Kivy 在文本输入中访问文本的问题向程序添加屏幕和屏幕管理器

Question

在将其设为多屏应用程序之前没有任何问题，但现在我将其设为多屏应用程序时出现错误：

     if self.light_novel_list.adapter.selection:
 AttributeError: 'NoneType' object has no attribute 'adapter'

每当我在列表对象中选择一个项目时按下删除按钮。

当我收到 NoneType 错误时，我认为我以某种方式错误地引用了 kivy 层次结构中的对象，但我不确定如何。

我的相关代码是：

lightnovel.py:

import kivy
from urllib.request import Request, urlopen
from kivy.uix.screenmanager import ScreenManager, Screen
from bs4 import BeautifulSoup
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import ObjectProperty
from kivy.uix.listview import ListItemButton
from kivy.properties import StringProperty

class SavedListButton(ListItemButton):
    pass

class LightNovel(Screen):
    light_novel_text_input = ObjectProperty()
    light_novel_list = ObjectProperty()

    def delete(self):
        if self.light_novel_list.adapter.selection:

            selection = self.light_novel_list.adapter.selection[0].text
            self.light_novel_list.adapter.data.remove(selection)
            self.light_novel_list._trigger_reset_populate()

class Series(Screen):
    pass




class LightNovelApp(App):
    def build(self):
        screen_manager = ScreenManager()
        screen_manager.add_widget(LightNovel(name="screen_one"))
        screen_manager.add_widget(Series(name="screen_two"))
        return screen_manager

lnApp = LightNovelApp()
lnApp.run()

lightnovel.kv:

#: import main lightnovel
#: import ListAdapter kivy.adapters.listadapter.ListAdapter
#: import ListItemButton kivy.uix.listview.ListItemButton


<LightNovel>:
    BoxLayout:
        light_novel_text_input: searchbar
        light_novel_list: saved
        orientation: "vertical"
        id: main
        BoxLayout:
            id: secondbar
            size_hint: 1, .1
            Button:
                id: delete
                size_hint: .5, 1
                text: "Delete"
                on_press: root.delete()
            Button:
                id: goto
                size_hint: .5, 1
                text: "Go to"
                on_press: 
                    root.goto()
                    root.manager.transition.direction = 'left'
                    root.manager.transition.duration = 1
                    root.manager.current = 'screen_two'

        ListView:
            id: saved
            adapter:
                ListAdapter(data=["test"], cls=main.SavedListButton)

我删除了不必要的代码，以便更容易阅读，但我在其他函数中的所有 self. 引用也都失败了，这也是我认为我引用不正确的部分原因。

Answer 1

你的错误是你在boxlayout中定义了light_novel_text_input。

<LightNovel>:
    BoxLayout:
        light_novel_text_input: searchbar
        light_novel_list: saved

当你可能想要这个的时候，因为 ObjectPropertys 属于 LightNovel class:

<LightNovel>:
    light_novel_text_input: searchbar
    light_novel_list: saved
    BoxLayout:

Kivy 在文本输入中访问文本的问题向程序添加屏幕和屏幕管理器

Issue in Kivy accessing text in a text input adding screens and screen manager to the program

python

self

python-3.x

kivy

kivy-language