UWP NavigationView Selected Item as CommandParameter in MVVM Community Toolkit

Question

UWP/XAML experts , How to set the selecteditem tag value as the CommandParameter in NavigationView SelectionChanged? Using community MVVM toolkit here. In example below the tag value is 3456 and would change dynamically .

CommandParameter="{Binding ????????}"

<muxc:NavigationView x:Name="DocumentNavView" Grid.Row="3" Grid.Column="0"
                  PaneDisplayMode="Left" 
                  IsTabStop="False" IsSettingsVisible="False" OpenPaneLength="200" Margin="10" 
                 IsBackButtonVisible="Collapsed" >
     <interactivity:Interaction.Behaviors>
         <core:EventTriggerBehavior EventName="SelectionChanged">
             <core:InvokeCommandAction Command="{x:Bind ViewModel.DocumentChanged}" CommandParameter="{Binding }" />
           
         </core:EventTriggerBehavior>
     </interactivity:Interaction.Behaviors>
    
    
         <muxc:NavigationViewItem   ToolTipService.ToolTip="Document1" Tag="3456">
             <muxc:NavigationViewItem.Content>
                 <StackPanel Orientation="Horizontal" >
                     <Image Source="ms-appx:///Assets/Doc.png" Width="20" Height="20" Margin="0 0 8 0" />
                     <TextBlock Text="Document1" Margin="8 0 0 0"></TextBlock>
                 </StackPanel>
             </muxc:NavigationViewItem.Content>
         </muxc:NavigationViewItem>
        
     </muxc:NavigationView.MenuItems>
     <Frame x:Name="rootFrame" >
     <Frame.ContentTransitions>
         <TransitionCollection>
             <NavigationThemeTransition/>
         </TransitionCollection>
     </Frame.ContentTransitions>
     </Frame>
 </muxc:NavigationView>

Answer 1

Hi @DotNET Fan ,

Welcome to Microsoft Q&A!

It is recommended to bind the NavigationView, then you can get the item in ViewModel.

 <core:InvokeCommandAction Command="{x:Bind ViewModel.DocumentChanged}"  CommandParameter="{Binding ElementName=DocumentNavView}" />

---

 public class TestViewModel
 {

     public ICommand DocumentChanged
     {
         get
         {
             return new CommadEventHandler<object>((s) => this.getContent(s));
         }

     }

     private void getContent(object obj)
     {
         try
         {
             Microsoft.UI.Xaml.Controls.NavigationView navigationView = (Microsoft.UI.Xaml.Controls.NavigationView)obj;
             Microsoft.UI.Xaml.Controls.NavigationViewItem item = navigationView.SelectedItem as Microsoft.UI.Xaml.Controls.NavigationViewItem;
             Debug.WriteLine(item.Tag);
         }
         catch (Exception ex)
         {
             Debug.WriteLine(ex.Message);
         }
     }
 }

Thank you.

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