AttributeError: 'super' object has no attribute '__getattr__' KivyMD

Question

我正在学习 KivyMD，我正在尝试添加下拉菜单，但出现此错误。这可能是因为我对 id 的错误使用，但我仍然无法弄清楚。这是我的主要 py 代码：

from kivymd.app import MDApp
from kivy.lang import Builder
from kivymd.uix.screenmanager import ScreenManager
from kivymd.uix.screen import Screen
from kivymd.uix.menu import MDDropdownMenu

from kivy.metrics import dp
from kivy.core.window import Window

Window.size = (500, 800)

class HomePage(Screen):
    pass

class SecondPage(Screen):
    pass

class App(MDApp):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.screen = Builder.load_file("kivy.kv")
        items_d = ['Settings', 'Profile', 'Log Out', 'Exit']
        menu_items = [
            {
                "text": f"{i}",
                "viewclass": "OneLineListItem",
                "height": dp(40),
                "on_release": lambda x=f"{i}": self.menu_callback(x),
            } for i in items_d
        ]
        self.menu = MDDropdownMenu(
            caller = self.screen.ids.tool1,
            items = menu_items,
            width_mult =2
        )

    def menu_callback(self, text_item):
        print(text_item)
        self.menu.dismiss()

    def build(self):
        self.theme_cls.primary_palette = 'Red'
        self.theme_cls.primary_hue = '500'
        self.theme_cls.theme_style = 'Dark'

        sm = ScreenManager()
        sm.add_widget(HomePage(name='first'))
        sm.add_widget(SecondPage(name='second'))

        return self.screen
    

App().run()

这是 kv 文件：

#:kivy 2.1.0

ScreenManager:
    HomePage:
    SecondPage:

<HomePage>
    name: 'first'

    MDNavigationLayout:
        ScreenManager:
            Screen:
                BoxLayout:
                    orientation:'vertical'

                    MDTopAppBar:
                        id:tool1
                        title: 'Home Page'
                        left_action_items: [['menu', lambda x: nav_drawer.set_state('toggle')]]
                        right_action_items: [['dots-vertical'], lambda x: app.menu.open()]
                        elevation: 3

                    MDLabel:
                        text: "."

                    MDBottomAppBar:
                        MDTopAppBar:
                            icon: 'apps'
                            mode: 'center'
                            type: 'bottom'
                            

        MDNavigationDrawer:
            id: nav_drawer

            ScrollView:
                MDList:
                    OneLineIconListItem:
                        text: 'Home Page'
                        on_press: nav_drawer.set_state('close')
                        on_press: root.manager.current = 'first'

                        IconLeftWidgetWithoutTouch:
                            icon:'bluetooth'

                    OneLineIconListItem:
                        text: 'Content Page'
                        on_press: root.manager.current = 'second'
                        on_press: nav_drawer.set_state('close')
                                
                        IconLeftWidgetWithoutTouch:
                            icon:'content-copy'


<SecondPage>
    name: 'second'

    MDNavigationLayout:
        ScreenManager:
            Screen:
                BoxLayout:
                    orientation:'vertical'

                    MDTopAppBar:
                        id:tool1
                        title: 'Content Page'
                        left_action_items: [['menu', lambda x: nav_drawer.set_state('toggle')]]
                        right_action_items: [['dots-vertical'], lambda x: app.menu.open()]
                        elevation: 3

                    MDLabel:
                        text: "."

                    MDBottomAppBar:
                        MDTopAppBar:
                            type: 'bottom'
                            icon: 'apps'
                            mode: 'center'
                            left_action_items: [['information']]

        MDNavigationDrawer:
            id: nav_drawer

            ScrollView:
                MDList:
                    OneLineIconListItem:
                        text: 'Home Page'
                        on_press: nav_drawer.set_state('close')
                        on_press: root.manager.current = 'first'

                        IconLeftWidgetWithoutTouch:
                            icon:'bluetooth'

                    OneLineIconListItem:
                        text: 'Second Page'
                        on_press: nav_drawer.set_state('close')
                        on_press: root.manager.current = 'second'

                        IconLeftWidgetWithoutTouch:
                            icon:'wifi'

我不知道为什么，但可能是因为 self.screen 并不真正包含 ids？ 如果我使用了错误的方法，请告诉我应该使用什么。

Answer 1

您正在错误地尝试访问

tool1

id

。首先，请注意，在

ids

文件中定义的

kv

成为定义该

ids

的规则根的

id

字典的一部分。所以

tool1

id

（定义两次）最终出现在

ids

的

HomePage

和

ids

的

SecondPage

中。所以你必须通过包含对象引用那个

id

。假设你想引用

tool1

中定义的

HomePage

，只需更改：

caller = self.screen.ids.tool1,

至：

caller = self.screen.get_screen('first').ids.tool1,

不相关，但你可以删除这些行：

    sm = ScreenManager()
    sm.add_widget(HomePage(name='first'))
    sm.add_widget(SecondPage(name='second'))

因为他们的结果未被使用。