Python KivyMD：如何使toggle_nav_drawer（）函数工作？

我的kv代码有问题。我想创建一个带有几个导航抽屉按钮的

MDNavigationDrawer

。窗口显示出来，但当我单击MDToolbar时，程序崩溃并显示此错误消息

 Traceback (most recent call last):
   File "C:/Users/path/to/my/file/main.py", line 189, in <module>
     KivyGUI().run()
   File "C:\Users\uname\Anaconda3\lib\site-packages\kivy\app.py", line 855, in run
     runTouchApp()
   File "C:\Users\uname\Anaconda3\lib\site-packages\kivy\base.py", line 504, in runTouchApp
     EventLoop.window.mainloop()
   File "C:\Users\uname\Anaconda3\lib\site-packages\kivy\core\window\window_sdl2.py", line 746, in mainloop
     self._mainloop()
   File "C:\Users\uname\Anaconda3\lib\site-packages\kivy\core\window\window_sdl2.py", line 478, in _mainloop
     EventLoop.idle()
   File "C:\Users\uname\Anaconda3\lib\site-packages\kivy\base.py", line 342, in idle
     self.dispatch_input()
   File "C:\Users\uname\Anaconda3\lib\site-packages\kivy\base.py", line 327, in dispatch_input
     post_dispatch_input(*pop(0))
   File "C:\Users\uname\Anaconda3\lib\site-packages\kivy\base.py", line 293, in post_dispatch_input
     wid.dispatch('on_touch_up', me)
   File "kivy\_event.pyx", line 707, in kivy._event.EventDispatcher.dispatch
   File "C:\Users\uname\Anaconda3\lib\site-packages\kivymd\ripplebehavior.py", line 84, in on_touch_up
     return super().on_touch_up(touch)
   File "C:\Users\uname\Anaconda3\lib\site-packages\kivymd\button.py", line 480, in on_touch_up
     return super().on_touch_up(touch)
   File "C:\Users\uname\Anaconda3\lib\site-packages\kivy\uix\behaviors\button.py", line 179, in on_touch_up
     self.dispatch('on_release')
   File "kivy\_event.pyx", line 703, in kivy._event.EventDispatcher.dispatch
   File "kivy\_event.pyx", line 1214, in kivy._event.EventObservers.dispatch
   File "kivy\_event.pyx", line 1138, in kivy._event.EventObservers._dispatch
   File "C:\Users\path\to\my\file\design.kv", line 59, in <lambda>
     left_action_items: [['dots-vertical', lambda x: root.toggle_nav_drawer()]]
   File "kivy\weakproxy.pyx", line 32, in kivy.weakproxy.WeakProxy.__getattr__
 AttributeError: 'LayoutPy' object has no attribute 'toggle_nav_drawer'

我剪切了大量的Python代码，因此对您来说更加清晰。我不认为这是模块本身的问题，因为它对我来说很好（这也是我运行它时解决方案的样子）。我认为问题在于我的

LayoutPy

类继承自

FloatLayout

，它没有

toggle\u nav\u drawer

对象。。。但是我现在不知道如何在我现有的代码中实现一个合适的解决方案（我现在正在尝试两天）。如果您需要整个代码（在添加

NavigationDrawer

之前，一切都很好），您可以查看一下

非常感谢

错误-属性错误 根本原因 对象

LayoutPy

没有属性

toggle\u nav\u drawer

，因为

toggle\u nav\u drawer

是在

LayoutPy

的实例化子对象

NavigationLayout:

中定义的

解决方案 将

root.toggle\u nav\u drawer（）

替换为

root.ids.nav\u布局。toggle\u nav\u drawer（）

代码片段-kv文件 输出

---

我想你是真正回答我的任何问题的人

#:kivy 1.11.0
#:import MDNavigationDrawer kivymd.navigationdrawer.MDNavigationDrawer
#:import NavigationLayout kivymd.navigationdrawer.NavigationLayout
#:import NavigationDrawerDivider kivymd.navigationdrawer.NavigationDrawerDivider
#:import NavigationDrawerToolbar kivymd.navigationdrawer.NavigationDrawerToolbar
#:import NavigationDrawerSubheader kivymd.navigationdrawer.NavigationDrawerSubheader
#:import MDToolbar kivymd.toolbar.MDToolbar

<ContentNavigationDrawer@MDNavigationDrawer>:
    drawer_logo: 'src/LinguIcon.png'

    NavigationDrawerSubheader:
        text: "Menu:"

<LayoutPy>:
    orientation: 'vertical'
    scr_mngr: scr_mngr

    NavigationLayout:
        id: nav_layout

        ContentNavigationDrawer:
            id: nav_drawer
            name: 'nav_drawer'

            NavigationDrawerToolbar:
                title: 'Options'

            NavigationDrawerIconButton:
                icon: 'settings'
                text: 'Select Language'
                on_release: root.open2ndScreen('screen_card')

            NavigationDrawerIconButton:
                icon: 'close'
                text: 'Exit'
                on_release: root.exit()

            NavigationDrawerIconButton:
                icon: 'face'
                text: 'Contact the developer'
                on_release: root.sendDevHint()

        BoxLayout:
            orientation: 'vertical'

            MDToolbar:
                id: toolbar
                title: 'Menu'
                md_bg_color: app.theme_cls.primary_color
                background_palette: 'Primary'
                background_hue: '500'
                left_action_items: [['dots-vertical', lambda x: root.toggle_nav_drawer()]]

            Widget:

    ScreenManager:
        id: scr_mngr
        screen_main: screen_main

        Screen:
            id: screen_main
            name: 'screen_main'
            input_words: input_words
            lbl: lbl
            btn: btn

            FloatLayout:

                ### A few widgets ### 

        Screen:
            id: screen_card
            name: 'screen_card'

            FloatLayout:

                ### A few widgets ###

import sys
import kivy
from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.boxlayout import BoxLayout
from kivy.core.window import Window
from kivymd.theming import ThemeManager
from kivymd.label import MDLabel
from kivymd.textfields import MDTextField, MDTextFieldClear, MDTextFieldRect, MDTextFieldRound
from kivy.lang import Builder
from kivymd.navigationdrawer import MDNavigationDrawer, NavigationDrawerIconButton, NavigationLayout
from kivy.properties import ObjectProperty
from kivymd.toast import toast

kivy.require('1.11.0')

class LayoutPy(FloatLayout):
    def __init__(self, **kwargs):
        super(LayoutPy, self).__init__(**kwargs)
        self.scr_mngr = ObjectProperty(None)
        self.build_nav_btns()

    def callback(self, instance, value):
        toast("Pressed item menu %d" % value)

    def exit(self):
        sys.exit(1)

    def build_nav_btns(self):
        btns = ["Select Language", "Contact the developer", "Exit"]
        for count, btn in enumerate(btns):
            if count == 1:
                self.ids.nav_drawer.add_widget(
                NavigationDrawerIconButton(
                    icon='settings', text=btn,
                    on_release=lambda x, btn: self.callback(x, btn)))
            elif count == 2:
                self.ids.nav_drawer.add_widget(
                NavigationDrawerIconButton(
                    icon='face', text=btn,
                    on_release=lambda x, btn: self.callback(x, btn)))
            elif count == 3:
                self.ids.nav_drawer.add_widget(
                NavigationDrawerIconButton(
                    icon='close', text=btn,
                    on_release=lambda x: self.exit()))

Builder.load_file("design.kv")

class KivyGUI(App):
    theme_cls = ThemeManager()
    theme_cls.primary_palette = ("Teal")
    title = ("App")

    def build(self):
        c = LayoutPy()
        return c


if __name__ == "__main__":
    KivyGUI().run()

     left_action_items: [['dots-vertical', lambda x: root.toggle_nav_drawer()]]
   File "kivy\weakproxy.pyx", line 32, in kivy.weakproxy.WeakProxy.__getattr__
 AttributeError: 'LayoutPy' object has no attribute 'toggle_nav_drawer'

BoxLayout:
    orientation: 'vertical'

    MDToolbar:
        id: toolbar
        title: 'Menu'
        md_bg_color: app.theme_cls.primary_color
        background_palette: 'Primary'
        background_hue: '500'
        left_action_items: [['dots-vertical', lambda x: root.ids.nav_layout.toggle_nav_drawer()]]