MDDropdownMenu的调用方上的KivyMD KeyError

问题描述

我正在尝试更改现有的Kivy App，以合并外观漂亮的KivyMD小部件。我删除了Spinner的{​​{1}}和MDRaisedButton的{​​{1}} on_release，并删除了已通过蓝牙与设备配对的设备名称列表（具体取决于在平台上）。对于此测试示例，我仅使用caller文档示例中所示的菜单项列表。

由于某种原因，在初始化MDDropdownMenu属性时，我收到了MDDropdownMenu KeyError: 'dev_button'的{​​{1}}。 MDRaisedButton方法在我的根类中，该类位于名为id和MDDropdownMenu的文件__init__和indexui.py的单独文件中。但是已导入indexui.kv文件中并包含在main.py文件中。该应用程序确实在更改main.kv之前运行。

indexui.py

main.py

indexui.kv

main.kv

main.py

Spinner

main.kv

class RootLay(FloatLayout):
    this = ObjectProperty(None)  # App object
    bserial = ObjectProperty(None)  # Bluetooth variables starts
    recv_stream = ObjectProperty(None)
    send_stream = ObjectProperty(None)
    menu = ObjectProperty(None)
    rfsocket = ObjectProperty(None)
    device = ObjectProperty(None)
    pattern = ObjectProperty(None)
    def __init__(self,**kwargs):
        super().__init__(**kwargs)
        self.device = None
        self.pattern = re.compile(r'[GNSTUkg,\s]')
        self.dev_list = []
        menu_items = [{"icon": "git","text": f"Item {i}"} for i in range(5)]
        print(dir(self.ids))
        self.menu = MDDropdownMenu(
            caller=self.ids.dev_button,items=menu_items,width_mult=4
        )
        self.menu.bind(on_release=self.menu_callback)

有人可以帮我理解为什么会有<RootLay>: MDToolbar: pos_hint: {'top': 1,'right': 1} title: "Bluetooth Weigh" MDRaisedButton: id: dev_button text: "SEE DEVICES" pos_hint: {'top': 0.76,'right': 0.9} on_release: app.root.menu.open() 吗？ from kivymd.app import MDApp from views.indexui import RootLay from kivy.properties import ObjectProperty class MainApp(MDApp): def build(self): self.theme_cls.primary_palette = "Yellow" # "Purple","Red" self.theme_cls.primary_hue = "600" # self.icon = 'bluetooth-connected_326502.png' root = ObjectProperty(RootLay()) return root def on_pause(self): return True MainApp().run() 作为方法在#:include views/indexui.kv RootLay: 类范围内。因此，我应该能够访问其所有属性。

解决方法

我认为问题在于您正在尝试访问ids类的RootLay，然后才能使用它们。我建议像这样使用Clock.schedule_once()来延迟访问：

class RootLay(FloatLayout):
    this = ObjectProperty(None)  # App object
    bserial = ObjectProperty(None)  # Bluetooth variables starts
    recv_stream = ObjectProperty(None)
    send_stream = ObjectProperty(None)
    menu = ObjectProperty(None)
    rfsocket = ObjectProperty(None)
    device = ObjectProperty(None)
    pattern = ObjectProperty(None)
    def __init__(self,**kwargs):
        super().__init__(**kwargs)
        self.device = None
        self.pattern = re.compile(r'[GNSTUkg,\s]')
        self.dev_list = []
        Clock.schedule_once(self.setup_menu)  # delay until ids are available

    def setup_menu(self,dt):
        menu_items = [{"icon": "git","text": f"Item {i}"} for i in range(5)]
        self.menu = MDDropdownMenu(
            caller=self.ids.dev_button,items=menu_items,width_mult=4
        )
        self.menu.bind(on_release=self.menu_callback)