[Kivy] AttributeError: 'NoneType' object has no attribute 'bind'

[Kivy] AttributeError: 'NoneType' object has no attribute 'bind' - Printable Version

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+--- Thread: [Kivy] AttributeError: 'NoneType' object has no attribute 'bind' (/thread-25817.html)

AttributeError: 'NoneType' object has no attribute 'bind' - faszination_92 - Apr-12-2020

Hey guys, I'm pretty new at coding kivy and think one of you could help me with a simple solution. I want to include the variable named [show_text] into my [Label] , [text] at the [main.kv]. right now i get the Message:

BuilderException: Parser: File "C:\Users\Lukas\PycharmProjects\test_app\main.kv", line 57:
...
55: pos_hint: {"top": 1, "left": 2}
56: size_hint: 1, .7
>> 57: text: app.show_text
58: id: aufgaben_player
...
AttributeError: 'NoneType' object has no attribute 'bind'

Thanks for helping me!

main.py

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.button import ButtonBehavior
from kivy.uix.image import Image
from kivy.uix.screenmanager import Screen, ScreenManager
from kivy.properties import StringProperty, ObjectProperty
import random
from karten import *

class WindowManager(ScreenManager):
    home_screen = ObjectProperty(None)
    game_text_screen = ObjectProperty(None)

class ImageButton(ButtonBehavior, Image):
    pass

class HomeScreen(Screen):
    pass

class GameText(Screen):
    pass

kv = Builder.load_file("main.kv")

class MainApp(App):
    show_text = StringProperty()

    def build(self):
        return kv

    def show_game_text_first(self):
        show_text = Karten[random.randint(0, 2)]
        print(show_text)

if __name__ == "__main__":
    MainApp().run()

main.kv

#:import utils kivy.utils

WindowManager:

    HomeScreen:
        name: "home_screen"
        FloatLayout:
            canvas:
                Color:
                    rgb: utils.get_color_from_hex("#3983F2")
                Rectangle:
                    size: self.size
                    pos: self.pos

            Label:
                pos_hint: {"top": 0.7, "left": 1}
                size_hint: 1, .1
                text: "Schere Stein Papier"
                font_size: min(root.height, root.width)/15
                id: title_label

            GridLayout:
                rows: 1
                pos_hint: {"top": .2, "left": 5}
                size_hint: 1, .1

                ImageButton:
                    source: "icons/weiter.png"
                    on_press:
                        self.source = "icons/weiterhell.png"
                    on_release:
                        self.source = "icons/weiter.png"
                        app.root.current = "game_text_screen"
                        app.show_game_text_first()


    GameText:
        name: "game_text_screen"
        FloatLayout:
            canvas:
                Color:
                    rgb: utils.get_color_from_hex("#3983F2")
                Rectangle:
                    size: self.size
                    pos: self.pos

            Label:
                pos_hint: {"top": 1, "left": 1}
                size_hint: 1, .1
                text: "Schere Stein Papier"
                font_size: min(root.height, root.width)/15
                id: title_label

            Label:
                pos_hint: {"top": 1, "left": 2}
                size_hint: 1, .7
                text: app.show_text
                id: aufgaben_player

RE: AttributeError: 'NoneType' object has no attribute 'bind' - faszination_92 - Apr-12-2020

sry still same

RE: AttributeError: 'NoneType' object has no attribute 'bind' - Larz60+ - Apr-12-2020

Please always show complete, unaltered error traceback (in error tags) as it contains important information that can be used to isolate cause of error, and call stack prior to failure.