AttributeError：“屏幕”对象在 Python KivyMD 中没有属性“文本”

Question

Python 3.9.0

KivyMD 0.104.2.dev0

预期目标

所以我想根据芯片的文本是否存在于名为list1的列表中来清除一些MDChips，但是这样做会出现以下错误

问题

当我尝试使用 def clear(self) 函数访问小部件树时，我不断收到错误，但我不断收到上述错误

我发现在下面的 kv 字符串中使用 Screen : 会给我上面提到的错误（在标题中提到）。

button = '''
Screen:
    MDRaisedButton:
        id: button_id
        text: "PRESS ME"
        pos_hint: {"center_x": .35, "center_y": .8}
        on_release: app.drop.open()
'''

但是，如果我删除 Screen :，那么由于某种原因，使用 open() 调用 MDDropDownMenu 小部件时会引发以下错误：

AttributeError: 'super' 对象没有属性 '__ getattr __'

代码

from kivy.lang import Builder
from kivymd.uix.screen import Screen
from kivymd.app import MDApp
from kivymd.uix.menu import MDDropdownMenu
from kivymd.uix.chip import MDChip
from kivymd.uix.floatlayout import FloatLayout

button = '''
Screen:
    MDRaisedButton:
        id: button_id
        text: "PRESS ME"
        pos_hint: {"center_x": .35, "center_y": .8}
        on_release: app.drop.open()
'''

button1 = '''
Screen:
    MDRaisedButton:
        id: button1_id
        text: "PRESS ME 2"
        pos_hint: {"center_x": .5, "center_y": .8}
        on_release: app.clear()
'''

list1 = (['Item 1','Item 2','Item 3'], ['Item 4', 'Item 5', 'Item 6'])
class Test(MDApp):
    def build(self):
        self.screen = Screen()
        self.btn = Builder.load_string(button)
        self.btn1 = Builder.load_string(button1)

        self.screen.add_widget(self.btn1)
        self.screen.add_widget(self.btn)


        self.drop = MDDropdownMenu(
            caller = self.btn.ids.button_id,
            items = [{'text':'Show Chips'}],
            width_mult = 4,
        )
        self.drop.bind(on_release=self.testing)

        return self.screen
    
    def testing(self, menu, menu_item):
        objects = {0.2 : "Item 1", 0.5 : "Item 2", 0.8 : "Item 3"}
        for pos, item in objects.items():
            self.chip = MDChip(
                text = item,
                check = True,
                pos_hint = {"center_x":pos, "center_y":0.4},
                
            )
            self.screen.add_widget(self.chip)

    def clear(self):
        for child in self.root.children[:]:
            if child.text in list1[0]:
                self.root.remove_widget(child)

Test().run()

错误

Traceback (most recent call last):
   File "e:\Projects\Workout Planner\Planner v_1\My_Project\Test\test.py", line 61, in <module>
     Test().run()
   File "C:\Users\Mocha\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\app.py", line 949, in run
     self._run_prepare()
   File "C:\Users\Mocha\AppData\Local\Programs\Python\Python39\lib\site-packages\kivy\app.py", line 919, in _run_prepare
     root = self.build()
   File "e:\Projects\Workout Planner\Planner v_1\My_Project\Test\test.py", line 37, in build
     caller = self.btn.ids.button_id,
   File "kivy\properties.pyx", line 864, in kivy.properties.ObservableDict.__getattr__
 AttributeError: 'super' object has no attribute '__getattr__'
PS E:\Projects\Workout Planner\Planner v_1\My_Project>

Answer 1

虽然我不知道为什么它在我之前发布的代码中不起作用的正确原因，但我已经找到了解决问题的方法

解决方案：

您必须构建另一个继承自Screen 的类。 然后在这个新类中输入/复制您希望在应用程序中拥有的所有内容。

在继承自 MDApp 的 Class 中，您可以指定您想要的主题并返回继承自 Screen 的 Class

此外，在将所有小部件转移到继承自 Screen 的类之后，请确保将此类称为 root 而不是 app，只要您将功能绑定到按钮或使用它做其他事情。

解决方案代码：

from kivy.lang import Builder
from kivymd.uix.screen import Screen
from kivymd.app import MDApp
from kivymd.uix.menu import MDDropdownMenu
from kivymd.uix.chip import MDChip
from kivymd.uix.floatlayout import FloatLayout

Builder.load_string(
    """
<BuildApp>:

    MDRaisedButton:
        id: button_id
        text: "PRESS ME"
        pos_hint: {"center_x": .35, "center_y": .8}
        on_release: root.drop.open()

    MDRaisedButton:
        id: button1_id
        text: "PRESS ME 2"
        pos_hint: {"center_x": .5, "center_y": .8}
        on_release: root.clear()
        
    """
)#reference should be as root.function_name(),


list1 = (['Item 1','Item 2','Item 3'], ['Item 4', 'Item 5', 'Item 6'])

class BuildApp(Screen):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)

        self.drop = MDDropdownMenu(
            caller = self.ids.button_id,   #use self.id.id_name
            items = [{'text':'Show Chips'}],
            width_mult = 4,
        )
        self.drop.bind(on_release=self.show_chips)
    
    def show_chips(self, menu, menu_item):
        objects = {0.2 : "Item 1", 0.5 : "Item 2", 0.8 : "Item 3"}
        for pos, item in objects.items():
            self.chip = MDChip(
                text = item,
                check = True,
                pos_hint = {"center_x":pos, "center_y":0.4},
                
            )
            self.add_widget(self.chip)

    def clear(self):
        for child in self.children[:]:
            if child.text in list1[0]:
                self.remove_widget(child)

class Test(MDApp):
    def build(self):
        return BuildApp()

    
    

Test().run()

Reference