Kivy Python: buttons and classes for multiple screens

Question

I have a problem with my Kivy Python Code. I have 2 screens: 1st is to navigate to the second screen and on the 2nd screen there is a button to add text to a scrollview...navigating is working but it does not add any text to the scrollview...I think I need some help here! AttributeError: 'super' object has no attribute ' getattr '

import kivy
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.gridlayout import GridLayout
from kivy.uix.textinput import TextInput
from kivy.uix.button import Button
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.clock import Clock, mainthread
from kivy.core.window import Window
from kivy.uix.scrollview import ScrollView
from kivy.effects.scroll import ScrollEffect
from kivy.lang import Builder


Builder.load_string("""

<MenuScreen>:
    name: 'mainmenu'
    BoxLayout:
        spacing: 1
        orientation: "vertical"

        Label:
            text: "MAIN MENU"
        Button:
            text: 'Go to Screen 2'
            on_release: 
                root.manager.current = 'screen2'
                root.manager.transition.direction = "left"
        Button:
            text: 'Quit'
            on_release: root.manager.current = app.exit_software()
        

<Screen2>:
    name: 'screen2'
    BoxLayout:
        spacing: 1
        orientation: "vertical"

        ScrollView:
            id: scroll_view
            always_overscroll: False
            BoxLayout:
                size_hint_y: None
                height: self.minimum_height
                orientation: 'vertical'
                Label:
                    id: label
                    text: "You can add some Text here by pressing the button"
                    size_hint: None, None
                    size: self.texture_size 
        Button:
            text: 'Add text!'
            size_hint_y: 0.1
            on_release: app.add_text()
            

        Button:
            text: 'Back to main menu'
            size_hint_y: 0.1
            on_release: 
                root.manager.current = 'mainmenu'
                root.manager.transition.direction = "right"
            
""")

# Declare both screens
class MenuScreen(Screen):
   pass

class Screen2(Screen):
    pass

class AddTextApp(App):
    def __init__(self,**kwargs):
        super().__init__(**kwargs)

    def build(self):
        # Create the screen manager
        sm = ScreenManager()
        sm.add_widget(MenuScreen(name='mainmenu'))
        sm.add_widget(Screen2(name='screen2'))

        return sm

    def add_text(self):
        self.root.ids.label.text += f"Some new Text\n"
        self.root.ids.scroll_view.scroll_y = 0

    def exit_software(self):
       App.get_running_app().stop()


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

Thank you very much in advance!

Answer 1

The error occurred because self.root.ids gets access to widgets located in the root widget of the main class. To access the secondary screen elements, you need to add it to the main class (in your case, in ScreenManager ) and set its id . Also, you have a lot of imported excess, so that it is clearly visible, I advise you to use Pycharm or something like that.

from kivy.app import App
from kivy.uix.screenmanager import Screen
from kivy.lang import Builder

kv = """
<MenuScreen>:
    name: 'mainmenu'
    BoxLayout:
        spacing: 1
        orientation: "vertical"

        Label:
            text: "MAIN MENU"
        Button:
            text: 'Go to Screen 2'
            on_release: 
                root.manager.current = 'screen2'
                root.manager.transition.direction = "left"
        Button:
            text: 'Quit'
            on_release: root.manager.current = app.exit_software()


<Screen2>:
    name: 'screen2'
    BoxLayout:
        spacing: 1
        orientation: "vertical"

        ScrollView:
            id: scroll_view
            always_overscroll: False
            BoxLayout:
                size_hint_y: None
                height: self.minimum_height
                orientation: 'vertical'
                Label:
                    id: label
                    text: "You can add some Text here by pressing the button"
                    size_hint: None, None
                    size: self.texture_size 
        Button:
            text: 'Add text!'
            size_hint_y: 0.1
            on_release: app.add_text()


        Button:
            text: 'Back to main menu'
            size_hint_y: 0.1
            on_release: 
                root.manager.current = 'mainmenu'
                root.manager.transition.direction = "right"
                

ScreenManager:
    MenuScreen:
        id: menu_scr
        
    Screen2:
        id: scr_2
        
"""


class MenuScreen(Screen):
    pass


class Screen2(Screen):
    pass


class AddTextApp(App):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)

    def build(self):
        return Builder.load_string(kv)

    def add_text(self):
        self.root.ids.scr_2.ids.label.text += f"Some new Text\n"
        self.root.ids.scr_2.ids.scroll_view.scroll_y = 0

    @staticmethod
    def exit_software():
        App.get_running_app().stop()


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