How to change label by id kivy?

Question

Python

There is a small code.

from kivy.lang import Builder
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout

Builder.load_string("""
<Gex>:
  orientation: 'vertical'
  Button:
    text: 'UwU'
    on_press: root.upd
  Label:
    id: fer
    text: ' '
""")
class Gex(BoxLayout):
 def upd(self):
  self.ids.fer.text = ':<'

class FakeApp(App):
 def build(self):
  return Gex()

FakeApp().run()

I don’t know what I’m doing wrong, but it doesn’t give an error, but it doesn’t change anything either. If you turn to Gex.upd, then he does not find it.

Answer 1

1. on_press: root.upd()
2.self.ids['fer'].text = ':<'

from kivy.lang import Builder
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout

Builder.load_string("""
<Gex>:
  orientation: 'vertical'
  Button:
    text: 'UwU'
    on_press: root.upd()
  Label:
    id: fer
    text: ' '
""")
class Gex(BoxLayout):
 def upd(self):
  self.ids['fer'].text = ':<'

class FakeApp(App):
 def build(self):
  return Gex()

FakeApp().run()