dynamic binding of functions not working in kivy - python-3.x

Question

I wanted to make a dynamic class of a group of widget so whenever I add them to my main app, I had to only bring in the changes from somewhere(e.g. a python file, class etc, here I've done them in explicit lists), but binding the widget with properties like "on_text" which respond to events didn't really work, other properties like 'text', 'hint_text' worked perfectly but on_text doesn't really budge. I can't figure out the cause for this because I've checked the correct object being passed along the functions, below is my code:
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.properties import ObjectProperty
class Dynamic_TextInput(BoxLayout):
def __init__(self,changes=None, **kwargs):
super().__init__(**kwargs)
self.widgets = {'Mylabel':self.ids.mylabel,
'Myinput': self.ids.mytext}
self.Change(changes)
def Change(self, changes=None, **kwargs):
if changes:
for change in changes:
curwidget = self.widgets[change[0]]
cur_properties = change[1]
for attr in cur_properties.keys():
if attr=='bind':
print("The cur properties are: ")
print(cur_properties[attr])
curwidget.bind(**(cur_properties[attr]))
else:
setattr(curwidget, attr, cur_properties[attr])
class mainwidget(BoxLayout):
myobj1 = ObjectProperty()
myobj2 = ObjectProperty()
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.orientation='vertical'
change1=[('Mylabel', {'text':'firstchange',
'bind':{'on_text':lambda *_: print('something')}
}),
('Myinput', {'hint_text': 'Changed hint text'})
]
self.add_widget(Dynamic_TextInput(changes=change1))
self.add_widget(Dynamic_TextInput())
class MainApp(App):
def build(self):
return mainwidget()
if __name__ == '__main__':
MainApp().run()
And, in the kivy file:
#:kivy 1.10.0
<Dynamic_TextInput>:
myobj1: mylabel
myobj2: mytext
orientation: 'horizontal'
Label:
id: mylabel
text: 'testlable'
TextInput:
id: mytext
hint_text: 'some test'
What is the cause? And how can I fix it?

Answer 1

There are 2 ways to make a binding of a property:
*.py
object.bind(property=callback)
*.kv
object:
on_property: callback
So in the case of making the connection in python you should not use on_text, but text.
To verify the change, the Label can not be edited from the GUI, so I will use the TextInput to write on the Label:
*.py
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.properties import ObjectProperty
class Dynamic_TextInput(BoxLayout):
def __init__(self,changes=None, **kwargs):
super().__init__(**kwargs)
self.widgets = {'Mylabel':self.ids.mylabel,
'Myinput': self.ids.mytext}
self.Change(changes)
def Change(self, changes=None, **kwargs):
if changes:
for change in changes:
curwidget = self.widgets[change[0]]
cur_properties = change[1]
for attr in cur_properties.keys():
if attr=='bind':
print("The cur properties are: ")
curwidget.bind(**(cur_properties[attr]))
print(cur_properties[attr])
else:
setattr(curwidget, attr, cur_properties[attr])
class mainwidget(BoxLayout):
myobj1 = ObjectProperty()
myobj2 = ObjectProperty()
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.orientation='vertical'
change1=[('Mylabel', {'text':'firstchange',
'bind':{'text':lambda *_: print('something')}
}),
('Myinput', {'hint_text': 'Changed hint text'})
]
self.add_widget(Dynamic_TextInput(changes=change1))
self.add_widget(Dynamic_TextInput())
class MainApp(App):
def build(self):
return mainwidget()
if __name__ == '__main__':
MainApp().run()
*.kv
#:kivy 1.10.0
<Dynamic_TextInput>:
myobj1: mylabel
myobj2: mytext
orientation: 'horizontal'
Label:
id: mylabel
text: mytext.text # <----
TextInput:
id: mytext
hint_text: 'some test'