kivy AttributeError: 'button' object has no attribute 'background_color'

Question

Actually, I was testing kivy, which is I just installed and I made a simple program to test it and here is the program:-

from kivy.app import App
from kivy.uix.widget import Widget

class button(Widget):
    pass

class ButtonApp(App):
    def build(self):
        return button()

if __name__=="__main__":
    ButtonApp().run()

When I run it, I got the following error. I tried to solve it and searched on the google too many times but not getting the solution. Please help me out.

 Traceback (most recent call last):
   File "/root/PycharmProjects/untitled/Button.py", line 12, in <module>
     ButtonApp().run()
   File "/root/kivyinstall/local/lib/python2.7/site-packages/kivy/app.py", line 802, in run
     root = self.build()
   File "/root/PycharmProjects/untitled/Button.py", line 9, in build
     return button()
   File "/root/kivyinstall/local/lib/python2.7/site-packages/kivy/uix/widget.py", line 345, in __init__
     Builder.apply(self, ignored_consts=self._kwargs_applied_init)
   File "/root/kivyinstall/local/lib/python2.7/site-packages/kivy/lang/builder.py", line 451, in apply
     self._apply_rule(widget, rule, rule, ignored_consts=ignored_consts)
   File "/root/kivyinstall/local/lib/python2.7/site-packages/kivy/lang/builder.py", line 506, in _apply_rule
     rule.canvas_root, rootrule)
   File "/root/kivyinstall/local/lib/python2.7/site-packages/kivy/lang/builder.py", line 831, in _build_canvas
     '{}: {}'.format(e.__class__.__name__, e), cause=tb)
 kivy.lang.builder.BuilderException: Parser: File "/root/kivyinstall/local/lib/python2.7/site-packages/kivy/data/style.kv", line 17:
 ...
      15:    canvas:
      16:        Color:
 >>   17:            rgba: self.background_color
      18:        BorderImage:
      19:            border: self.border
 ...
 BuilderException: Parser: File "/root/kivyinstall/local/lib/python2.7/site-packages/kivy/data/style.kv", line 17:
 ...
      15:    canvas:
      16:        Color:
 >>   17:            rgba: self.background_color
      18:        BorderImage:
      19:            border: self.border
 ...
 AttributeError: 'button' object has no attribute 'background_color'
   File "/root/kivyinstall/local/lib/python2.7/site-packages/kivy/lang/builder.py", line 249, in create_handler
     return eval(value, idmap), bound_list
   File "/root/kivyinstall/local/lib/python2.7/site-packages/kivy/data/style.kv", line 17, in <module>
     rgba: self.background_color
   File "kivy/weakproxy.pyx", line 30, in kivy.weakproxy.WeakProxy.__getattr__ (/tmp/pip-build-LU3E8I/kivy/kivy/weakproxy.c:1386)

   File "/root/kivyinstall/local/lib/python2.7/site-packages/kivy/lang/builder.py", line 825, in _build_canvas
     key, value, prule, idmap, True)
   File "/root/kivyinstall/local/lib/python2.7/site-packages/kivy/lang/builder.py", line 254, in create_handler
     cause=tb)


Process finished with exit code 1

Answer 1

There is already a Kivy widget called Button . Your own button class is conflicting with this, due to case differentiation limitations in kv language.

In general, you should CamelCase for widget class names (in line with pep8), and avoid replicating Kivy's built in class names. This will ensure that everything works correctly.