从 Kivy 的另一个屏幕更改小部件

Question

我正在尝试通过 Kivy 另一个视图中的按钮更新一个小部件。

基维码：

<MainScreen>:
    relatorios : relatorios
    despesas : despesas
    GridLayout:
        size: root.width, root.height
        cols : 1
        Button:
            id: relatorios
            text: 'Relatorios'
            on_press: root.change_screen(rep = 'Report')
        Button:
            id: despesas
            text:  'Despesa'
            on_press: root.change_screen(rep = 'Expend')

<ReportScreen>:
    GridLayout:
        size: root.width, root.height
        cols : 1
        Button:
            id: semanal
            text: 'Semanal'
        Button:
            id: mensal
            text:  'Mensal'
        Button:
            id: anual
            text:  'Anual'
        Button:
            id: voltar
            text:  'Voltar'
            on_press: root.change_screen(rep = 'Main')

<ExpendScreen>:
    kind_selec1 : kind_select
    GridLayout:
        size: root.width, root.height
        cols : 2
        Label:
            id: kind
            text: 'Tipo de Despesa'
        Button:
            id: kind_select
            text:  'Selecionar'
            on_press: root.change_screen(rep = 'Kind')
        Label:
            id: way
            text:  'Meio de Pagamento'
        Button:
            id: selec_way
            text:  'Selecionar'
            on_press: root.change_screen(rep = 'Way')
        Label:
            id: parcelas
            text:  'Quantidade de Parcelas'
        TextInput:
            id: qtdy
        Label:
            id: value
            text:  'Valor Total'
        TextInput:
            id: qtdy
        Button:
            id: back
            text:  'Voltar'
            on_press: root.change_screen(rep = 'Main')
        Button:
            id: submit
            text:  'Registrar'
            on_press: root.change_name()

<DropDown1>:
    cols : 1
    orientation: 'vertical'

<DropDown2>:
    cols : 1
    orientation: 'vertical'

Python 代码：

from kivy.app import App
from kivy.uix.gridlayout import GridLayout
from kivy.uix.button import Button
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.label import Label
from kivy.uix.textinput import TextInput
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.widget import Widget
from functools import partial
from functions import Expense
from kivy.properties import ObjectProperty
import kivy
import time

class MainScreen(Widget):
    relatorios = ObjectProperty(None)
    despesas = ObjectProperty(None)

    def change_screen(self,rep):
        app_finan_con.screen_manager.current = rep
        return


class ReportScreen(Widget):
    def change_screen(self,rep):
        app_finan_con.screen_manager.current = rep
        return

class ExpendScreen(Widget):
    kind_selec1 = ObjectProperty()

    def __init__(self, **kwargs):
        super(ExpendScreen, self).__init__(**kwargs)
    def change_screen(self,rep):
        app_finan_con.screen_manager.current = rep
    def change_name(self):
        self.kind_selec1.text= 'porra'


class Dropdown1(BoxLayout):
    def __init__(self, **kwargs):
        super(Dropdown1, self).__init__(**kwargs)
        list = ['Alimentação', 'Transporte', 'Entretenimento','Moradia','Doação']
        for item in list:
            self.but = Button(text=item)
            self.add_widget(self.but)
            self.but.bind(on_release=partial(self.It,arg = item))

    def It(self,instance,arg):
        app_finan_con.screen_manager.current = 'Expend'
        ExpendScreen.change_name(ExpendScreen)


class Dropdown2(BoxLayout):
    def __init__(self, **kwargs):
        super(Dropdown2, self).__init__(**kwargs)
        list = ['Crédito', 'Débito', 'Dinheiro']
        for item in list:
            self.but = Button(text=item)
            self.add_widget(self.but)
            self.but.bind(on_release=partial(self.It, arg=item))

    def It(self,instance,arg):
        app_finan_con.screen_manager.current = 'Expend'



class MyApp(App):

    def build(self):
        self.screen_manager = ScreenManager()

        self.mainscreen = MainScreen()
        screen = Screen(name='Main')
        screen.add_widget(self.mainscreen)
        self.screen_manager.add_widget(screen)

        self.reportscreen = ReportScreen()
        screen = Screen(name='Report')
        screen.add_widget(self.reportscreen)
        self.screen_manager.add_widget(screen)

        self.expendscreen = ExpendScreen()
        screen = Screen(name='Expend')
        screen.add_widget(self.expendscreen)
        self.screen_manager.add_widget(screen)

        self.dropdown1 = Dropdown1()
        screen = Screen(name='Kind')
        screen.add_widget(self.dropdown1)
        self.screen_manager.add_widget(screen)

        self.dropdown2 = Dropdown2()
        screen = Screen(name='Way')
        screen.add_widget(self.dropdown2)
        self.screen_manager.add_widget(screen)

        return self.screen_manager

def change_screen():
    app_finan_con.screen_manager.current ='Report'
    return


if __name__ == '__main__':
    app_finan_con = MyApp()
    app_finan_con.run()

思路是使用screen Dropdown1通过这段代码修改screen ExpendScreen：

class Dropdown1(BoxLayout):
    def __init__(self, **kwargs):
        super(Dropdown1, self).__init__(**kwargs)
        list = ['Alimentação', 'Transporte', 'Entretenimento','Moradia','Doação']
        for item in list:
            self.but = Button(text=item)
            self.add_widget(self.but)
            self.but.bind(on_release=partial(self.It,arg = item)) (this line activates It method)

    def It(self,instance,arg):  
        app_finan_con.screen_manager.current = 'Expend'
        ExpendScreen.change_name(ExpendScreen) (this line activates method in ExpendScreen):

class ExpendScreen(Widget):
    kind_selec1 = ObjectProperty()

    def __init__(self, **kwargs):
        super(ExpendScreen, self).__init__(**kwargs)
    def change_screen(self,rep):
        app_finan_con.screen_manager.current = rep
    def change_name(self):
        self.kind_selec1.text= 'porra'

但我收到以下错误：AttributeError: 'kivy.properties.ObjectProperty' object has no attribute 'text'

但是当我从同一屏幕 (ExpendScreen) 中的按钮调用相同的方法时，它按预期工作，kivy 代码：

Button:
   id: submit
   text:  'Registrar'
   on_press: root.change_name()

图片示例：

谁能帮帮我？

Answer 1

你的代码行：

ExpendScreen.change_name(ExpendScreen) 

在没有实例的情况下调用ExpendScreen 的实例方法。那是行不通的。您需要获取属于您的 gui 的 ExpendScreen 的实例，并调用其 change_name 方法。我没有对此进行测试，但我认为将上面的行替换为：

app_finan_con.expendscreen.change_name()

会做你想做的。