How to switch screens in Kivy using the python code

Question

My code has the screenmanager and the App class in another python file. I want to cahnge the window from "order_screen" to "order_review" with the press of a button. I can achieve this affect in my kv code (See the second code)

class SubmitAll(Screen):
    Price = Price()
    new_list = []
    Order = Order_full()
    ordered_products =[]
    order = StringProperty(str(ordered_products))
    ReviewLayout = ReviewLayout()

    def __init__(self, **kwargs):
        Screen.__init__(self, **kwargs)
        b = Button(text="submit")
        b.bind(on_press=lambda x: self.submit_all())
#       b.bind(on_press=self.changer)
        self.add_widget(b)

    def submit_all(self):
        pass


    def changer(self,*args):
        self.manager.current = 'order_review'
        print('yes')

If I make the button in kv and use on_press: app.root.current it works flawlessly, however I cant achieve the same result in the python file.

<Order_Review@Screen>:
    name: "order_review"
    ReviewLayout:

<SubmitAll>:
    name: "submission"
    GridLayout:
        cols:1


        Button:
            text: "Submit All"
            on_press: root.submit_all()

            on_release:
                app.root.current = "order_review"

I tried using a changer method to make this happen, however I get the error

AttributeError: 'NoneType' object has no attribute 'current'

How can I replicate the same affect that I got in the kv code with app.root.current in my python code?(which is basiaclly switching screens with a button click)

------------edit Screen manager kv:

WindowManager:
    one: one

    MainWindow:
    Order_Page:
        id: one

    SubmitAll:
    Order_Review:

Screenmanager class:

class WindowManager(ScreenManager):
    def switching_function(*args):
        WindowManager.current = 'review'

The class is in another python file( the main one where eeverything else get imported)

Not enough information to determine what is happening. Are you using a `ScreenManager`? — John Anderson, Aug 09 '21 at 16:14

score 0 · Answer 1 · answered Aug 10 '21 at 02:36

0

Try changing the switching_function() to:

class WindowManager(ScreenManager):
    def switching_function(*args):
        self.current = 'order_review'

answered Aug 10 '21 at 02:36

John Anderson

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how would that help in any capacity, I need to switch the screen with a button press, I actually dont even use that method I could just type pass instead? – ChrisCross Aug 10 '21 at 16:28
Bind your `Button` to this method. – John Anderson Aug 10 '21 at 16:49
oh wow I moved it to my needed class instead of the window manager and it work with a bit of modifications! – ChrisCross Aug 10 '21 at 16:52

score 0 · Answer 2 · answered Aug 10 '21 at 16:55

adding this to my class


   def switching_function(self, *args):
        self.parent.parent.current = 'order_review'

and binding it to my button like


        self.b = Button(text= 'button')
        self.b.bind(on_press=lambda x: self.switching_function())
        self.add_widget(self.b)

worked perfectly but I am not sure what decides how many parent I need to use depending on the case.

How to switch screens in Kivy using the python code

2 Answers2