MvvmLight EventToCommand and WPFToolkit DataGrid double-click

Question

Trying to figure out how to use EventToCommand to set a datagrid double click handler for rows. The command lives in the viewmodel for each row. Just that much out of my experience, since I haven't used interactions yet.

Thanks.

I would have used mvvmlight tag, but I don't have high enough rep yet to make new tags.

Answer 1

This would be the solution if the Command lives on the "GridVieModel" and not on the "RowViewModel".

    <Window...    
         ...xmlns:dg="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit" 
            xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" 
            xmlns:GalaSoft_MvvmLight_Command="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Extras">
         <dg:DataGrid x:Name="dg">
                    <i:Interaction.Triggers>
                        <i:EventTrigger EventName="MouseDoubleClick">
                            <GalaSoft_MvvmLight_Command:EventToCommand CommandParameter="{Binding SelectedItem, ElementName=dg}" Command="{Binding Path=SelectCommand, Mode=OneWay}"/>
                        </i:EventTrigger>
                    </i:Interaction.Triggers>
            </dg:DataGrid>
    </Window>

You could create a rowview since the row also has its own viewmodel and use the mousedoubleclick event of a child element of the row (container) in the rowview.

Or you create a converter for your command binding:

<GalaSoft_MvvmLight_Command:EventToCommand Command="{Binding SelectedItem, ElementName=dg, Mode=OneWay, Converter=...}"/>

The converter then would check if the selectedItem is of the required type to return the command (Something like ISelectCommandable with a RelayCommand Property)

Answer 2

In case anyone comes looking here and wonders how I ended up doing it w/o EventToCommand

public class DataGridAttachedBehaviors
{
   #region DoubleClick

   public static DependencyProperty OnDoubleClickProperty = DependencyProperty.RegisterAttached(
       "OnDoubleClick",
       typeof(ICommand),
       typeof(DataGridAttachedBehaviors),
       new UIPropertyMetadata(DataGridAttachedBehaviors.OnDoubleClick));

   public static void SetOnDoubleClick(DependencyObject target, ICommand value)
   {
      target.SetValue(DataGridAttachedBehaviors.OnDoubleClickProperty, value);
   }

   private static void OnDoubleClick(DependencyObject target, DependencyPropertyChangedEventArgs e)
   {
      var element = target as Control;
      if (element == null)
      {
         throw new InvalidOperationException("This behavior can be attached to a Control item only.");
      }

      if ((e.NewValue != null) && (e.OldValue == null))
      {
         element.MouseDoubleClick += MouseDoubleClick;
      }
      else if ((e.NewValue == null) && (e.OldValue != null))
      {
         element.MouseDoubleClick -= MouseDoubleClick;
      }
   }

   private static void MouseDoubleClick(object sender, MouseButtonEventArgs e)
   {
      UIElement element = (UIElement)sender;
      ICommand command = (ICommand)element.GetValue(DataGridAttachedBehaviors.OnDoubleClickProperty);
      command.Execute(null);
   }

   #endregion DoubleClick

  #region SelectionChanged
  //removed
  #endregion
}

In my xaml:

<dg:DataGrid.RowStyle>
   <Style BasedOn="{StaticResource DataGridDemoRowStyle}"           
          TargetType="{x:Type dg:DataGridRow}">
       <Setter Property="skins:DataGridAttachedBehaviors.OnDoubleClick"
               Value="{Binding Recall}" />
   </Style>
</dg:DataGrid.RowStyle>