error.place_forget()
         except:

              print("QR Code succesfully generated!")

              print("Error!")

              self.error.place(x=405, y=110)
        else:

            print('Please select a valid/supported file extension.')

            self.error.place(x=405, y=110)

Error:

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

[Soif2Sang]

Because self(GenerateLogic class) doesnt have "qr_extension_entry" attribute, you are trying to call an attribute from Generate class