Kivy and android sharedpreferences

Question

I am looking for a method to store settings persistently on android device, from Kivy framework.

I found Kivy documentation, overall informative, vague in this particular area. It mentions three methods (sorry, dont have enough reputation to provide clicable links, relative paths to kivy.org provided, I'd be glad if someone could fix those links):

1. [Storage] ./docs/api-kivy.storage.html#module-kivy.storage
2. [Settings] ./docs/api-kivy.uix.settings.html
3. [Config] ./docs/api-kivy.config.html

In addition to those, I'm aware that I could store data in a file, via pickle or database, but I'd like to use specifically sharedpreferences, or at least any Android/Kivy specific persistent storage.

1. However, I was unable to find any comparison, or explanation how they are different, and how they are used. Could anyone shed some light, had used them already?

2. Actually, I'm 80% sure that neither of this method uses Android's shared preferences, thus I thought about using jnius (4), and to do that I've tried (methods 1,2/3?,4), based on simple hello world example:

   from kivy.app import App
   from kivy.uix.button import Button
   
   import jnius  
   from kivy.config import Config  
   from kivy.storage.dictstore import DictStore  
   
   class MyApp(App):
   
       def build(self):
   
           path = "DEFAULT"
           try:  
               path = Config.get('kivy', 'my_important_variable')  
               print "\t\t\t KIVY 1:", Config.get('kivy', 'my_important_variable')  
           except Exception as err:
               print ("KIVY, 1, error: {}".format(repr(err)))  
   
           try:
               store = DictStore("MY_SETTINGS")
               path = store.get("my_important_variable")
               print "\t\t\t KIVY 2:", path
           except KeyError as err:
               print ("KIVY, 2, error: {}".format(repr(err)))
   
           try:
               prefs_m = jnius.autoclass('android.preference.PreferenceManager')
               prefs = prefs_m.getSharedPreferences()
               path = prefs.getString("my_important_variable", None)
               print "\t\t\t KIVY 3:", path
           except jnius.jnius.JavaException as err:
               print ("KIVY, 3, error: {}".format(repr(err)))
   
           btn1 = Button(text=path)
           btn1.bind(on_press=app.callback) #
           return btn1
   
       def callback(self, instance):
           print('The button <%s> is being pressed, SAVING...' % instance.text)
   
           try:
               Config.set('kivy', 'my_important_variable', "my_value_1")
           except Exception as err:
               print ("KIVY, 4, error: {}".format(repr(err)))
   
           try:
               store = DictStore("MY_SETTINGS")
               store.put("MY_SETTINGS", my_important_variable="my_value_2")
           except Exception as err:
               print ("KIVY, 5, error: {}".format(repr(err)))
   
           try:
               prefs_c = jnius.autoclass('android.content.SharedPreferences')
               prefs_m = jnius.autoclass('android.preference.PreferenceManager')
               prefs = prefs_m.getSharedPreferences()
               prefs_e = prefs.Editor()
               prefs_e.putString("my_important_variable", "my_value_3")
               prefs_e.commit()
           except Exception as err:
               print ("KIVY, 6, error: {}".format(repr(err)))
   
           try:
               context = jnius.autoclass('android.content.Context')
               # do I actually get context or a class here?
               prefs = context.getPreferences(0).edit();
               prefs.putString("my_important_variable", "my_value_4")
               prefs.commit()
           except Exception as err:
               print ("KIVY, 7, error: {}".format(repr(err)))
   
   if __name__ == '__main__':
       app = MyApp()
       app.run()
   

and here are logcat's results

... each time app is launched 
I/python  ( 5973): KIVY, 1, error: No option 'my_important_variable' in section: 'kivy'
I/python  ( 5973): KIVY, 2, error: KeyError('my_important_variable',)
I/python  ( 5973): KIVY, 3, error: JavaException('Unable to find a None method!',)

... button pressed
I/python  ( 5973): The button <DEFAULT> is being pressed, SAVING...
I/python  ( 5973): KIVY, 6, error: JavaException('Unable to find a None method!',)
I/python  ( 5973): KIVY, 7, error: AttributeError("type object 'android.content.Context' has no attribute 'getPreferences'",)

Notice, that 4, 5 "error msg's" didn't get called, so in theory they should have worked, but second launch I get same errors. I've run out of ideas how to crack it.

Answer 1

Kivy.Config is used to store settings that relate to the instantiation of the App class. It is usually placed at the very top of your Python script before any other kivy module is imported. This method is not platform specific, but the default path to the config file changes depending on the platform.

from kivy.config import Config
desktop=Config.getint('kivy', 'desktop')
if desktop == 1:
    print "This app is being run on a desktop."

The DictStore is a storage class that stores a dictionary to disk. The filename argument specifies the name of the file where the dictionary is stored. When the get function is called, a Python dictionary is returned.

from kivy.app import App
from kivy.uix.button import Button
from kivy.storage.dictstore import DictStore

class TestApp(App):
    def build(self):
        try:
            store = DictStore(filename="MY_SETTINGS")
            dictionary = store.get("my_important_variable")
            print "\t\t\t KIVY 2: DictStore Succeeded",
        except KeyError as err:
            dictionary = {'name': 'None'}
            print ("KIVY, 2, error: {}".format(repr(err)))

        self.text = str(dictionary)
        btn1 = Button(text=self.text)
        btn1.bind(on_press=self.callback) #
        return btn1

    def callback(self, instance):
        print('The button <%s> is being pressed, SAVING...' % instance.text)
        try:
            store = DictStore(filename="MY_SETTINGS")
            store.put("my_important_variable", name="John")
        except Exception as err:
            print ("KIVY, 5, error: {}".format(repr(err)))



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

I will provide the code for accessing shared prefs below. If you are interested in learning more please read http://developer.android.com/guide/topics/data/data-storage.html and https://kivy.org/planet/2015/04/python-on%C2%A0android/

from kivy.app import App
from kivy.uix.button import Button

import jnius

class TestApp(App):
    def build(self):
        try:
            PythonActivity = jnius.autoclass('org.renpy.android.PythonActivity')
            activity = PythonActivity.mActivity
            cntxt = activity.getApplicationContext()
            prefs = cntxt.getSharedPreferences("MY_PREFS", cntxt.MODE_PRIVATE )
            print "KIVY ACQUIRED SHARED PREFS"
            myVar = prefs.getString("my_important_variable", "Default String")
            print "\tKIVY 3: Retrieved SharedPref"
        except jnius.jnius.JavaException as err:
            myVar="Error Loading Prefs."
            print ("KIVY, 3, error: {}".format(repr(err)))

        self.text = myVar
        btn1 = Button(text=self.text)
        btn1.bind(on_press=self.callback) #
        return btn1

    def callback(self, instance):
        print('The button <%s> is being pressed, SAVING...' % instance.text)
        try:
            PythonActivity = jnius.autoclass('org.renpy.android.PythonActivity')
            activity = PythonActivity.mActivity
            cntxt = activity.getApplicationContext()
            prefs = cntxt.getSharedPreferences("MY_PREFS", cntxt.MODE_PRIVATE)
            editor = prefs.edit()
            editor.putString("my_important_variable", "This is important!")
            editor.commit()
            print "\tKIVY: Added string <This is important!> to shared prefs."
        except Exception as err:
            print ("\tKIVY, 6, error: {}".format(repr(err)))

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