如何从KivyMDTextField获取文本？

from kivy.lang import Builder
from kivy.base import runTouchApp
from kivymd.app import MDApp

KV = '''
BoxLayout:
    orientation: 'vertical'

    MDTextField:
        id: text_field
        hint_text: "Enter text"

    MDLabel:
        id: label
        text: ""

    MDRaisedButton:
        text: "Get Text"
        on_release: app.get_text()
'''


class TestApp(MDApp):
    def build(self):
        return Builder.load_string(KV)

    def get_text(self):
        text_field = self.root.ids.text_field
        label = self.root.ids.label

        text = text_field.text
        label.text = f"Text: {text}"


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