Python 无法从kivy对象获取ID

我正在尝试将ids与

ObjectProperty（）

一起使用，但工作方式与think不同。我理解ObjectProperty的方式是将

variablename=ObjectProperty（）

作为对.kv文件中名为variablename的类的引用，但我误解了一些东西，因为我得到了以下错误：

swiper\u manager=MySwiperManager.ids.swiper\u manager
AttributeError:'kivy.properties.ObjectProperty'对象没有属性'id'

.py文件

from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import Screen
from kivy.properties import ObjectProperty
from kivy.lang import Builder

from kivymd.uix.managerswiper import MDSwiperPagination
from kivymd.theming import ThemeManager

Builder.load_file("Prelogin/prescreenmanger.kv")

class MySwiperManager(BoxLayout):
    pass

class PreScreenManager(Screen):
    theme_cls = ThemeManager()
    theme_cls.primary_palette = 'Indigo'
    MySwiperManager = ObjectProperty()
    swiper_manager = MySwiperManager.ids.swiper_manager
    paginator = MDSwiperPagination()
    paginator.screens = swiper_manager.screen_names
    paginator.manager = swiper_manager
    swiper_manager.paginator = paginator
    MySwiperManager.add_widget(paginator)

from kivy.uix.boxlayout import BoxLayout
from kivy.app import App
from kivy.uix.screenmanager import Screen
from kivy.properties import ObjectProperty
from kivy.lang import Builder

from kivymd.uix.managerswiper import MDSwiperPagination
from kivymd.theming import ThemeManager

Builder.load_file("Prelogin/prescreenmanger.kv")

class MySwiperManager(BoxLayout):
    pass

class PreScreenManager(Screen):
    swiper_manager = ObjectProperty()  # reference to MySwiperManager from kv file

    def do_setup(self, dt):
        # code to do the setup (called after App is instantiated)
        paginator = MDSwiperPagination()
        paginator.screens = self.swiper_manager.screen_names
        paginator.manager = self.swiper_manager
        self.swiper_manager.paginator = paginator
        self.swiper_manager.add_widget(paginator)

.kv文件

<ScreenOne@Screen>:
    name: 'screen one'
    Label: 
        text: 'Hello World'

<ScreenTwo@Screen>:
    name: 'screen two'


<ScreenThree@Screen>:
    name: 'screen three'


<ScreenFour@Screen>:
    name: 'screen four'



<ScreenFive@Screen>:
    name: 'screen five'


<PreScreenManager>:
    MySwiperManager:
        orientation: 'vertical'
        id: MySwiperManager

        MDSwiperManager:
            id: swiper_manager

            ScreenOne: 

            ScreenTwo:

            ScreenThree:

            ScreenFour:

            ScreenFive:

<ScreenOne@Screen>:
    name: 'screen one'
    Label: 
        text: 'Hello World'
        color: 1,1,1

<ScreenTwo@Screen>:
    name: 'screen two'


<ScreenThree@Screen>:
    name: 'screen three'


<ScreenFour@Screen>:
    name: 'screen four'


<ScreenFive@Screen>:
    name: 'screen five'


<PreScreenManager>:
    swiper_manager: swiper_manager  # uses the id from below

    MySwiperManager:
        orientation: 'vertical'

        MDSwiperManager:
            id: swiper_manager

            ScreenOne:

            ScreenTwo:

            ScreenThree:

            ScreenFour:

            ScreenFive:

主电压（千伏）

AnchorLayout:
    canvas.before:
        Rectangle:
            size: self.size
            pos: self.pos
            source: "Start/Background.png"   
    anchor_x: 'center'
    anchor_y: 'top'
    Image:
        source: 'Start/Loginlogo.png'
        keep_ratio: False
        allow_stretch: True
        opacity: 1
        size_hint: 1, 0.25
        pos_hint: (0,0)  
    ScreenManager:
        id: screen_manager
        PreScreenManager:
            id: PreScreenManager

AnchorLayout:
    canvas.before:
        Rectangle:
            size: self.size
            pos: self.pos
            source: "Start/Background.png"   
    anchor_x: 'center'
    anchor_y: 'top'
    Image:
        source: 'Start/Loginlogo.png'
        keep_ratio: False
        allow_stretch: True
        opacity: 1
        size_hint: 1, 0.25
        pos_hint: (0,0)  
    ScreenManager:
        id: screen_manager
        PreScreenManager:
            id: PreScreenManager

---

这是我的代码的更新版本。 .py文件

from kivy.uix.boxlayout import BoxLayout
from kivy.app import App
from kivy.uix.screenmanager import Screen
from kivy.properties import ObjectProperty
from kivy.lang import Builder

from kivymd.uix.managerswiper import MDSwiperPagination
from kivymd.theming import ThemeManager

Builder.load_file("Prelogin/prescreenmanger.kv")

class MySwiperManager(BoxLayout):
    pass

class PreScreenManager(Screen):
    swiper_manager = ObjectProperty()  # reference to MySwiperManager from kv file

    def do_setup(self, dt):
        # code to do the setup (called after App is instantiated)
        paginator = MDSwiperPagination()
        paginator.screens = self.swiper_manager.screen_names
        paginator.manager = self.swiper_manager
        self.swiper_manager.paginator = paginator
        self.swiper_manager.add_widget(paginator)

.kv文件

<ScreenOne@Screen>:
    name: 'screen one'
    Label: 
        text: 'Hello World'

<ScreenTwo@Screen>:
    name: 'screen two'


<ScreenThree@Screen>:
    name: 'screen three'


<ScreenFour@Screen>:
    name: 'screen four'



<ScreenFive@Screen>:
    name: 'screen five'


<PreScreenManager>:
    MySwiperManager:
        orientation: 'vertical'
        id: MySwiperManager

        MDSwiperManager:
            id: swiper_manager

            ScreenOne: 

            ScreenTwo:

            ScreenThree:

            ScreenFour:

            ScreenFive:

<ScreenOne@Screen>:
    name: 'screen one'
    Label: 
        text: 'Hello World'
        color: 1,1,1

<ScreenTwo@Screen>:
    name: 'screen two'


<ScreenThree@Screen>:
    name: 'screen three'


<ScreenFour@Screen>:
    name: 'screen four'


<ScreenFive@Screen>:
    name: 'screen five'


<PreScreenManager>:
    swiper_manager: swiper_manager  # uses the id from below

    MySwiperManager:
        orientation: 'vertical'

        MDSwiperManager:
            id: swiper_manager

            ScreenOne:

            ScreenTwo:

            ScreenThree:

            ScreenFour:

            ScreenFive:

主电压（千伏）

AnchorLayout:
    canvas.before:
        Rectangle:
            size: self.size
            pos: self.pos
            source: "Start/Background.png"   
    anchor_x: 'center'
    anchor_y: 'top'
    Image:
        source: 'Start/Loginlogo.png'
        keep_ratio: False
        allow_stretch: True
        opacity: 1
        size_hint: 1, 0.25
        pos_hint: (0,0)  
    ScreenManager:
        id: screen_manager
        PreScreenManager:
            id: PreScreenManager

AnchorLayout:
    canvas.before:
        Rectangle:
            size: self.size
            pos: self.pos
            source: "Start/Background.png"   
    anchor_x: 'center'
    anchor_y: 'top'
    Image:
        source: 'Start/Loginlogo.png'
        keep_ratio: False
        allow_stretch: True
        opacity: 1
        size_hint: 1, 0.25
        pos_hint: (0,0)  
    ScreenManager:
        id: screen_manager
        PreScreenManager:
            id: PreScreenManager

您将类定义（

MySwiperManager

）与类的实例（例如

MySwiperManager（）

）混淆。通常，您的所有代码都应该在实例级别，将内容放在类级别通常是错误的，但这是一个常见的错误

---

不可能给出具体的解决方案，因为您的示例并不完整（事实上，它还存在一些其他问题，始终提供一个最小的可运行示例以使事情更简单），但是一般的答案是，您希望访问

MySwiperManager

类的一个实例的

ids

属性。

我想我几乎理解了您的意图。要在

PreScreenManager

中自动设置

swiper\u管理器

，请首先将属性添加到

PreScreenManager.kv

文件中：

<PreScreenManager>:
    swiper_manager: swiper_manager  # uses the id from below
    my_sm: msm  # uses the id from below

    MySwiperManager:
        orientation: 'vertical'
        id: msm

        MDSwiperManager:
            id: swiper_manager

            ScreenOne:

            ScreenTwo:

            ScreenThree:

            ScreenFour:

            ScreenFive:

我从未使用过

kivyMD

，因此我无法保证

do\u setup（）

方法中的代码的正确性。最后，通过修改

MainApp

类，计划执行

do\u setup（）

方法：

class PreScreenManager(Screen):
    swiper_manager = ObjectProperty()  # reference to MDSwiperManager from kv file
    my_sm: ObjectProperty()  # reference to MySwiperManager from kv file

    def do_setup(self, dt):
        # code to do the setup (called after App is instantiated)
        theme_cls = ThemeManager()
        theme_cls.primary_palette = 'Indigo'
        paginator = MDSwiperPagination()
        paginator.screens = self.swiper_manager.screen_names
        paginator.manager = self.swiper_manager
        self.swiper_manager.paginator = paginator
        self.my_sm.add_widget(paginator)

class MainApp(App):
    def build(self):
        # create an instance of PreScreenManager
        psm = PreScreenManager()

        # schedule the execution of the do_setup() method
        Clock.schedule_once(psm.do_setup)

        # return the PreScreenManager instance as the root of the App display
        return psm

---

谢谢你的评论。我只是添加了它所缺少的.py和.kv文件，使之成为一个可运行的示例。是的，这就是我正在尝试做的，谢谢。当我运行您编写的代码时，我得到了

AttributeError:'MainApp'对象没有属性'theme\u cls'

，因此我添加了

theme\u cls=ThemeManager（）theme_cls.primary_palette='Indigo'

到

MainApp

但是现在我得到了

paginator.screens=self.swiper\u manager.screen\u names AttributeError:'NoneType'对象没有属性'screen\u names'

，这个错误表明没有设置

swiper\u manager

。仔细看看我的答案，确保你正确地实施了我的建议。而且，是的，将

主题_cls

移到

MainApp

中。是的，我丢失了对.kv文件的导入（我重新修改了该文件以测试它是否能正常工作），但知道错误消息是“AttributeError:“MySwiperManager”对象没有属性“screen\u names”。我想我现在可能已经解决了它。我知道了以后会回信的。也许

swiper\u manager:msm#使用下面的id

应该是

swiper\u manager:swiper\u manager#使用下面的id

。