object 没有属性（kivy）

Question

I am currently working on a mental health app and I have come to a problem in my code. In one of my classes called 'Controller', I have a slider widget and four buttons that are meant to direct to other pages. However, when I click on one, I am met with this error

File "kivy\weakproxy.pyx", line 32, in kivy.weakproxy.WeakProxy.__getattr__
AttributeError: 'Controller' object has no attribute 'Screen_One'

This is confusing me because from the coding in my class which will now show you:

class Controller(Screen):
def __init__(self):
    super(Controller, self).__init__()

def new_thickness(self, *args):
    self.lbl.text = str(int(args[1]))
    self.lbl.font_size = int(args[1]) * 6 + 10

def screen_one(self)
    self.reset() 
    sm.current = "Screen_One"

At first sight, it looks fine and I have been checking and I can't seem to find the problem with it. So I thought it could be the class for my Screen_One which I will now show you:

class Screen_One(Screen):
    text = ObjectProperty(None)

But as you can see there isn't much to present as it is all manufactured on my kivy or kv file and even that seems to be fine as I will present to you now:

This is the button that is meant to move to the page I need to go

Button:
    pos_hint: {"x": 0.0, "y": 11.5}
    text: 'Diary'
    background_color: 0, 0, 0, 1
    on_release:
        app.root.current = "Screen_One"
        root.manager.transition.direction = "right"
        root.Screen_One()

And the code for the page itself:

<Screen_One>:
name: 'screen_one'
text: text

FloatLayout

    Label:
        text: "You can express how you feel below :)"
        size_hint: 0.8, 0.2
        pos_hint: {"x":0.1, "top":1}
        font_size: (root.width**2 + root.height**2) / 14**4

    TextInput:
        id: text
        font_size: (root.width**2 + root.height**2) / 15**4
        multiline: False
        pos_hint: {"x": 0.5 , "top":0.8}
        size_hint: 0.4, 0.12

This projects needed for my grade which is due soon so could someone please help me?

Thank you:)

Answer 1

Change sm.current = Screen_One to sm.current = "screen_one" . You need to refer to the name of the screen, not the class name you've give it