Kivy not updating the label

Question

I think I have ready through all similar problems but cannot get this to work.

I am trying to update a label, defined in.kv file, via a python function. The label I am trying to update is lbl_autohours

I have tried StringProperty and like below, direct reference (self.ids.lbl_autohours.text = "test123"), and it works if I call it from a button click. But I want to call it from the.py-script once some data has been recieved. And I cannot get this to work.

...
# Welcome screen
class WelcomeScreen(Screen):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        Clock.schedule_once(self.updateInputField, 0.1)

    ... 

    def loadTimeseries(self, assetToShow, aspect):
        timeseries = get_timeseries(clientid, clientsecret, payload, assetToShow, aspect, latestValue="true")
        print("Done")
        mainApp.current = 'scr_177'
        screen_177.showData(timeseries)
...

class Screen_177(Screen):
    lbl_autohours = StringProperty()

    def __init__(self, **kwargs):
        super(Screen_177, self).__init__(**kwargs)
        self.lbl_autohours="123" #Works

    def showData(self, timeseries):
        print("Running showData")
        print(timeseries[0]['Auto_hours'])
        self.lbl_autohours = "test123" #Doesnt work 


...
mainApp = Builder.load_file("alogconn.kv")

# Main app 
class myApp(App):
    def build(self):
        return mainApp

# Run main program
if __name__ == "__main__":
    Window.clearcolor = (1, 1, 1, 1)
    screen_177 = Screen_177()
    my_app = myApp()
    my_app.run()
...

.KV file:

ScreenManagement: 
    id: screen_manager
    transition: WipeTransition(clearcolor=(1,1,1,1))
    welcomeScreen: scr_welcome
    loadingScreen: scr_loading
    screen177: scr_177
    WelcomeScreen:
        id: scr_welcome
    LoadingScreen:
        id: scr_loading
    Screen_177:
        id: scr_177
...
<Screen_177>:
    clearcolor: (1,1,1,1)
    name: 'scr_177'
    Image:
        source: 'logo.png'
        size_hint: 0.5, 0.5
        pos_hint: {"center_x":0.5, "top":1}
    Label:
        text: '177'
        font_size: 30
        size_hint: 1, 0.2
        pos_hint: {"center_x":0.5, "top":0.5}
    GridLayout:
        cols: 2
        id: data_grid
        Label:
            text: "Auto hours:"
        Label:
            id: lbl_autohours
            text: root.lbl_autohours
...

Answer 1

The way you referenced lbl_autohours is not really proper (I think) try this

# Welcome screen
class WelcomeScreen(Screen):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        Clock.schedule_once(self.updateInputField, 0.1)

    ... 

    def loadTimeseries(self, assetToShow, aspect):
        timeseries = get_timeseries(clientid, clientsecret, payload, assetToShow, aspect, latestValue="true")
        print("Done")
        mainApp.current = 'scr_177'
        self.parent.ids.screen_177.showData(timeseries)
...

class Screen_177(Screen):
    label_auto = StringProperty()
    def __init__(self, **kwargs):
        super(Screen_177, self).__init__(**kwargs)
        self.label_auto = "123"

    def showData(self, timeseries):
        print("Running showData")
        print(timeseries[0]['Auto_hours'])
        self.ids.lbl_autohours.text = "test123"


...
mainApp = Builder.load_file("alogconn.kv")

# Main app 
class myApp(App):
    def build(self):
        return mainApp

# Run main program
if __name__ == "__main__":
    Window.clearcolor = (1, 1, 1, 1)
    screen_177 = Screen_177()
    my_app = myApp()
    my_app.run()
...

and this

ScreenManagement: 
    id: screen_manager
    transition: WipeTransition(clearcolor=(1,1,1,1))
    welcomeScreen: scr_welcome
    loadingScreen: scr_loading
    screen177: scr_177
    WelcomeScreen:
        id: scr_welcome
    LoadingScreen:
        id: scr_loading
    Screen_177:
        id: scr_177
...
<Screen_177>:
    clearcolor: (1,1,1,1)
    name: 'scr_177'
    Image:
        source: 'logo.png'
        size_hint: 0.5, 0.5
        pos_hint: {"center_x":0.5, "top":1}
    Label:
        text: '177'
        font_size: 30
        size_hint: 1, 0.2
        pos_hint: {"center_x":0.5, "top":0.5}
    GridLayout:
        cols: 2
        id: data_grid
        Label:
            text: "Auto hours:"
        Label:
            id: lbl_autohours
            text: root.label_atuo

since lbl_autohours already exist in Screen_177 , why not refer to it with an ids and your code will be back to live and also be careful while naming ids and properties