In WinUI 3 ListView how to clear selection using MVVM

Question

 <ListView x:Name="UserRoles" ItemsSource="{x:Bind ViewModel.UserRoles, Mode=OneWay}"  
                                      SelectionMode="Multiple"  
                                      VerticalContentAlignment="Top"    
                                      ScrollViewer.IsVerticalRailEnabled="True"  
                                      ScrollViewer.VerticalScrollBarVisibility="Visible">  
                                <i:Interaction.Behaviors>  
                                    <ic:EventTriggerBehavior EventName="SelectionChanged">  
                                            <ic:InvokeCommandAction Command="{x:Bind ViewModel.SaveSelectedItemsCommand}" CommandParameter="{x:Bind UserRoles.SelectedItems,Mode=OneWay}"/>  
                                    </ic:EventTriggerBehavior>  
                                </i:Interaction.Behaviors>  
                                </ListView>  

Answer 1

Hello @Boris Kleynbok
Welcome to Microsoft Q&A!

I see that your SaveSelectedItemsCommand is passed the parameter UserRoles.SelectedItems.
So, just need to create a new variable in the ViewModel to point to SelectedItems and execute Clear() when the selection needs to be cleared.

The following code implements the selection three times, then clears all selections.

XMAL:

<ic:EventTriggerBehavior EventName="SelectionChanged">  
    <ic:InvokeCommandAction  
                            Command="{x:Bind MainViewModel.ClearCommand,Mode=OneWay}"  
                            CommandParameter="{x:Bind UserRoles.SelectedItems,Mode=OneWay}"/>  
</ic:EventTriggerBehavior>  

ViewModel:

private RelayCommand<object> _clearCommand;  
        public RelayCommand<object> ClearCommand  
        {  
            get  
            {  
                _clearCommand = new RelayCommand<object>((s) =>  
                {  
  
                   var temp = s as IList<object>;  
                    if (temp.Count >= 3)  
                    {  
                        temp.Clear();  
                    }  
  
               });  
  
               return _clearCommand;  
            }  
            set  
            {  
                _clearCommand = value;  
            }  
        }  

Thank you.

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