'NoneType' object is not subscriptable using kv - kivy

Question

I'm trying to make a phone app, and want to be able to navigate between multiple screens.
However I don't know what to do with the syntax error that keeps being returned.
I'm new to kivy, and looked at a ton of tutorial stuff to put my code together, help would be much appreciated.
Here is code on main file
from kivy.uix.screenmanager import ScreenManager, Screen #screen manager is a widget dedicated to managing multiple screens for your application.
from kivy.uix.button import Button #creates the button in kivy
from kivy.uix.floatlayout import FloatLayout #means can place elements based on windows size
from kivy.config import Config
from kivy.properties import ObjectProperty
from kivy.uix.popup import Popup
from kivy.uix.widget import Widget
from kivy.uix.label import Label
Config.set('graphics', 'resizable', True)
kv = Builder.load_file("phoneassistant.kv") #links to kv file where graphics are loaded
sm = WindowManager() #sm will control moving between screens using the ScreenManager class
#creating classes for all screen on app help specify methods for individual screens using argument Screen
class LoginWindow(Screen, FloatLayout):
def mainBtn(self):
self.reset()
sm.current = "main"
def createBtn(self):
self.reset()
sm.current = "create"
class CreateAccountWindow(Screen, FloatLayout):
def loginBtn(self):
self.reset()
sm.current = "login"
class MainWindow(Screen, FloatLayout):
def loginBtn(self):
self.reset()
sm.current = "login"
def settingsBtn(self):
self.reset()
sm.current = "settings"
def storageBtn(self):
self.reset()
sm.current = "storage"
class SettingsWindow(Screen, FloatLayout):
pass
class StorageWindow(Screen, FloatLayout):
pass
class AIWindow(Screen, FloatLayout):
pass
class WindowManager(ScreenManager): #this won't be a sceen, ScreenManager is to manage transitions between all screens
pass
#gives the screens names
screens = [LoginWindow(name = "login"), CreateAccountWindow(name = "create"), MainWindow(name="main"),
SettingsWindow(name = "settings"),StorageWindow(name = "storage"), AIWindow(name = "AI")]
#adds the screens to the manager
for screen in screens:
sm.add_widget(screen)
#sends user to login page whenever program is ran
sm.current = "login"
class PhoneAssistantApp(App): #creates the app class
def build(self):
return sm #returns screens when class is ran
if __name__ == "__main__": #runs the app
PhoneAssistantApp().run()
The code on the kv file
<ScreenManagement>:
transition: SlideTransition
LoginWindow:
CreateAccountWindow:
MainWindow:
SettingsWindow:
StorageWindow:
AIWindow:
<LoginWindow>:
name: "login"
    FloatLayout:
Button:
         text: "Don't have an account?"
font_size: 0.2, 0.1
            background_color: 0, 0, 1, 1
size_hint: 0.4, 0.3
pos: {"x":0.5, "y":0.25}
            on_release:
                root.manager.transition.direction = "left"
                root.manager.transition.duration = 1
root.createBtn()
Button:
            text: "Login here"
font_size: 0.1, 0.2
            background_color: 1, 0, 0, 1
size_hint: 0.4, 0.3
pos_hint: {"x":0.5, "y":0.75}
            on_release:
                root.manager.transition.direction = "right"
                root.manager.transition.duration = 1
                root.mainBtn()
  
<CreateAccountWindow>:
name: "create"
    FloatLayout:
        Button:
            text: "Create login"
font_size: 0.25, 0.25
            background_color : 1, 1, 0, 1
size_hint: 0.5, 0.5
pos_hint: {"x":0.5, "y":0.1}
            on_release:
                app.root.current = "login"
                root.manager.transition.direction = "right"
                root.manager.transition.duration = 1
 
<MainWindow>:
name: "main"
    FloatLayout:
        Button:
            text: "Return to login page"
font_size: 0.25, 0.25
            background_color : 1, 1, 0, 1
size_hint: 0.25, 0.35
pos_hint: {"x":0.5, "y":0.1}
            on_release:
                app.root.current = "login"
                root.manager.transition.direction = "left"
                root.manager.transition.duration = 1
        Button:
            text: "Access Settings"
font_size: 0.5, 0.5
            background_color : 1, 0, 1, 1
size_hint: 0.35, 40.5
pos_hint: {"x":0.1, "y":0.9}
            on_release:
                app.root.current = "settings"
                root.manager.transition.direction = "right"
                root.manager.transition.duration = 1
        Button:
            text: "Access Storage"
font_size: 0.75, 0.75
            background_color : 1, 1, 1, 0
size_hint: 0.45, 0.25
pos_hint: {"x":0.9, "y":0.5}
            on_release:
                app.root.current = "storage"
                root.manager.transition.direction = "right"
                root.manager.transition.duration = 1
 
<SettingsWindow>:
name: "settings"
    FloatLayout:
        Button:
            text: "Return to Main Menu"
            background_color: 0, 1, 1, 1
            on_release:
                app.root.current = "main"
                root.manager.transition.direction = "left"
                root.manager.transition.duration = 1
 
<StorageWindow>:
name: "storage"
FloatLayout:
        Button:
            text: "Return to Main Menu"
font_size: 0.25, 0.25
            background_color : 1, 1, 1, 0
size_hint: 0.5, 0.5
pos_hint: {"x":0.1, "y":0.1}
            background_color: 1, 0, 0, 1
            on_release:
                app.root.current = "main"
                root.manager.transition.direction = "left"
root.manager.transition.duration = 1
Button:
text: "Access AI"
font_size: 0.25, 0.25
            background_color : 1, 1, 1, 0
size_hint: 0.5, 0.5
pos_hint: {"x":0.9, "y":0.9}
background_color: 1, 1, 0, 0
on_release:
app.root.current = "ai"
root.manager.transition.direction = "right"
root.manager.transition.duration = 1
<AIWindow>
name: "ai"
FloatLayout:
Button:
text: "Return to Storage"
background_color: 0, 1, 1, 0
on_release:
app.root.current = "storage"
root.manager.transition.direction = "left"
root.manager.transition.duration = 1
and the error
Traceback (most recent call last):
line 15, in <module>
kv = Builder.load_file("phoneassistant.kv") #links to kv file where graphics are loaded
line 305, in load_file
return self.load_string(data, **kwargs)
line 372, in load_string
parser = Parser(content=string, filename=fn)
line 483, in __init__
self.parse(content)
line 593, in parse
objects, remaining_lines = self.parse_level(0, lines)
line 756, in parse_level
if current_property[:3] == 'on_':
TypeError: 'NoneType' object is not subscriptable
I have tried changing the modules I use, such as changing to BoxLayout to see if that would work
And changed the on_press, to on_release, and sometimes tried to have both in my kv file
In addition, added transition to screen management class in kv file
Also created the def statements in the login, create, and main, classes on the main program
These were all mostly because I thought the main problem was the on_release button, however it's like likely also the structure of my code.

Answer 1

I didn't see where your code would create that error, but possibly your kivy file has an indentation problem somewhere. Something could be over-indented or else missing such that there is no object present. The code below is runnable but I don't think it has the layout polished as you intended. I took the liberty of adding a few example methods to your LoginWindow that I thought you may want to use.
I was not sure what was meant by reset() as you didn't have matching code for this so i changed this just to something that prints to the console.
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from kivy.lang import Builder
# screen manager is a widget dedicated to managing multiple screens for your application.
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.button import Button # creates the button in kivy
from kivy.uix.floatlayout import FloatLayout # means can place elements based on windows size
from kivy.config import Config
from kivy.properties import StringProperty, BooleanProperty, ListProperty, NumericProperty
from kivy.uix.popup import Popup
from kivy.uix.label import Label
from kivy.app import App
kv = Builder.load_string('''
# <ScreenManagement>:
# transition: SlideTransition
# LoginWindow:
# CreateAccountWindow:
# MainWindow:
# SettingsWindow:
# StorageWindow:
# AIWindow:
<LoginWindow>:
name: "login"
FloatLayout:
Button:
text: "Don't have an account?"
# font_size: 0.2, 0.1
background_color: 0, 0, 1, 1
size_hint: 0.4, 0.3
# pos: {"x":0.5, "y":0.25}
on_release:
root.manager.transition.direction = "left"
root.manager.transition.duration = 1
root.createBtn()
Button:
text: "Login here"
# font_size: 0.1, 0.2
background_color: 1, 0, 0, 1
size_hint: 0.4, 0.3
pos_hint: {"x":0.5, "y":0.75}
on_release:
root.manager.transition.direction = "right"
root.manager.transition.duration = 1
root.mainBtn()
<CreateAccountWindow>:
name: "create"
FloatLayout:
Button:
text: "Create login"
# font_size: 0.25, 0.25
background_color : 1, 1, 0, 1
size_hint: 0.5, 0.5
pos_hint: {"x":0.5, "y":0.1}
on_release:
app.root.current = "login"
root.manager.transition.direction = "right"
root.manager.transition.duration = 1
<MainWindow>:
name: "main"
FloatLayout:
Button:
text: "Return to login page"
# font_size: 0.25, 0.25
background_color : 1, 1, 0, 1
size_hint: 0.25, 0.35
pos_hint: {"x":0.5, "y":0.1}
on_release:
app.root.current = "login"
root.manager.transition.direction = "left"
root.manager.transition.duration = 1
Button:
text: "Access Settings"
# font_size: 0.5, 0.5
background_color : 1, 0, 1, 1
size_hint: 0.35, 40.5
pos_hint: {"x":0.1, "y":0.9}
on_release:
app.root.current = "settings"
root.manager.transition.direction = "right"
root.manager.transition.duration = 1
Button:
text: "Access Storage"
# font_size: 0.75, 0.75
background_color : 1, 1, 1, 0
size_hint: 0.45, 0.25
pos_hint: {"x":0.9, "y":0.5}
on_release:
app.root.current = "storage"
root.manager.transition.direction = "right"
root.manager.transition.duration = 1
<SettingsWindow>:
name: "settings"
FloatLayout:
Button:
text: "Return to Main Menu"
background_color: 0, 1, 1, 1
on_release:
app.root.current = "main"
root.manager.transition.direction = "left"
root.manager.transition.duration = 1
<StorageWindow>:
name: "storage"
FloatLayout:
Button:
text: "Return to Main Menu"
# font_size: 0.25, 0.25
background_color : 1, 1, 1, 0
size_hint: 0.5, 0.5
pos_hint: {"x":0.1, "y":0.1}
background_color: 1, 0, 0, 1
on_release:
app.root.current = "main"
root.manager.transition.direction = "left"
root.manager.transition.duration = 1
Button:
text: "Access AI"
# font_size: 0.25, 0.25
background_color : 1, 1, 1, 0
size_hint: 0.5, 0.5
pos_hint: {"x":0.9, "y":0.9}
background_color: 1, 1, 0, 0
on_release:
app.root.current = "ai"
root.manager.transition.direction = "right"
root.manager.transition.duration = 1
<AIWindow>
name: "ai"
FloatLayout:
Button:
text: "Return to Storage"
background_color: 0, 1, 1, 0
on_release:
app.root.current = "storage"
root.manager.transition.direction = "left"
root.manager.transition.duration = 1
''')
Config.set('graphics', 'resizable', True)
# creating classes for all screen on app help specify methods for individual screens using argument Screen
class LoginWindow(Screen, FloatLayout):
def on_pre_enter(self, *args):
print(" on pre-enter")
def on_enter(self, *args):
print("on enter")
def on_leave(self, *args):
print("login leave")
def on_pre_leave(self, *args):
print("pre-leave")
def reset(self):
print(f"reset {self}")
def mainBtn(self):
self.reset()
App.get_running_app().root.current = "main"
def createBtn(self):
self.reset()
App.get_running_app().root.current = "create"
class CreateAccountWindow(Screen, FloatLayout):
def reset(self):
print(f"{self}")
def loginBtn(self):
self.reset()
App.get_running_app().root.current = "login"
class MainWindow(Screen, FloatLayout):
def reset(self):
print(f"{self}")
def loginBtn(self):
self.reset()
App.get_running_app().root.current = "login"
def settingsBtn(self):
self.reset()
App.get_running_app().root.current = "settings"
def storageBtn(self):
self.reset()
App.get_running_app().root.current = "storage"
class SettingsWindow(Screen, FloatLayout):
pass
class StorageWindow(Screen, FloatLayout):
pass
class AIWindow(Screen, FloatLayout):
pass
class PhoneAssistantApp(App): # creates the app class
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.sm = ScreenManager() # sm will control moving between screens using the ScreenManager class
# gives the screens names
self.screens = (LoginWindow(name="login"), CreateAccountWindow(name="create"), MainWindow(name="main"),
SettingsWindow(name="settings"), StorageWindow(name="storage"), AIWindow(name="AI"))
def build(self) -> ScreenManager:
# adds the screens to the manager
for screen in self.screens:
self.sm.add_widget(screen)
# user to login page whenever program is ran
self.sm.current = "login"
return self.sm # returns screens when class is ran
if __name__ == "__main__":
PhoneAssistantApp().run()