KivyMD issue with Menu (MDDropdownMenu) operation on multiple screens

[Honey Budger]

When working with a single screen, everything works fine. But when I try to add MDDropdownMenu to any other screen (when I add ScreenManager and the second screen), it gives:

AttributeError: 'super' object has no attribute '__getattr__'

Please help me to understand and resolve this issue. Here is the code itself:

from kivy.lang import Builder
from kivymd.app import MDApp
from kivymd.uix.menu import MDDropdownMenu
from kivy.uix.screenmanager import ScreenManager, Screen

kv = '''
ScreenManager:
    FirstScreen:
    SecondScreen:

<FirstScreen>
    name: 'first'
    MDRaisedButton:
        id: button
        text: "PRESS ME"
        pos_hint: {"center_x": .5, "center_y": .5}
        on_release: root.menu.open()
        
<SecondScreen>
    name: 'second'
'''
class FirstScreen(Screen):
    def btn_show(self):
        menu_items = [{"text": f"Item {i}"} for i in range(5)]
        self.menu = MDDropdownMenu(
            caller=self.ids.button, items=menu_items, width_mult=4
        )
        self.menu.bind(on_release=self.menu_callback)

    def menu_callback(self, instance_menu, instance_menu_item):
        print(instance_menu, instance_menu_item)

class SecondScreen(Screen):
    pass

class Test(MDApp):
    def build(self):
        screen = Builder.load_string(kv)
        return screen

sm = ScreenManager()
sm.add_widget(FirstScreen(name='first'))
sm.add_widget(SecondScreen(name='second'))

Test().run()

[ElliotG]

The Method btn_show() is never executed so self.menu is not created.  When the button is pressed root.menu does not exist, so you get an attribute error.

Changning btn_show to on_kv_post, runs the code when the screen is instanced, then the rest of the code works.  You have some redundant code creating screens, I commented that out.

from kivy.lang import Builder

from kivymd.app import MDApp

from kivymd.uix.menu import MDDropdownMenu

from kivy.uix.screenmanager import ScreenManager, Screen

kv = '''

ScreenManager:

    FirstScreen:

    SecondScreen:

<FirstScreen>

    name: 'first'

    MDRaisedButton:

        id: button

        text: "PRESS ME"

        pos_hint: {"center_x": .5, "center_y": .5}

        on_release: root.menu.open()

<SecondScreen>

    name: 'second'

'''

class FirstScreen(Screen):

    def on_kv_post(self, base_widget):  

        menu_items = [{"text": f"Item {i}"} for i in range(5)]

        self.menu = MDDropdownMenu(

            caller=self.ids.button, items=menu_items, width_mult=4

        )

        self.menu.bind(on_release=self.menu_callback)

    def menu_callback(self, instance_menu, instance_menu_item):

        print(instance_menu, instance_menu_item)

class SecondScreen(Screen):

    pass

class Test(MDApp):

    def build(self):

        screen = Builder.load_string(kv)

        return screen

# sm = ScreenManager()

# sm.add_widget(FirstScreen(name='first'))

# sm.add_widget(SecondScreen(name='second'))

Test().run()