c# - Dependency property value change call back is invoked when a control hides from UI via content control template - Stack Ove

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I have a content control with content control template which shows 2 controls in UI according to the content (as shown below).

I have DpValid dependency property in my usercontrol View1 & View2

<DataTemplate x:Key="MyT1Template">
     <local:View1 DpValid="{Binding Path=Data.DpValid, Source={StaticResource Proxy1}}"/>
</DataTemplate>

<DataTemplate x:Key="MyT2Template">
    <local:View2 DpValid="{Binding Path=Data.DpValid, Source={StaticResource Proxy1}}"/>
</DataTemplate>

<local:MyTemplateSelector x:Key="MyTemplateSelector"
                                    T1Template="{StaticResource MyT1Template}"
                                    T2Template="{StaticResource MyT2Template}" />

 <Grid>
     <ContentControl DockPanel.Dock="Top" 
                     Content="{Binding SelectedPropertyView}"
                     ContentTemplateSelector="{StaticResource MyTemplateSelector}">
         
     </ContentControl>
 </Grid>

In my View1, I am using a treeview to show some data. I have 2 template selectors which the treeview should use according to DpValid

 <local:DataItemTemplateSelector x:Key="DT1"
                                 ListTemplate="{StaticResource ListTemplate}"
                                 DefaultTemplate="{StaticResource DefaultTemplate}"/>

 <local:DataItemTemplateSelector x:Key="DT2"
                                 ListTemplate="{StaticResource ListTemplate}"
                                 DefaultTemplate="{StaticResource AnotherTemplate}" />

 public partial class View1: UserControl
 {
     public static readonly DependencyProperty DpValidProperty=
         DependencyProperty.Register(nameof(DpValid), typeof(bool), typeof(View1), new PropertyMetadata(true, OnChanged));

     public ListPropertiesView()
     {
         InitializeComponent();
     }

     public bool DpValid
     {
         get { return (bool)GetValue(DpValidProperty); }
         set { SetValue(DpValidProperty, value); }
     }

     private static void OnChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
     {
         if (d is View1 control)
         {
             control.UpdateTemplateSelector();
         }
     }

     private void UpdateTemplateSelector()
     {
         DataTemplateSelector ts = DpValid
             ? (DataTemplateSelector)Resources["DT1"]
             : (DataTemplateSelector)Resources["DT2"];
         treeview.ItemTemplateSelector = ts;
     }
 }

Its working. But I am getting some binding error when I switch from View1 to View2

HorizontalContentAlignment TreeViewItem.HorizontalContentAlignment HorizontalAlignment Cannot find source: RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1'.

But I am not setting these properties.

Another observation I made is that when the content control switches to View2, the Dependency Property value change is triggered with the default value, even though the bound property has not been modified.

It appears that during this value change, we attempt to set the ItemTemplateSelector, which leads to a binding error since the UI is now in View2.

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