我是 Kivy/KivyMD/programming 的新手，我只是沒有掌握 python 代碼和 kv 代碼之間的一些基本知識。我正在構建一個簡單的應用程序，它使用 ScreenManager 在兩個屏幕之間切換。在每個屏幕上，我計劃有一個動態生成的列表，其中包含來自數據庫的數據。我可以通過將它們放入 kv 文件來添加靜態列表和其他小部件。但我似乎無法理解如何在 python 文件的類中創建/更新數據并將其鏈接到 kv 文件 ID。在下面的代碼中，程序運行正常，我在其中放置了一個成功生成列表的按鈕，但目標是沒有按鈕并在應用程序啟動時自動生成列表。我已經對我嘗試過的事情添加了一些評論。我是在使用錯誤的變量名還是在做一些根本錯誤的事情？[main.py python 文件]from kivymd.app import MDAppfrom kivy.lang import Builderfrom kivy.uix.screenmanager import ScreenManager, Screenfrom kivymd.uix.list import OneLineListItemclass FirstWindow(Screen): print('This prints automatically when App launches') # But adding widgets doesn't happen automatically # I tried variations but the variable is always not defined #self.ids.list_one.add_widget(OneLineListItem(text='List Item 1')) #root.ids.list_one.add_widget(OneLineListItem(text='List Item 1')) #ids.list_one.add_widget(OneLineListItem(text='List Item 1')) # This function works when called from a button def button_push(self): for i in range (20): self.ids.list_one.add_widget(OneLineListItem(text=f'List Item {i}'))class SecondWindow(Screen): passclass WindowManager(ScreenManager): passclass MultiscreenApp(MDApp): def build(self): return Builder.load_file('Multiscreen.kv')if __name__ == '__main__': MultiscreenApp().run()[多屏.kv 文件]WindowManager: FirstWindow: name: 'firstwindow' SecondWindow: name: 'secondwindow'<FirstWindow>: BoxLayout: orientation: 'vertical' MDToolbar: title: 'SCREEN 1' Button: text: 'List maker button' on_release: root.button_push() ScrollView: MDList: id: list_one MDFloatingActionButton: elevation: 8 icon: 'plus' pos_hint: {'center_x': .5} on_press: app.root.current = 'secondwindow' root.manager.transition.direction = 'left'
2 回答
Smart貓小萌
TA貢獻1911條經驗 獲得超7個贊
您可以添加__init___方法來Clock.schedule_once觸發列表創建。修改后的代碼如下。我沒有更改其余代碼，只是添加了兩個函數來顯示自動列表創建。
from kivymd.app import MDApp
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivymd.uix.list import OneLineListItem
from kivy.clock import Clock
class FirstWindow(Screen):
print('This prints automatically when App launches')
def __init__(self, **kwargs):
super().__init__(**kwargs)
Clock.schedule_once(self.create_list)
def create_list(self, *args):
for i in range (20):
self.ids.list_one.add_widget(OneLineListItem(text=f'List Item {i}'))
# But adding widgets doesn't happen automatically
# I tried variations but the variable is always not defined
#self.ids.list_one.add_widget(OneLineListItem(text='List Item 1'))
#root.ids.list_one.add_widget(OneLineListItem(text='List Item 1'))
#ids.list_one.add_widget(OneLineListItem(text='List Item 1'))
# This function works when called from a button
def button_push(self):
for i in range (20):
self.ids.list_one.add_widget(OneLineListItem(text=f'List Item {i}'))
class SecondWindow(Screen):
pass
class WindowManager(ScreenManager):
pass
class MultiscreenApp(MDApp):
def build(self):
return Builder.load_file('Multiscreen.kv')
if __name__ == '__main__':
MultiscreenApp().run()
慕萊塢森
TA貢獻1810條經驗 獲得超4個贊
class FirstWindow(Screen):
def on_enter(self, *args):
"""Event fired when the screen is displayed: the entering animation is
complete."""
def on_enter(interval):
for i in range (20):
self.ids.list_one.add_widget(OneLineListItem(text=f'List Item {i}'))
Clock.schedule_once(on_enter)
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