Kivy Dynamic Classes - Second Screen not Linked

Question

I am trying to use the Dynamic Classes technique to format my code nicer, rather than have everything in one .kv file. I look over this answer and tried to replicate it as best as I could to what I have, but am running into an issue.

The code works, but does not transition to the "select" screen once the password is entered correctly. Instead, the input text is cleared (as it should be), though does not transition. Almost as if the "select" screen is not properly linked. I am not sure where I am going wrong. Could someone provide me with some assistance?

main.py

from kivy.app import App
from kivy.lang.builder import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.popup import Popup
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout


def invalid_login():
    app = App.get_running_app()
    app.root.current = "Main"
    # Create a BoxLayout to add multiple lines or buttons to a PopUp
    box = BoxLayout()
    # Create PopUp
    pop = Popup(
        title="Invalid Password",
        size_hint=(None, None), size=(200, 100),
        content=box,
        auto_dismiss=False
    )
    # Dismiss PopUp
    box.add_widget(Button(text="Close", on_release=pop.dismiss))
    pop.open()


class MainWindow(Screen):
    def login(self):
        if self.ids.password.text == "Password":
            # Clear TextInput
            self.ids.password.text = ""
            # Go to the next page
            app = App.get_running_app()
            app.root.current = "Select"
        else:
            self.ids.password.text = ""
            invalid_login()


class SelectWindow(Screen):
    pass


class TrainingWindow(Screen):
    pass


class ModelWindow(Screen):
    pass


class TrainModelWindow(Screen):
    pass


class ParametersWindow(Screen):
    pass


class WindowManager(ScreenManager):
    pass


kv_main = Builder.load_file('main.kv')
kv_select = Builder.load_file('select.kv')
kv_training = Builder.load_file('training.kv')
kv_model = Builder.load_file('model.kv')
kv_train_model = Builder.load_file('train_model.kv')
kv_parameters = Builder.load_file('parameters.kv')

class MyApp(App):
    def build(self):
        return kv_main


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

main.kv

#:import utils kivy.utils
#:include main.kv
#:include select.kv
#:include training.kv
#:include model.kv
#:include train_model.kv
#:include parameters.kv

MainWindow:
    name: "Main"

    GridLayout:
        cols: 1

        BoxLayout:
            orientation: "vertical"
            canvas.before:
                Color:
                    rgba: 0,0,0,1
                Rectangle:
                    pos: self.pos
                    size: self.size
            Label:
                size_hint: 1, 1
                text: "App"
                font_size: 50
                color:
                    utils.get_color_from_hex('#FF0000')
            Label:
                size_hint: 1, 1
                text: "This App Does...."
                font_size: 40

        BoxLayout:
            size_hint: 1, 0.005
            canvas.before:
                Color:
                    rgba: (1,1,1,1)
                Rectangle:
                    size: self.size
                    pos: self.pos

        BoxLayout:
            orientation: "horizontal"
            size_hint: (0.35, 0.35)
            padding: (0,0,25,0)

            Label:
                font_size: 20
                text: "Password"
                size_hint: (0.5, 0.35)
                pos_hint: {'x': 1, 'y': 0.4}
                background_color: (0,0,0,1)
                canvas.before:
                    Color:
                        rgba: self.background_color
                    Rectangle:
                        size: self.size
                        pos: self.pos


            TextInput:
                id: password
                multiline: False
                size_hint: (0.5, 0.35)
                pos_hint: {'x': 1, 'y': 0.4}
                focus: True
                background_color:
                    utils.get_color_from_hex('#18B8D9')
                cursor_color: (0,0,0,1)
                password: True


        Button:
            text: "Submit"
            on_release: root.login()

select.kv

<SelectWindow@Screen>:
    name: "Select"

    BoxLayout:
        orientation: "vertical"
        Button:
            text: "Go Back"
            on_release:
                app.root.current = "Main"
                root.manager.transition.direction = "right"

`app.root.current = "Select"` <- it looks like you think app.root is a ScreenManager, but I think it's actually a Screen. Have you set up the widgets wrong? — inclement, Apr 13 '21 at 21:22
Yeah that was the problem. Thanks for pointing that out! I added the `WindowManager` to the `main.kv` file along with the necessary screens. — Binx, Apr 13 '21 at 22:18

score 0 · Accepted Answer · answered Apr 14 '21 at 15:24

As @inclement commented, I was trying to use a Screen as my ScreenManager. I updated my main.kv to the following and everything worked out.

WindowManager:
    MainWindow:
    SelectWindow:
    TrainingWindow:
    ModelWindow:
    TrainModelWindow:
    ParametersWindow:

<MainWindow>
    name: "Main"

Kivy Dynamic Classes - Second Screen not Linked

1 Answers1