Kivy中ScreenManager跨屏提交TextInput值至ListView问题求助

嘿，我明白你遇到的问题了！你现在的核心困扰是跨屏幕访问其他Screen的控件属性——ProfileScreen里直接调用self.student_list肯定会报错，因为student_list是MainScreen独有的属性，ProfileScreen本身并没有这个东西。继承MainScreen虽然能拿到属性，但会连带继承界面元素，这显然不符合你的需求。

错误原因分析 #

你在ProfileScreen的okay方法里尝试用self.student_list，但self指的是当前ProfileScreen实例，它根本没有student_list这个属性，所以程序会抛出"ProfileScreen has no attribute 'student_list'"的错误。

解决方案：通过ScreenManager获取目标Screen实例 #

幸运的是，你已经在Manager类里定义了main_screen和profile_screen这两个ObjectProperty，并且在kv文件中正确绑定了对应的Screen实例。这意味着你可以通过self.manager拿到ScreenManager，再通过它获取MainScreen的实例，进而访问student_list。

修改ProfileScreen的okay方法即可：

def okay(self):
    abc_name = self.abc_text_input.text + " " + self.def_text_input.text
    # 通过ScreenManager获取MainScreen的实例
    main_screen_instance = self.manager.main_screen
    # 操作MainScreen里的ListView
    main_screen_instance.student_list.adapter.data.extend([abc_name])
    main_screen_instance.student_list._trigger_reset_populate()

修改后的完整Python代码 #

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import ObjectProperty
from kivy.uix.listview import ListItemButton
from kivy.uix.screenmanager import ScreenManager, Screen

class StudentListButton(ListItemButton):
    pass

class Manager(ScreenManager):
    main_screen = ObjectProperty()
    profile_screen = ObjectProperty()

class MainScreen(Screen):
    first_name_text_input= ObjectProperty()
    last_name_text_input= ObjectProperty()
    student_list = ObjectProperty()

    def submit_student(self):
        # Get the student name from the TextInputs
        student_name = self.first_name_text_input.text + " " + self.last_name_text_input.text
        # Add the student to the ListView
        self.student_list.adapter.data.extend([student_name])
        # Reset the ListView
        self.student_list._trigger_reset_populate()

    def delete_student(self, *args):
        if self.student_list.adapter.selection:
            # Get the text from the item selected
            selection = self.student_list.adapter.selection[0].text
            # Remove the matching item
            self.student_list.adapter.data.remove(selection)
            # Reset the ListView
            self.student_list._trigger_reset_populate()

    def replace_student(self, *args):
        # If a list item is selected
        if self.student_list.adapter.selection:
            # Get the text from the item selected
            selection = self.student_list.adapter.selection[0].text
            # Remove the matching item
            self.student_list.adapter.data.remove(selection)
            # Get the student name from the TextInputs
            student_name = self.first_name_text_input.text + " " + self.last_name_text_input.text
            # Add the updated data to the list
            self.student_list.adapter.data.extend([student_name])
            # Reset the ListView
            self.student_list._trigger_reset_populate()

class ProfileScreen(Screen):
    abc_text_input=ObjectProperty()
    def_text_input=ObjectProperty()

    def okay(self):
        abc_name = self.abc_text_input.text + " " + self.def_text_input.text
        # 获取MainScreen实例
        main_screen_instance = self.manager.main_screen
        # 添加到MainScreen的ListView
        main_screen_instance.student_list.adapter.data.extend([abc_name])
        # 重置ListView
        main_screen_instance.student_list._trigger_reset_populate()

class StudentDBApp(App):
    def build(self):
        return Manager()

if __name__=="__main__":
    StudentDBApp().run()

补充说明 #

• 这种方式的核心是利用ScreenManager作为中间层，管理所有Screen实例，这样任意一个Screen都可以通过self.manager访问到其他Screen的实例。
• 如果你没有在Manager里定义main_screen属性，也可以通过self.manager.get_screen("main_screen")来获取目标Screen（这里的"main_screen"是你在kv文件中给MainScreen设置的name属性），效果是一样的。比如：

  main_screen_instance = self.manager.get_screen("main_screen")
  

这样修改后，你点击ProfileScreen的"Okay"按钮就能正常把内容添加到MainScreen的ListView里，而且不会继承多余的界面元素啦！

内容的提问来源于stack exchange，提问作者Kadir Karadavut