Why do I have this error?

Question

1.00/5 (1 vote)

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Python

from kivy.app import App
from kivy.uix.widget import Widget
import random

class PasswordGenerator(Widget):
    pass


class PasswordGenerator(App):
    def build(self):
        return PasswordGenerator()


if __name__ == '__main__':
    PasswordGenerator().run()

print ('Podaj liczbę znaków, które chcesz mieć w haśle: ')
   
password_length = int(input())
    
print('Twoje hasło: ')

chars = 'abcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*'

password = ''
for x in range(password_length):
    password += random.choice(chars)

print(password)

class PasswordGenerator(Widget):
    pass


class PasswordGenerator(App):
    def build(self):
        return PasswordGenerator()


if __name__ == '__main__':
    PasswordGenerator().run()

What I have tried:

I keep getting an error in

Python

if __name__ == '__main__':
    PasswordGenerator().run()

The error says:

Exception: Invalid instance in App.root

What is wrong?

Posted 27-Jul-23 8:54am

Tomasz Góral

Updated 28-Jul-23 2:20am

Andre Oosthuizen

v2

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Andre Oosthuizen · Accepted Answer · 2023-07-28T02:20:00

You are defining two classes with the same name, 'PasswordGenerator' and the second class definition is overwriting the first one. Combine the two class definitions into one and remove the duplicate class -

Python

from kivy.app import App
from kivy.uix.widget import Widget
import random

class PasswordGenerator(Widget):
    def generate_password(self, password_length):
        chars = 'abcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*'
        password = ''
        for x in range(password_length):
            password += random.choice(chars)
        return password

class PasswordGeneratorApp(App):
    def build(self):
        return PasswordGenerator()

if __name__ == '__main__':
    print('Podaj liczbę znaków, które chcesz mieć w haśle: ')
    password_length = int(input())
    print('Twoje hasło: ')
    generator_app = PasswordGeneratorApp()
    password = generator_app.root.generate_password(password_length)
    print(password)
    generator_app.run()

I renamed the one class that extends 'App' to 'PasswordGeneratorApp' to avoid the name conflict, should run now without the error.