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

Question

Python

The code:

from kivy.lang import Builder
from kivy.uix.floatlayout import FloatLayout
from kivymd.uix.tab import MDTabsBase
from kivymd.app import MDApp
KV = '''
Screen:
    MDTabs:
        id: tabs
<Tab1>:
    BoxLayout:
        MDTextField:
            id: vvod
            pos_hint: {'center_x':.5,'center_y':.5}
        MDRaisedButton:
            pos_hint: {'center_x':.1,'center_y':.4}
            on_press: app.func()
'''
class Tab1(MDTabsBase,FloatLayout):
    pass
class Test(MDApp):
    def build(self):
        return Builder.load_string(KV)
    def on_start(self):
        self.root.ids.tabs.add_widget(Tab1(text='Tab1'))
    def func(self):
        print(self.root.ids.vvod.text)
Test().run()

Error when clicking the button:

Traceback (most recent call last):
   File "kivy\properties.pyx", line 861, in kivy.properties.ObservableDict.__getattr__
 KeyError: 'vvod'
 
 During handling of the above exception, another exception occurred:
 
 Traceback (most recent call last):
   File "C:\Users\lolo\PycharmProjects\FindWord\FindWord.py", line 28, in <module>
     Test().run()
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\app.py", line 950, in run
     runTouchApp()
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\base.py", line 582, in runTouchApp
     EventLoop.mainloop()
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\base.py", line 347, in mainloop
     self.idle()
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\base.py", line 391, in idle
     self.dispatch_input()
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\base.py", line 342, in dispatch_input
     post_dispatch_input(*pop(0))
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\base.py", line 248, in post_dispatch_input
     listener.dispatch('on_motion', etype, me)
   File "kivy\_event.pyx", line 709, in kivy._event.EventDispatcher.dispatch
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\core\window\__init__.py", line 1416, in on_motion
     self.dispatch('on_touch_up', me)
   File "kivy\_event.pyx", line 709, in kivy._event.EventDispatcher.dispatch
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\core\window\__init__.py", line 1452, in on_touch_up
     if w.dispatch('on_touch_up', touch):
   File "kivy\_event.pyx", line 709, in kivy._event.EventDispatcher.dispatch
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\uix\relativelayout.py", line 313, in on_touch_up
     ret = super(RelativeLayout, self).on_touch_up(touch)
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\uix\widget.py", line 567, in on_touch_up
     if child.dispatch('on_touch_up', touch):
   File "kivy\_event.pyx", line 709, in kivy._event.EventDispatcher.dispatch
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\uix\widget.py", line 567, in on_touch_up
     if child.dispatch('on_touch_up', touch):
   File "kivy\_event.pyx", line 709, in kivy._event.EventDispatcher.dispatch
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\uix\widget.py", line 567, in on_touch_up
     if child.dispatch('on_touch_up', touch):
   File "kivy\_event.pyx", line 709, in kivy._event.EventDispatcher.dispatch
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivymd\uix\carousel.py", line 93, in on_touch_up
     return super().on_touch_up(touch)
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\uix\carousel.py", line 610, in on_touch_up
     super(Carousel, self).on_touch_down(touch)
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\uix\widget.py", line 545, in on_touch_down
     if child.dispatch('on_touch_down', touch):
   File "kivy\_event.pyx", line 709, in kivy._event.EventDispatcher.dispatch
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\uix\relativelayout.py", line 297, in on_touch_down
     ret = super(RelativeLayout, self).on_touch_down(touch)
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\uix\widget.py", line 545, in on_touch_down
     if child.dispatch('on_touch_down', touch):
   File "kivy\_event.pyx", line 709, in kivy._event.EventDispatcher.dispatch
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\uix\widget.py", line 545, in on_touch_down
     if child.dispatch('on_touch_down', touch):
   File "kivy\_event.pyx", line 709, in kivy._event.EventDispatcher.dispatch
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\uix\widget.py", line 545, in on_touch_down
     if child.dispatch('on_touch_down', touch):
   File "kivy\_event.pyx", line 709, in kivy._event.EventDispatcher.dispatch
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivymd\uix\behaviors\ripplebehavior.py", line 283, in on_touch_down
     return super().on_touch_down(touch)
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivymd\uix\button.py", line 1004, in on_touch_down
     return super().on_touch_down(touch)
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivymd\uix\button.py", line 939, in on_touch_down
     return super().on_touch_down(touch)
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\uix\behaviors\button.py", line 151, in on_touch_down
     self.dispatch('on_press')
   File "kivy\_event.pyx", line 705, in kivy._event.EventDispatcher.dispatch
   File "kivy\_event.pyx", line 1248, in kivy._event.EventObservers.dispatch
   File "kivy\_event.pyx", line 1132, in kivy._event.EventObservers._dispatch
   File "C:\Users\lolo\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\lang\builder.py", line 57, in custom_callback
     exec(__kvlang__.co_value, idmap)
   File "<string>", line 12, in <module>
   File "C:\Users\lolo\PycharmProjects\FindWord\FindWord.py", line 27, in func
     print(self.root.ids.vvod.text)
   File "kivy\properties.pyx", line 864, in kivy.properties.ObservableDict.__getattr__
 AttributeError: 'super' object has no attribute '__getattr__'

Without the Tabs widget, everything works. Tell me how to fix the error
It seems to me that the error is in the lines self.root.ids, or rather in their collision

Answer 1

from kivy.lang import Builder
from kivymd.app import MDApp

KV = '''
BoxLayout:
    padding: "10dp"

    MDRaisedButton:
        id: button_show_text
        on_press: app.show_text()
    MDTextField:
        id: text_field
        hint_text: "Helper text on error (press 'Enter')"
        helper_text: "There will always be a mistake"
        helper_text_mode: "on_error"
        pos_hint: {"center_y": .5}

'''


class Test(MDApp):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.screen = Builder.load_string(KV)

    def build(self):
        self.screen.ids.text_field.bind(
            on_text_validate=self.set_error_message,
            on_focus=self.set_error_message,
        )
        return self.screen

    def set_error_message(self, instance_text_field):
        self.screen.ids.text_field.error = True
    def show_text(self):
        print(self.screen.ids.text_field.text)

Test().run()