Kivy中id为list_view的组件无法被Python代码识别的问题求助

我正在尝试在主屏幕上动态创建OneLineListItem，但id list_view一直无法被识别。我试了很多方法，都没找到解决办法。

我的Python代码（main.py） #

from kivy.uix.boxlayout import BoxLayout
from kivy.properties import ObjectProperty
from kivy.uix.screenmanager import ScreenManager, Screen
from kivymd.app import MDApp
from kivymd.uix.dialog import MDDialog
from kivymd.uix.button import MDFlatButton
from kivymd.uix.list import OneLineListItem


class CustomDialogContent(MDGridLayout):
    pass


class Content(BoxLayout):
    manager = ObjectProperty()
    nav_drw = ObjectProperty()
    pass


class Demo(ScreenManager):
    pass


class Main(MDApp):
    def build(self):
        return Demo()

    def show_dialog(self):
        close_button = MDFlatButton(text='Close', pos_hint={'x': 0, 'y': -.3}, on_release=self.close_dialog)
        ok_button = MDFlatButton(text='OK', pos_hint={'x': 0, 'y': -.3}, on_release=self.ok_dialog)
        self.dialog = MDDialog(
            title="Dialog Title",
            size_hint=(0.8, 0.3),
            type="custom",
            content_cls=CustomDialogContent(),
            buttons=[ok_button, close_button],
            auto_dismiss=False
        )
        self.dialog.open()

    # 问题核心区域
    def post_text(self, text1, text2, *args):
        print(text1)
        print(text2)
        if text1:
            screen = self.root.ids.screen_manager.get_screen("First")
            # 这里报错找不到list_view这个id
            screen.ids.list_view.add_widget(OneLineListItem(text=text1))
            screen.ids.list_view.add_widget(OneLineListItem(text=text2))
            # 下面注释的写法也尝试过，同样无效
            # self.ids.list_view.add_widget(OneLineListItem(text=text1))
            # self.ids.list_view.add_widget(OneLineListItem(text=text1))

    def ok_dialog(self, *args):
        text_field_1 = self.dialog.content_cls.ids.text_field_1
        text_field_2 = self.dialog.content_cls.ids.text_field_2
        self.post_text(text_field_1.text, text_field_2.text)
        self.close_dialog()

    def close_dialog(self, *args):
        self.dialog.dismiss()


Main().run()

我的KV代码（main.kv） #

#: import NoTransition kivy.uix.screenmanager.NoTransition

<CustomDialogContent>
    rows: 2
    spacing: '12dp'
    padding: '12dp'
    size_hint_y: None
    height: '120dp'

    MDTextField:
        id: text_field_1
        size_hint_x: .5
        hint_text: "Text Field 1"

    MDTextField:
        id: text_field_2
        size_hint_x: .5
        hint_text: "Text Field 2"

<Content>:
    ScrollView:
        MDList:
            OneLineListItem:
                text: "Go to screen 1"
                on_release:
                    root.manager.transition = NoTransition()
                    root.manager.current  = "First"

            OneLineListItem:
                text: "Go to screen 2"
                on_release:
                    root.manager.transition = NoTransition()
                    root.manager.current  = "Second"

<Demo>:
    Screen:
        MDTopAppBar:
            pos_hint: {"top": 1}
            elevation: 8
            left_action_items: [["menu",lambda x: nav_drawer.set_state("open")]]

        FloatLayout:
            MDTextField:
                hint_text: "Search"
                max_text_length: 15
                size_hint_x: 0.425
                line_color_focus: 0.92, 0.25, 0.20
                hint_text_color_normal: "red"
                text_color_focus: '#ff0000'
                text_color_normal: '#00ff00'
                pos_hint: {"right": 1.0, "top": 1.0}

            MDNavigationDrawer:
                id: nav_drawer
                Content:
                    manager: screen_manager
                    nav_drw: nav_drawer

            MDNavigationLayout:
                ScreenManager:
                    id: screen_manager

                    Screen:
                        id: main_screen
                        name: "First"

                        MDLabel:
                            text: "First Screen"

                        MDList:
                            id: list_view
                            name: "list_view"

                        MDIconButton:
                            icon:'android'
                            pos_hint: {"y":0.1, "x": 0.8}
                            on_release:
                                app.show_dialog()

                    Screen:
                        name: "Second"
                        MDLabel:
                            text: "2nd Screen"

报错信息 #

File "kivy\properties.pyx", line 961, in kivy.properties.ObservableDict.__getattr__
KeyError: 'list_view'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\addyi\PycharmProjects\KivyApp2\main.py", line 73, in <module>
    Main().run()
  File "C:\Users\addyi\PycharmProjects\TestApp\venv\lib\site-packages\kivy\app.py", line 955, in run
    runTouchApp()
  File "C:\Users\addyi\PycharmProjects\TestApp\venv\lib\site-packages\kivy\base.py", line 574, in runTouchApp
    EventLoop.mainloop()
  File "C:\Users\addyi\PycharmProjects\TestApp\venv\lib\site-packages\kivy\base.py", line 339, in mainloop
    self.idle()
  File "C:\Users\addyi\PycharmProjects\TestApp\venv\lib\site-packages\kivy\base.py", line 383, in idle
    self.dispatch_input()
  File "C:\Users\addyi\PycharmProjects\TestApp\venv\lib\site-packages\kivy\base.py", line 334, in dispatch_input
    post_dispatch_input(*pop(0))
  File "C:\Users\addyi\PycharmProjects\TestApp\venv\lib\site-packages\kivy\base.py", line 302, in post_dispatch_input
    wid.dispatch('on_touch_up', me)
  File "kivy\_event.pyx", line 731, in kivy._event.EventDispatcher.dispatch
  File "C:\Users\addyi\PycharmProjects\TestApp\venv\lib\site-packages\kivymd\uix\button\button.py", line 1187, in on_touch_up
    return super().on_touch_up(touch)
  File "C:\Users\addyi\PycharmProjects\TestApp\venv\lib\site-packages\kivymd\uix\behaviors\ripple_behavior.py", line 404, in on_touch_up
    return super().on_touch_up(touch)
  File "C:\Users\addyi\PycharmProjects\TestApp\venv\lib\site-packages\kivy\uix\behaviors\button.py", line 179, in on_touch_up
    self.dispatch('on_release')
  File "kivy\_event.pyx", line 727, in kivy._event.EventDispatcher.dispatch
  File "kivy\_event.pyx", line 1307, in kivy._event.EventObservers.dispatch
  File "kivy\_event.pyx", line 1231, in kivy._event.EventObservers._dispatch
  File "C:\Users\addyi\PycharmProjects\KivyApp2\main.py", line 65, in ok_dialog
    self.post_text(text_field_1.text, text_field_2.text)
  File "C:\Users\addyi\PycharmProjects\KivyApp2\main.py", line 53, in post_text
    screen.ids.list_view.add_widget(OneLineListItem(text=text1))
  File "kivy\properties.pyx", line 964, in kivy.properties.ObservableDict.__getattr__
AttributeError: 'super' object has no attribute '__getattr__'

可以看到list_view已经在名为"First"的Screen里定义了，但代码就是识别不到这个id，有没有大佬能帮我排查下问题出在哪？

备注：内容来源于stack exchange，提问作者SupEldrix