Recreating kivy app with scrollview to be used as screen with screenmanager - kivy

Question

I've been trying to use scrollview in a screen, that will be used as part of an app and I managed to find the following code that creates an app with scrollview. But I'm not able to change it into screen class.
Here is the python code:
from kivy.app import App
from kivy.uix.button import Button
class ScrollButton(Button):
pass
class TestApp(App):
def build(self):
super(TestApp, self).build()
container = self.root.ids.container
for i in range(30):
container.add_widget(ScrollButton(text=str(i)))
return self.root
if __name__ == '__main__':
TestApp().run()
.kv file
ScreenManager:
Screen:
ScrollView:
size_hint: None, None
size: 600, 320
pos_hint: {'center_x': .5, 'center_y': .5}
GridLayout:
cols: 1
padding: 10
spacing: 10
height: self.minimum_height
size_hint: None, None
do_scroll_x: False
id: container
<ScrollButton>
size_hint: None, None
size: 600, 40
I would appreciate if anybody could show how to do it/give me some directions on how to change this to fit my purpose. Any alternative way of doing this is also welcome.

Answer 1

Many people recommend making the ScreenManager in the build method in the python file instead, here's how to do that:
Python
from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang.builder import Builder
Builder.load_file("styling.kv")
class ScrollButton(Button):
pass
class MainScreen(Screen):
def on_kv_post(self, instance):
container = self.ids['container']
for i in range(30):
container.add_widget(ScrollButton(text=str(i)))
class TestApp(App):
def build(self):
sm = ScreenManager()
sm.add_widget(MainScreen())
return sm
if __name__ == '__main__':
TestApp().run()
Kivy
<ScrollButton>:
size_hint: None, None
size: 600, 40
<MainScreen>:
name: 'MainScreen'
ScrollView:
size_hint: None, None
size: 600, 320
pos_hint: {'center_x': .5, 'center_y': .5}
GridLayout:
cols: 1
padding: 10
spacing: 10
height: self.minimum_height
size_hint: None, None
do_scroll_x: False
id: container
Changes made
ScreenManager made in .py instead of .kv
Created Screen class in .py, so we can use python methods from the Screen
Widget adding moved to the Screen's class, using on_kv_post (this method is fired only one time when the Screen is ready)
Made the screen a template class instead of an object in .kv which the Screen in the python file uses to make the final Screen
PS: This is how it's usually done