Python 尝试将应用程序从Tkinter转换为Kivy:无法获取要更新的标签

我在Tkinter中有一个功能齐全的应用程序，我正试着了解Kivy是如何工作的，这几天我都遇到了麻烦。最后，我用.kv文件把一切都安排好了，完全放弃了。我认为，如果我能通过Python代码实现一些功能，那么我将开始理解Python和Kivy之间的关系。无论如何，现在的问题是，当我调用一个函数时，我无法更新标签。我现在只想得到一个标签，当我按下一个按钮时，它会改变文本。在特金特很容易，但在这里不是这样。我已经尝试了许多不同的组合，但我失败了。你会注意到这个按钮调用了tick函数，它最初是切换屏幕的，但是我改变了它，所以我可以让它改变标签。最终，我希望时钟能在屏幕顶部运行，但只需要让它更新为任意文本即可。一个完整的代码答复将是超级！ 另外，我意识到你们中的大多数人可能会在30分钟内完成整个应用程序，这是非常基本的

谢谢

这是我的密码：

import kivy
kivy.require('1.8.0')

from kivy.app import App
from kivy.uix.screenmanager import Screen, ScreenManager 
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.properties import ObjectProperty
from kivy.uix.image import Image
from kivy.event import EventDispatcher

import time
import datetime

class ScreenOne(Screen):

    def __init__ (self,**kwargs):
        super (ScreenOne, self).__init__(**kwargs)

        main_box = BoxLayout(orientation='vertical')
        header_box = BoxLayout(size_hint_y=None, height=35)
        top_box = BoxLayout(size_hint_y=None, height=60)
        middle_box = BoxLayout(size_hint_y=None, height=300)
        bottom_box = BoxLayout()
        middle1_box =BoxLayout(size_hint_x=None, width=50)
        middle2_box = BoxLayout(orientation='vertical')
        list_box1 = BoxLayout()
        list_box2 = BoxLayout()
        list_box3 = BoxLayout()
        list_box4 = BoxLayout()
        list_box5 = BoxLayout()
        list_box6 = BoxLayout()

        checkmark = 'Check_Mark.jpg'
        redX = Image(source='red_X')

        my_label1 = Label(text="BlaBlaBla on screen 1", font_size='24dp')
        my_button1 = Button(text="Go to screen 2",size_hint_y=None, size_y=100)
        my_button1.bind(on_press=self.tick)
        self.date_label = Label(text="not working")
        top_label = Label(text="The top text")
        mid_label = Label(text="The mid text")
        bot_label = Label(text="The bottom text")
        header_label = Label(text=" ")
        my_image = Image(source='colours.png', allow_stretch=True, keep_ratio=False)
        my_image2 = Image(source='colours2.png', allow_stretch=True, keep_ratio=False)

        my_image3 = Image(source='red_X.gif')

        fish_icon = Image(source=checkmark)
        coral_icon = Image(source=checkmark)
        topoff_icon = Image(source=checkmark)
        water_icon = Image(source=checkmark)
        filter_icon = Image(source=checkmark)
        bulb_icon = Image(source=checkmark)

        fish_label = Label(text="Last Fish Feeding", font_size=30)
        coral_label = Label(text="Last Coral Feeding", font_size=30)
        topoff_label = Label(text="Last water Top-Off", font_size=30)
        water_label = Label(text="Last Water Change", font_size=30)
        filter_label = Label(text="Last Filter Replacement", font_size=30)
        bulb_label = Label(text="Last Bulb Replacement", font_size=30)

        last_fish_date = Label(text="This is a date", font_size=30)
        last_coral_date = Label(text="This is a date", font_size=30)
        last_topoff_date = Label(text="This is a date", font_size=30)
        last_water_date = Label(text="This is a date", font_size=30)
        last_filter_date = Label(text="This is a date", font_size=30)
        last_bulb_date = Label(text="This is a date", font_size=30)

      #  main_box.add_widget(bot_label)
        main_box.add_widget(header_box)
        main_box.add_widget(top_box)
        main_box.add_widget(middle_box)
        main_box.add_widget(bottom_box)
        header_box.add_widget(header_label)
        header_box.add_widget(self.date_label)

        top_box.add_widget(my_image)
        middle_box.add_widget(middle1_box)
        middle1_box.add_widget(my_image3)
        middle_box.add_widget(middle2_box)
        middle2_box.add_widget(list_box1)
        middle2_box.add_widget(list_box2)
        middle2_box.add_widget(list_box3)
        middle2_box.add_widget(list_box4)
        middle2_box.add_widget(list_box5)
        middle2_box.add_widget(list_box6)

        list_box1.add_widget(fish_icon)
        list_box1.add_widget(fish_label)
        list_box1.add_widget(last_fish_date)
        list_box2.add_widget(coral_icon)
        list_box2.add_widget(coral_label)
        list_box2.add_widget(last_coral_date)
        list_box3.add_widget(topoff_icon)
        list_box3.add_widget(topoff_label)
        list_box3.add_widget(last_topoff_date)
        list_box4.add_widget(water_icon)
        list_box4.add_widget(water_label)
        list_box4.add_widget(last_water_date)
        list_box5.add_widget(filter_icon)
        list_box5.add_widget(filter_label)
        list_box5.add_widget(last_filter_date)
        list_box6.add_widget(bulb_icon)
        list_box6.add_widget(bulb_label)
        list_box6.add_widget(last_bulb_date)

        bottom_box.add_widget(my_button1)
        self.add_widget(main_box)
    def tick(self, *args):
        print ("test output")
        time1 = " "
        # get the current local time from the PC
        time2 = time.strftime('%H:%M:%S')
        time3 = time.strftime('%M:%S')

        date = datetime.datetime.strftime(date, "%m-%d-%Y   ")
        if time2 != time1:
            time1 = time2
            self.time1 = time1
            self.date_label(text=date + time2)




    def changer(self,*args):
        self.manager.current = 'screen2'

class ScreenTwo(Screen):

    def __init__(self,**kwargs):
        super (ScreenTwo,self).__init__(**kwargs)

        my_box1 = BoxLayout(orientation='vertical')
        my_label1 = Label(text="BlaBlaBla on screen 2",font_size='24dp')
        my_button1 = Button(text="Go to screen 1",size_hint_y=None, size_y=100)
        my_button1.bind(on_press=self.changer)
        my_box1.add_widget(my_label1)
        my_box1.add_widget(my_button1)
        self.add_widget(my_box1)

    def changer(self,*args):
        self.manager.current = 'screen1'

class TestApp(App):

        def build(self):
            my_screenmanager = ScreenManager()
            screen1 = ScreenOne(name='screen1')
            screen2 = ScreenTwo(name='screen2')
            my_screenmanager.add_widget(screen1)
            my_screenmanager.add_widget(screen2)
            return my_screenmanager

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

这一行导致崩溃，因为日期尚未定义，但您在其自己的定义中使用它

self.date_label(text=date + time2)

self.date_label是一个label实例，但不可调用。设置kivy属性的正确方法是将其作为属性访问：

self.date_label.text = time2

---

我删除了日期部分，因为它的定义中存在上述问题。

我删除了这篇文章的一些代码，定义一定是它的一部分。非常感谢。我可以在更改self.date_label.text后立即设置文本。我想这就是我现在需要继续的全部，因为我知道了更改Kivy属性的语法！因此，我立即尝试在不使用按钮的情况下调用此函数，并得到了未定义的错误。我在ScreenOne初始化类的最后一行添加了self.tick。我只想叫它一次。我想，即使在阅读了很多关于self的文章/博客之后，我也很难理解self。我现在尝试创建一个新函数，使用Kivy的时钟调度程序my_callbackdt:并计划了1秒的时间间隔来调用tickself、*args函数和get-fload对象没有属性日期标签。如果我注释掉新函数并使用按钮，一切仍然正常。

self.date_label(text=date + time2)