如何在 Kivy 中跨多个屏幕更新 Id 值

Question

I am currently attempting to create a password manager app using Kivy that generates and stores passwords for you. I came across an issue when attempting to save the current password that has been generated as when it goes to the next screen it resorts to using the very first id value not the updated value. I try to retrieve the value using the screen manager function get screen.

Any reason why this is and how to solve?

main.py:

class passwordCreator(Screen):

    def updatePassword(self): 
        current = self.ids.currentPassword
        current.text = self.generatePassword()


    def generatePassword(self):
        lower = string.ascii_lowercase
        upper = string.ascii_uppercase
        num = string.digits
        symbols = string.punctuation
        All = lower + upper + num + symbols 
        # Store all possible strings in one large string 

        temp = random.sample(All, random.randint(8,16))
        password = "".join(temp)

        return password
    
    def getPassword(self): 
        current = self.ids.currentPassword
        return current.text

    def save(self):
        password = self.getPassword()
        saves.append(password)
        print(saves)



class savingScreen(Screen):
    pass
    
class WindowManager(ScreenManager):
    pass


kv = Builder.load_file("my.kv")

class MyApp(App):

    def build(self):
        return kv


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

my.kv:

WindowManager:
    Menu:
    passwordCreator:
    savingScreen: 


<Menu>
    name: "menu"

    GridLayout:
        cols: 1 
        size: root.width, root.height
        
        Button:
            text:"Create Password"
            on_release: 
                app.root.current = "creatingPassword"

        Button:
            text: "Password List"


<passwordCreator>
    name: "creatingPassword"

    GridLayout:
        size: root.size
        rows: 3
        
        Label:
            id: currentPassword
            text: root.getPassword()

        Button:
            text: "Generate!"
            on_release:
                root.updatePassword()

        GridLayout: 
            cols: 3

            Button: 
                text: "Save"
                on_release:
                    app.root.current = "saving" 
            

            Button: 
                text: "Back" 
                on_release: 
                    app.root.current = "menu"

<savingScreen> 
    name: "saving" 

    GridLayout:
        size:root.size
        rows: 2 

        GridLayout:
            size:root.size 
            cols: 2

            Label: 
                text: root.manager.get_screen("creatingPassword").ids.currentPassword.text
            
            TextInput: 
                text: "What application is password for..."
                multiline: False
        
        Button:
            text: "SAVE"

Thanks for any help !

Answer 1

Setting the text of the Label using:

text: root.manager.get_screen("creatingPassword").ids.currentPassword.text

won't work only because kivy can't do the automatic binding for that expression. A way to get around that is to define a property in your savingScreen , and write your own code to update it:

class savingScreen(Screen):
    current_password = StringProperty('')

    def on_enter(self, *args):
        # update the curent_password property
        self.current_password = self.manager.get_screen('creatingPassword').ids.currentPassword.text

Then you can reference that property in the kv :

        Label: 
            # text: root.manager.get_screen("creatingPassword").ids.currentPassword.text
            text: root.current_password