如何从另一个屏幕获取字段值？

Question

我在 TokenScreen 中有一个字段，我在 ListScreen 中有一个 MDList。问题是，我找不到从 TokenScreen 中的字段获取值并将其传递给 ListScreen 类的方法，以便用小部件填充容器。我尝试使用 init ，但这是不可能的。

它应该从 MDField 中获取文本值并将其传递给g = Github(TOKEN)

py 文件：

class passVarClass():
    def __init__(self):
        self.tokenPassVar = ""


class MainApp(MDApp):
    screen = Screen()

    def build(self):
        self.theme_cls.primary_palette = 'Blue'
        screen = Builder.load_file('layout.kv')
        return screen

    def set_screen(self, screen):
        self.root.current = screen
        print("switching screen to tokenscreen")


class TokenScreen(Screen):
    def on_pre_leave(self, *args):
        objectPass = passVarClass()

        objectPass.tokenPassVar = self.ids.tokenFieldID.text
        print(objectPass.tokenPassVar + "test_tokenClass")

    # pass


class ListScreen(Screen):
    def on_pre_enter(self, *args):

        objectPass = passVarClass()

        g = Github(objectPass.tokenPassVar)
        user = g.get_user()
        repos = user.get_repos()
        for x in repos:
            if x.language is not None:
                self.ids.container.add_widget(
                    TwoLineListItem(text=x.name, secondary_text=x.language)
                )

        pass


class RepoScreen(Screen):
    pass


sm = ScreenManager()
sm.add_widget(TokenScreen(name='tokenscreen'))
sm.add_widget(ListScreen(name='listscreen'))
sm.add_widget(RepoScreen(name='reposcreen'))

if __name__ == '__main__':
    MainApp().run()

kv 文件：

ScreenManager:
    id:scr_mngr
    TokenScreen:
    ListScreen:
    RepoScreen:

<TokenScreen>:
    id:tokenscreenID
    name:'tokenscreen'
    MDToolbar:
        id:toolbarID
        title:"TokenScreen"
        md_bg_color: app.theme_cls.primary_color
        elevation : 10
        left_action_items : [["arrow-left",lambda x: x]]
        pos_hint:{"top":1}
    MDTextFieldRound:
        id:tokenFieldID
        name:"tokenFieldName"
        hint_text:"token"
        mode:"rectangle"
        pos_hint: {'center_x':0.5,'center_y':0.6}
        size_hint_x:None
        width:250
    MDRectangleFlatButton:
        text:"test"
        pos_hint:{'center_x':0.5,'center_y':0.5}
        on_press: root.manager.current = 'listscreen'
        on_press:print("Switching to listscreen")
<ListScreen>:
    id:listScreenID
    name:'listscreen'
    BoxLayout:
        orientation: 'vertical'
    MDToolbar:
        id:toolbarID
        title:"ListScreen"
        md_bg_color: app.theme_cls.primary_color
        elevation : 10
        left_action_items : [["arrow-left",lambda x: app.set_screen("tokenscreen")]]
        pos_hint:{"top":1}
    ScrollView:
        y: -toolbarID.height
        MDList:
            id:container
<RepoScreen>:
    id:repoScreenID
    name:'reposcreen'

Answer 1

您必须定义一个属性。首先阅读此来源：

https://kivy.org/doc/stable/api-kivy.properties.html

这是一个简单的属性定义示例：

.kv

Manager:
    mgr: sc_mgr
    Main:
        id: sc_mgr
    About:

<MyPaintWidget>:
    on_touch_down: self.on_touch_down
    on_touch_move: self.on_touch_move

<Main>:
    name: "main"
    draw: main_draw
    BoxLayout:
        orientation: "vertical"

        MyPaintWidget:
            id: main_draw
            size_hint: 1, 0.9

        GridLayout:
            size_hint: 1, 0.1
            cols: 3
            padding: 10

            Button:
                text: "About"
                on_press:
                    root.manager.current= "about"
                    root.manager.transition.direction= "left"
            Label:
            
            Button:
                text: "Clear"
                on_release: app.root.cleaner()

<About>:
    name: "about"
    BoxLayout:
        orientation: "vertical"
        padding: 10

        Label:
            size_hint: 1, 0.9
            text: "This is a test app."

        Button:
            size_hint: 1, 0.9
            text:"Back to Main"
            on_press:
                root.manager.current= "main"
                root.manager.transition.direction= "right"

.py

from random import random
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.graphics import Ellipse, Color, Line
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
from kivy.properties import ObjectProperty

class Main(Screen):
    draw = ObjectProperty(None)

class About(Screen):
    pass

class Manager(ScreenManager):
    mgr = ObjectProperty(None)

    def cleaner(self):
        self.mgr.draw.clean()


class MyPaintWidget(Widget):

    def clean(self):
        self.canvas.clear()
    
    def on_touch_down(self, touch):
        # self.rect.pos = touch.pos
        color = (random(),random(),random())
        with self.canvas:
            Color(*color)
            Ellipse(pos=(touch.x, touch.y), size=(20,20))
            touch.ud['line'] = Line(points=(touch.x, touch.y))

    def on_touch_move(self, touch):
        # self.rect.pos = touch.pos
        touch.ud['line'].points += [touch.x, touch.y]
        

main_style = Builder.load_file("ms_paint.kv")

class MyPaintApp(App):
    def build(self):
        return main_style


if __name__ == '__main__':
    MyPaintApp().run()