kivy button ID's within functions - button

Question

I am working on a fantasy football type app for a school project.
We have created a scrollview with a list of characters in a team within it, each assigned to a button. on press of the button a new scrollview displaying a second list of 'inactive character buttons' is displayed, allowing the user to press one to swap the first and second character from team to team.
our issue comes from a difficulty in managing to 'locate' which button is pressed in order to tell our swap function which two characters to swap on the list. Is it possible to retain the id of a button and call it into a new function on press of said button?
Our code is a bit messy, but is displayed bellow:
class SMApp(App):
teamlist = []
idvar = ""
btnlist = []
def popupfunc(self, event):
"""
creates a popup asking if the user wishes to swap a character from team to subs
then proceeds to allow user to choose who swaps
"""
def subscroll(self):
"""
opens scroll list of substitute characters in a popup
"""
sublist = []
curs.execute('SELECT * FROM Subs')
for row in curs:
sublist.append([row[0], row[2]])
layout = GridLayout(cols=2, spacing=10, size_hint_y=None)
layout.bind(minimum_height=layout.setter('height'))
for i in range(len(sublist)):
btn = Button(text=str(sublist[i][0]), size_hint_y=None, height=40)
layout.add_widget(btn)
lbl = Label(text=str(sublist[i][1]), size_hinty=None, height=40)
layout.add_widget(lbl)
root = ScrollView(size_hint=(None, None), size=(400, 400))
root.add_widget(layout)
popup2 = Popup(content=root, size=(7, 10), size_hint=(0.55, 0.8), title="list of subs")
popup2.open()
box = BoxLayout()
btn1 = Button(text='yeah ok')
btn2 = Button(text='nope')
popup1 = Popup(content=box, size=(10, 10), size_hint=(0.3, 0.3), title="add to team?")
btn2.bind(on_press=popup1.dismiss)
btn1.bind(on_press=subscroll)
box.add_widget(btn1)
box.add_widget(btn2)
popup1.open()
def build(self):
curs.execute('SELECT * FROM Team')
for row in curs:
self.teamlist.append([row[0], row[2]])
layout = GridLayout(cols=2, spacing=10, size_hint_y=None)
layout.bind(minimum_height=layout.setter('height'))
for i in range(len(self.teamlist)):
btn = Button(text=str(self.teamlist[i][0]), size_hint_y=None, height=40, id=str(i))
btn.bind(on_press=self.popupfunc)
self.btnlist.append(btn)
layout.add_widget(btn)
lbl = Label(text=str(self.teamlist[i][1]), size_hinty=None, height=40)
layout.add_widget(lbl)
for item in self.btnlist:
print item.id
root = ScrollView(size_hint=(None, None), size=(400, 400),
pos_hint={'center_x':.5, 'center_y':.5})
root.add_widget(layout)
return root
if __name__ == '__main__':
SMApp().run()

Answer 1

Each of the btn = Button(...) you create is a different object, therefore you can tell which is pressed. The thing is what way you'll choose.
You can use:
str(your button) and get a specific object address(?) like 0xAABBCCEE
bad, don't do that
Button(id='something', ...)
ids from kv language
or create own widget with a property for specific identificator. Then you'd use a loop for the parent's children which would check for identificator and do something:
for child in layout.children:
if child.id == 'something':
# do something
And it seems you'd need this loop inside your subscroll, or access that layout some other way.