Python Kivy removing a label on the fly

[ev66]

Kivy and Python GUI

I can create a label programmatically, but am unable to remove the same label

If the label is already part of the GUI, I can remove it, but not a label I have created after app is running.

The error is:

File "C:\Users\evan\Desktop\Raspberry\v10.py", line 21, in removeMyLabel
self.remove_widget(self.ids.new_lb)
^^^^^^^^^^^^^^^

Can you help please ?
Thanks
pythoncode:

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.core.window import Window
from kivy.uix.button import Button
from kivy.uix.label import Label

# manually setting in script
Window.size = (800, 480)


class YourWidget(Widget):
    def __init__(self, **kwargs):
        super(YourWidget, self).__init__(**kwargs)
        pass

    def addMyLabel(self):
        new_lb = Label(text="X", size_hint=(None, None), size=(50, 50), pos=(50, 50))
        self.add_widget(new_lb)

    def removeMyLabel(self):
        self.remove_widget(self.ids.new_lb)


class V10App(App):
    def build(self):
        Window.clearcolor = (0.2, 0.2, 0.2, 1)
        return YourWidget()


if __name__ == "__main__":
    V10App().run()

kv code:

<YourWidget>:
    Button:
        id: button1
        text: 'Add The Label'
        pos: (100, 320)
        size: (450, 50)
        size_hint: (None, None)
        on_release: root.addMyLabel()

    Button:
        id: button2
        text: 'Remove The Label'
        pos: (100, 220)
        size: (450, 50)
        size_hint: (None, None)
        on_release: root.removeMyLabel()

 

[ratwolf]

Kivy and Python GUI

I can create a label programmatically, but am unable to remove the same label

If the label is already part of the GUI, I can remove it, but not a label I have created after app is running.

The error is:

Can you help please ?
Thanks
pythoncode:

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.core.window import Window
from kivy.uix.button import Button
from kivy.uix.label import Label

# manually setting in script
Window.size = (800, 480)


class YourWidget(Widget):
    def __init__(self, **kwargs):
        super(YourWidget, self).__init__(**kwargs)
        pass

    def addMyLabel(self):
        new_lb = Label(text="X", size_hint=(None, None), size=(50, 50), pos=(50, 50))
        self.add_widget(new_lb)

    def removeMyLabel(self):
        self.remove_widget(self.ids.new_lb)


class V10App(App):
    def build(self):
        Window.clearcolor = (0.2, 0.2, 0.2, 1)
        return YourWidget()


if __name__ == "__main__":
    V10App().run()

kv code:

<YourWidget>:
    Button:
        id: button1
        text: 'Add The Label'
        pos: (100, 320)
        size: (450, 50)
        size_hint: (None, None)
        on_release: root.addMyLabel()

    Button:
        id: button2
        text: 'Remove The Label'
        pos: (100, 220)
        size: (450, 50)
        size_hint: (None, None)
        on_release: root.removeMyLabel()

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.core.window import Window
from kivy.uix.button import Button
from kivy.uix.label import Label

# manually setting in script
Window.size = (800, 480)


class YourWidget(Widget):
    def __init__(self, **kwargs):
        super(YourWidget, self).__init__(**kwargs)
        self.my_label = None  # Keep reference to label

    def addMyLabel(self):
        if not self.my_label:
            self.my_label = Label(text="X", size_hint=(None, None), size=(50, 50), pos=(50, 50))
            self.add_widget(self.my_label)

    def removeMyLabel(self):
        if self.my_label:
            self.remove_widget(self.my_label)
            self.my_label = None


class V10App(App):
    def build(self):
        Window.clearcolor = (0.2, 0.2, 0.2, 1)
        return YourWidget()


if __name__ == "__main__":
    V10App().run()

I guess you're getting the error because self.ids.new_lb only works for widgets defined in the KV file with an id. However, the label you're trying to remove (new_lb) is created dynamically in Python, and it has no id in the ids dictionary.

Solution​

You need to keep a reference to the dynamically created label so you can remove it later.

 

[ev66]

Ok. That makes sense. The id is part of the kv file.
I think I have found a way, by using the widget,children reference.

However, your solution is much better, and works fine.

Thanks ratwolf.

 

[ratwolf]

Ok. That makes sense. The id is part of the kv file.
I think I have found a way, by using the widget,children reference.

However, your solution is much better, and works fine.

Thanks ratwolf.

o.k. good to hear that the solution works well