Updating a label from another class

Question

I want to make an apps which when i press the button save in AddTask Class, the text which is in the text input will directly updated to the Label which is in the Details Class, but what i'm doing is not working there.. can anyone please help me with this?

    
    kivy#7
    
    
    from kivy.app import App
    from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
    from KivyCalendar import DatePicker
    from kivy.lang import Builder
    from kivy.uix.popup import Popup
    from kivy.properties import ObjectProperty
    from database import DataBase
    from database2 import DataBase2
    from kivy.uix.label import Label
    from kivy.core.window import Window
    Window.size = (300,600)
    from kivy.config import Config
    Config.set('graphics', 'resizable', '0')
    Config.set('graphics', 'width', '300')
    
    
    Builder.load_file('window.kv')
    
    
    class HalamanUtama(Screen):
        def submit (self):
            name = self.ids.TaskName.text
            self.ids.task_one.text = name
    
        def next(self):
            layout = self.ids['invoices']
            arr = db.get_data()
            for invoice in arr:
                lab1 = Label(text=invoice, size_hint_x=.35, halign='left')
                layout.add_widget(lab1)
    
    
    class AddTask(Screen):
        names = ObjectProperty(None)
        desc = ObjectProperty(None)
        deadline = ObjectProperty(None)
        reminder1 = ObjectProperty(None)
    
        def submit(self):
            if self.names.text != "" and self.desc.text != "" and self.deadline.text != "" and self.reminder1.text != "":
    
                db.add_task(self.names.text, self.desc.text, self.deadline.text, self.reminder1.text)
                self.reset()
                hu = HalamanUtama()
                return hu.next()
    
            else:
                invalidForm()
    
        def reset(self):
            self.names.text = ""
            self.desc.text = ""
            self.deadline.text = ""
            self.reminder1.text = ""
    
        def update_value(self, inst):
            """ Update textinput value on popup close """
            self.text = "%s-%s-%s" % tuple(self.cal.active_date)
            self.focus = False
            App.get_running_app().root.ids.deadline.text = self.text
    
        def show_calendar(self):
            datePicker.show_popup(1, .3)
    
    
    class DetailTask(Screen):
        def btn(self):
            shows = Delete()
    
            popupWindow = Popup(title="Delete Task", content=shows, separator_height=0, size_hint=(None, None),
                                size=(230, 230))
            popupWindow.open()
    
    
    class UncompletedExam(Screen):
        def next(self):
            layout = self.ids['idk']
            arr = db2.get_data()
            for Idk in arr:
                lab2 = Label(text=Idk, size_hint_x=.35, halign='left')
                layout.add_widget(lab2)
    
    class AddExam(Screen):
        namess = ObjectProperty(None)
        descc = ObjectProperty(None)
        deadlinee = ObjectProperty(None)
        reminder11 = ObjectProperty(None)
    
    
        def submit(self):
            if self.namess.text != "" and self.descc.text != "" and self.deadlinee.text != "" and self.reminder11.text != "":
    
                db2.add_exam(self.namess.text, self.descc.text, self.deadlinee.text, self.reminder11.text)
                self.reset()
                ue = UncompletedExam()
                return ue.next()
    
            else:
                invalidForm()
    
        def update_value(self, inst):
            """ Update textinput value on popup close """
            self.text = "%s-%s-%s" % tuple(self.cal.active_date)
            self.focus = False
            App.get_running_app().root.ids.deadlinee.text = self.text
    
        def show_calendar(self):
            datePicker.show_popup(1, .3)
    
        def reset(self):
            self.namess.text = ""
            self.descc.text = ""
            self.deadlinee.text = ""
            self.reminder11.text = ""
    
    class DetailExam(Screen):
        pass
    
    class WindowsManager(ScreenManager):
        pass
    
    
    class Delete(Screen):
        pass
    
    
    class ListYPP(App):
        def build(self):
            return WindowsManager()
    
        def vibrate(self, time):
            vibrator.vibrate(time=5)
    
        def pattern(self, pattern):
            vibrator.pattern([0, 0, 1, 2])
    
        def exists(self):
            return self._exists()
    
        def cancel(self):
            self._cancel()
    
            # private
    
        def _vibrate(self, **kwargs):
            raise NotImplementedError()
    
        def _pattern(self, **kwargs):
            raise NotImplementedError()
    
        def _exists(self, **kwargs):
            raise NotImplementedError()
    
        def _cancel(self, **kwargs):
            raise NotImplementedError()
    
    def invalidLogin():
        pop = Popup(title='Invalid Login',
                    content=Label(text='Invalid username or password.'),
                    size_hint=(None, None), size=(300, 300))
        pop.open()
    
    
    def invalidForm():
        pop = Popup(title='Invalid Form',
                    content=Label(text='Please fill in all inputs with valid information.', font_size= 14.7),
                    size_hint=(None, None), size=(300, 300))
    
        pop.open()
    
    db2 = DataBase2("examdetail.txt")
    db = DataBase("taskdetail.txt")
    
    if __name__ == "__main__":
        ListYPP().run()
    
    
    database#1
    
    import datetime
    from KivyCalendar import DatePicker
    from kivy.config import Config
    
    Config.set('graphics', 'resizable', '0')
    Config.set('graphics', 'width', '300')
    
    class DataBase:
        def __init__(self, filename):
            self.filename = filename
            self.taskdetails = None
            self.file = None
            self.load()
    
        def load(self):
            self.file = open(self.filename, "r")
            self.taskdetails = {}
    
            for line in self.file:
                taskname, desc, deadline, reminder1 = line.strip().split(";")
                self.taskdetails[taskname] = (desc, deadline, reminder1)
            self.file.close()
    
        def add_task(self, taskname, desc, deadline, reminder1):
            if taskname.strip() not in self.taskdetails:
                self.taskdetails[taskname.strip()] = (desc.strip(), deadline.strip(), reminder1.strip())
                self.save()
                return 1
            else:
                print("Task Name exists already")
                return -1
    
        def get_data(self):
            FullDetails = self.taskdetails
            return FullDetails
    
        def save(self):
            with open(self.filename, "w") as f:
                for detail in self.taskdetails:
                    f.write(detail + ";" + self.taskdetails[detail][0] + ";" + self.taskdetails[detail][1] + ";" + self.taskdetails[detail][2] + "\n")
    
        @staticmethod
        def get_date():
            return str(datetime.datetime.now()).split(" ")[0]
    
    
    database#2
    
    import datetime
    class DataBase2:
        def __init__(self, filename):
            self.filename = filename
            self.examdetails = None
            self.file = None
            self.load()
    
        def load(self):
            self.file = open(self.filename, "r")
            self.examdetails = {}
    
            for line in self.file:
                examname, descc, deadlinee, reminder11 = line.strip().split(";")
                self.examdetails[examname] = (descc, deadlinee, reminder11)
            self.file.close()
    
        def add_exam(self, examname, descc, deadlinee, reminder11):
            if examname.strip() not in self.examdetails:
                self.examdetails[examname.strip()] = (descc.strip(), deadlinee.strip(), reminder11.strip())
                self.save()
                return 1
            else:
                print("Exam Name exists already")
                return -1
    
        def get_data(self):
            FullDetails = self.examdetails
            return FullDetails
    
        def save(self):
            with open(self.filename, "w") as f:
                for detail in self.examdetails:
                    f.write(detail + ";" + self.examdetails[detail][0] + ";" + self.examdetails[detail][1] + ";" + self.examdetails[detail][2] + "\n")
    
        @staticmethod
        def get_date():
            return str(datetime.datetime.now()).split(" ")[0]
    
    windows.kv
    
    #:import FadeTransition kivy.uix.screenmanager.FadeTransition
    
    :
        transition: FadeTransition()
        HalamanUtama:
        AddTask:
        DetailTask:
        UncompletedExam:
        AddExam:
        DetailExam:
        Delete:
    
    :
        name : "halamanutama"
        invoices:invoices
    
        FloatLayout:
            Image:
                source: 'REVISI TASK.jpg'
                pos_hint:{'left':1, 'top':1}
                size_hint : 1,1
                allow_stretch : True
                keep_ratio : False
    
        GridLayout:
            id: invoices
            cols: 1
            #orientation: "horizontal"
            padding : 5, 5
            spacing: 10, 10
            #size: 100, 50
            size_hint: 1, 0.7
            pos_hint: {'center_x':0.5, 'center_y':0.440}
    
    
            Button:
                text: ""
                background_color: 0,0,0,0
                canvas.before:
                    Color:
                        rgba: 0,0,0,1
                    Line:
                        width: 1
                        rectangle: self.x, self.y, self.width, self.height
                color: 0,0,0,1
                text_size: self.size
                halign: 'center'
                valign: 'middle'
    
            Button:
                text: ""
                background_color: 0,0,0,0
                canvas.before:
                    Color:
                        rgba: 0,0,0,1
                    Line:
                        width: 1
                        rectangle: self.x, self.y, self.width, self.height
                color: 0,0,0,1
                text_size: self.size
                halign: 'center'
                valign: 'middle'
    
            Button:
                text: ""
                background_color: 0,0,0,0
                canvas.before:
                    Color:
                        rgba: 0,0,0,1
                    Line:
                        width: 1
                        rectangle: self.x, self.y, self.width, self.height
                color: 0,0,0,1
                text_size: self.size
                halign: 'center'
                valign: 'middle'
    
            Button:
                text: ""
                background_color: 0,0,0,0
                canvas.before:
                    Color:
                        rgba: 0,0,0,1
                    Line:
                        width: 1
                        rectangle: self.x, self.y, self.width, self.height
                color: 0,0,0,1
                text_size: self.size
                halign: 'center'

Answer 1

You can do it with PutExtra for intents

Answer 2

Note: This Example will prove useful if you can understand it and will be easy for you to solve your problem.

class textinput_screen(widget):
    def __init__(self, **kwargs):
        supper().__init__(**kwargs)

    def pull_text(self):
       self.text_input = self.ids.ID_text_input.text 
       

class labelupdate_screen(widget):
    text_input_update = StringProperty()
    def __init__(self, **kwargs):
        supper().__init__(**kwargs)
        self.text_input_update = textinput_screen.text_input

class theapp(App):
    def build(self):
        self.screenm = ScreenManager()

        self.screen = Screen(name = "text input screem")
        screen.add_widget(self.textinput_screen)

        self.screen = Screen(name = "label update screen")
        screen.add_widget(self.labelupdate_screen)


        self.screenm.add_widget(screen)
if __name__ = "__main__":
    theapp.run()

<textinput_screen>
    ####your widgets####
    TextInput:
        id: Id_text_input
        text_hint: 'text input .... or something'

<labelupdate_screen>
     ####ur widgets#####
     Label:
         Text: root.text_input_update

Note: There are many similar questions about this issue. The main reason for this problem is that many people rely too much on kivy-lang, a text_input(.text) or a label(.text) is considered as widget attribute, if you intend to modify it then re-use it in another widget or a screen then you have to pass it as a variable inside one class or between classes. In this case a textinput.text from a class was retrieved by id then was passed to another class as a stringproperty.