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我无法通过我在 for 循环中定义的按钮更改屏幕，它显示此错误： AttributeError: type object 'ScreenManager' has no attribute 'manager' 我想在 .py 文件中定义它，因为它必须在for 循环为每个项目创建一个按钮。您可以在下面找到代码。请协助

from kivymd.app import MDApp
from kivy.lang.builder import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.properties import ObjectProperty,StringProperty
from kivymd.uix.list import MDList,OneLineListItem,TwoLineListItem
from kivymd.uix.button import MDFlatButton
#from kivy.uix.scrollview import ScrollView
#import json
from kivy.storage.jsonstore import JsonStore
from kivy.clock import Clock,mainthread
import sys
import os.path
import json

file = sys.argv[0]
foldername =os.path.dirname(file)

store = JsonStore(foldername+"/data.json")

screen_helper = """
ScreenManager:

    MainScreen: 
    AddScreen: 
    PerScreen: 
    TripDetail:

<MainScreen>:
    name:  'Main'
    MDRectangleFlatButton:
        text: 'add new'
        pos_hint: {'center_x':0.5,'center_y':0.5}
        on_press: root.manager.current = 'Add'
    MDRectangleFlatButton:
        text: 'pervius cal'
        pos_hint: {'center_x':0.5,'center_y':0.2}
        on_press: root.manager.current = 'Per'
<AddScreen>:
    id: addScreen
    name: 'Add'
    MDLabel:
        text: 'add new'
        halign: 'center'
        pos_hint:{'center_x':0.5,'center_y':0.9}
    MDRectangleFlatButton:
        text: 'back'
        pos_hint:{'center_x':0.5,'center_y':0.1}
        on_press: root.manager.current = 'Main'
    MDTextField:
        id: addNewCal
        hint_text: "Enter cal name:"
        pos_hint: {'center_x': 0.5,'center_y':0.6}
        size_hint_x: None
        width:300
    MDRectangleFlatButton:
        text: 'save'
        pos_hint:{'center_x':0.5,'center_y':0.4}
        on_press: root.save()
<PerScreen>:
    name: 'Per'
    ScrollView:
        size_hint_y:None
        height: 400
        MDList:
            id: tripList
    MDLabel:
        text: 'pervius cal'
        halign: 'center'
        pos_hint: {'center_x': 0.3,'center_y':0.9}
    MDRectangleFlatButton:
        text: 'back'
        pos_hint: {'center_x': 0.7,'center_y':0.9}
        on_press: root.manager.current = 'Main'
<TripDetail>:
    name: 'TripDetail'
    MDLabel:
        text: 'test'
"""

class MainScreen(Screen):
    pass

class AddScreen(Screen):
    screenManager = ObjectProperty(None)
    def save(self):
        calName = self.ids.addNewCal.text
        trip = {"tripname":calName,"persons":[],"sumCost": "0","personCost":[]}
        with open(foldername+"/data.json","r") as f:
            data = json.load(f)
            data["trips"].append(trip)
        with open(foldername+"/data.json","w") as f:
            json.dump(data,f,indent = 2)
        print(calName)

    pass

class PerScreen(Screen):
    
    @mainthread

    def on_enter(self, *args):
        """Event fired when the screen is displayed: the entering animation is
        complete."""
        
        def on_enter(interval):
            with open(foldername+"/data.json","r") as f:
                data = json.load(f)
                trip = data["trips"]
            self.ids.tripList.clear_widgets()
                
            **for i in range(len(trip)):
                self.ids.tripList.add_widget(MDFlatButton(text=trip[i]["tripname"],on_press = showTrip))
        def showTrip(self,*args):
            ScreenManager.manager.current = 'TripDetail'**
    
            

        Clock.schedule_once(on_enter)
class TripDetail(Screen):
    pass

sm = ScreenManager()
sm.add_widget(MainScreen(name='Main'))
sm.add_widget(AddScreen(name='Add'))
sm.add_widget(PerScreen(name='Per'))
sm.add_widget(TripDetail(name='TripDetail'))


class DongApp(MDApp):
    def build(self):
        screen = Builder.load_string(screen_helper)
        return screen  
        
    def showTrip(self):
        self.sm.current = 'TripDetail'


DongApp().run()
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1 回答 1

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错误消息告诉您您做错了什么。该类ScreenManager没有manager属性。您需要设置实例的current属性，该属性是ScreenManager从MDApp.

尝试改变：

ScreenManager.manager.current = 'TripDetail'

至：

MDApp.get_running_app().root.current = 'TripDetail'
于 2022-01-04T00:59:19.273 回答