Python/Kivy passing variables

Question

Struggling to pass a variable to kivy window. I have read similar threads all over the place but none of the fixes seem to work for me. Im sure this is simple to someone who knows their way around tiny, unfortunately I don't.

main.py

import kivy
from kivy.uix.togglebutton import ToggleButton
from kivy.app import App
from kivy.uix.gridlayout import GridLayout
from kivy.clock import Clock
from kivy.lang import Builder
from kivy.app import App
kivy.require('1.10.0')
from phue import Bridge
import nest
b = Bridge('xxx.xxx.x.xxx')
b.connect()
b.get_api()
lights = b.lights

class Controller(GridLayout):

    print("launching")


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

    def KitchenSpot1(self,state):
        lights[0].name
        lights[0].on = state

    def update(dt):
        if b.get_light(1, 'on')== True:
            #print("down") # When this line is commented out I get an continuous accurate update on the status of the light, showing that its working.
            return 'down' # This is the part I want passed to the state criteria in the ivy window
        else:
            #print("up")# When this line is commented out I get an continuous accurate update on the status of the light, showing that its working.
            return 'down' # This is the part I want passed to the state criteria in the ivy window



class ActionApp(App):

    def build(self):

        Clock.schedule_interval(Controller.update, 1.0 / 60.0)
        return Controller()

myApp = ActionApp()
myApp.run()

action.kv

<Controller>:
    cols: 4
    rows: 3
    spacing: 10

    ToggleButton:
        id: KitchenSpot1Toggle
        text: "Kitchen Spot 1"
        on_press: root.KitchenSpot1(True) 

        #on_release: root.KitchenSpot1(False)
        #state1 = app.update.h
        state: Controller.update # This is the part that is throwing up the error.

The error:

      11:        #on_release: root.KitchenSpot1(False)
      12:        #state1 = app.update.h
 >>   13:        state: Controller.update
      14:
      15:
...
 NameError: name 'Controller' is not defined

Thanks in advance to anyone that can help me.

Answer 1

Make update an instance method and use a StringProperty to update state property in your kv:

main.py:

import kivy
kivy.require('1.10.0')
from kivy.app import App
from kivy.clock import Clock
from kivy.lang import Builder
from kivy.properties import StringProperty
from kivy.uix.gridlayout import GridLayout
from kivy.uix.togglebutton import ToggleButton
from phue import Bridge
import nest



b = Bridge('xxx.xxx.x.xxx')
b.connect()
b.get_api()
lights = b.lights


class Controller(GridLayout):
    state = StringProperty('normal')                        # <<<<<<<<<<<<

    def __init__(self, **kwargs):
        super(Controller, self).__init__(**kwargs)
        Clock.schedule_interval(self.update, 1.0 / 60.0)

    def KitchenSpot1(self,state):
        lights[0].name
        lights[0].on = state

    def update(self, dt):
        if b.get_light(1, 'on'):
            self.state = 'down'                           # <<<<<<<<<<<<
        else:
            self.state = 'normal'                         # <<<<<<<<<<<<


class ActionApp(App):
    def build(self):
        return Controller()


if __name__ == "__main__":
    myApp = ActionApp()
    myApp.run()

action.kv:

<Controller>:
    cols: 4
    rows: 3
    spacing: 10
    state: "normal"                                      # <<<<<<<<<<<<

    ToggleButton:
        id: KitchenSpot1Toggle
        text: "Kitchen Spot 1"
        on_press: root.KitchenSpot1(True)

        #on_release: root.KitchenSpot1(False)
        #state1 = app.update.h
        state: root.state                                # <<<<<<<<<<<<

Answer 2

Here is a more generic simplified answer from the kivy documentation , look for the section called "Keyword arguments and init ()" because there are some other ways to do it as well.

The following code passes myvar to the build() method of MyApp. It does this by over-riding the init () of the Kivy App class by a new init () that calls App. init () and then continues with whatever extra initialisation you want. You can then store variables in the MyApp class instances and use them in build().

from kivy.app import App
from kivy.uix.label import Label

myvar = 'Hello Kivy'

class MyApp(App):

    def __init__(self, myvar, **kwargs):
        super(MyApp, self).__init__(**kwargs)
        self.myvar = myvar

    def build(self):
        widget = Label(text=self.myvar)
        return widget

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