title: Problem adding an MDExpansionPanel in a RecycleView Python/Kivy
body: <p><em>I'm not able to add an <code>MDExpansionPanel</code>  object in the RecycleView's data variable</em></p>
  <p><strong>main.py:</strong></p>
  <pre><code>from kivy.lang import Builder
  from kivy.uix.recycleview import RecycleView
  from kivymd.app import MDApp
  from kivymd.uix.expansionpanel import MDExpansionPanelOneLine
  
  Builder.load_string(&quot;&quot;&quot;
  &lt;MyRecycleView&gt;:
      viewclass: &quot;MDExpansionPanel&quot;
      effect_cls: &quot;ScrollEffect&quot;
      RecycleBoxLayout:
          default_size: None, dp(56)
          default_size_hint: 1, None
          size_hint_y: None
          height: self.minimum_height
          orientation: 'vertical'
          spacing: dp(10)
  &quot;&quot;&quot;)
  
  class MyRecycleView(RecycleView):
      pass
  
  class MyApp(MDApp):
      def build(self):
          recycle = MyRecycleView()
          recycle.data = [
              {
                  &quot;content&quot;:None,
                  &quot;icon&quot;:&quot;arrow-right&quot;,
                  &quot;panel_cls&quot;:MDExpansionPanelOneLine(
                      text=&quot;Test&quot;
                  )
              }
          ]
          return recycle
  
  MyApp().run()
  </code></pre>
  <p><strong>This returns an error:</strong></p>
  <pre><code>ValueError: KivyMD: `panel_cls` object must be must be one of the objects from the list
   [MDExpansionPanelOneLine, MDExpansionPanelTwoLine, MDExpansionPanelThreeLine]
  </code></pre>
  <p><em>I tried another way by creating a custom <code>MDExpansionPanel</code>  that already has the <code>MDExpansionPanelOneLine</code>  in the <code>panel_cls</code>  attribute and setting a property text to put in the text attribute of  <code>MDExpansionPanelOneLine</code></em></p>
  <p><strong>main.py</strong></p>
  <pre><code>from kivy.lang import Builder
  from kivy.uix.recycleview import RecycleView
  from kivymd.app import MDApp
  from kivymd.uix.expansionpanel import MDExpansionPanel
  from kivy.properties import StringProperty
  
  Builder.load_string(&quot;&quot;&quot;
  #:import MDExpansionPanelOneLine kivymd.uix.expansionpanel.MDExpansionPanelOneLine
  
  &lt;MyRecycleView&gt;:
      viewclass: &quot;MyExpansionPanel&quot;
      effect_cls: &quot;ScrollEffect&quot;
      RecycleBoxLayout:
          default_size: None, dp(56)
          default_size_hint: 1, None
          size_hint_y: None
          height: self.minimum_height
          orientation: 'vertical'
          spacing: dp(10)
  
  &lt;MyExpansionPanel&gt;:
      content: None
      panel_cls:
          MDExpansionPanelOneLine(\
              text=root.text
          )
  &quot;&quot;&quot;)
  
  class MyRecycleView(RecycleView):
      pass
  
  class MyExpansionPanel(MDExpansionPanel):
      text = StringProperty()
  
  class MyApp(MDApp):
      def build(self):
          recycle = MyRecycleView()
          recycle.data = [
              {
                  &quot;icon&quot;:&quot;arrow-right&quot;,
                  &quot;text&quot;:&quot;Test&quot;
              }
          ]
          return recycle
  
  MyApp().run()
  
  </code></pre>
  <p><em>This works but the text attribute of <code>MDExpansionPanelOneLine</code> doesn't change, the <code>text</code> property on the <code>RecycleView</code> data variable doesn't work.</em></p>
  <p><strong>Any idea how I can set a  <code>text</code>  attribute of an object that is inside  <code>panel_cls</code>  in the  <code>RecycleView</code>  data variable?</strong></p>