How to change the text in Label on button click?

Question

Python

How can I change the text in the label when the button is clicked?

import kivy

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


class TestApp(App):

    def build(self):
        bl = BoxLayout
        bl.add_widget(Button(text="Hello"))
        bl.add_widget(Label(text="Hello World"))


if __name__ == '__main__':
    TestApp().run()

Answer 1

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


class TestApp(App):

    def change_text(self, instance):
        self.label.text = "Text Was Changed"

    def build(self):
        bl = BoxLayout()
        self.label = Label(text="Hello World")
        bl.add_widget(Button(text="Hello", on_press=self.change_text))
        bl.add_widget(self.label)

        return bl

if __name__ == '__main__':
    TestApp().run()

1. It is necessary to add the instance argument to the function.
2. In order to be able to change the text when the button is pressed, it is necessary not immediately through Add_Widget, but first add it to a variable, you must put .self before the variable name to change the text