I think the best way to approach this problem is using the behaviors, here is an example - XamDataGridBehavior :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using System.Windows;
using System.Windows.Interactivity;
using System.Windows.Data;
 
using Infragistics.Windows.DataPresenter;
using Infragistics.Windows.DataPresenter.Events;
 
namespace Behaviors
{
    public class XamDataGridBehavior : Behavior<XamDataGrid>
    {
        public readonly static DependencyProperty SelectedItemsProperty =
            DependencyProperty.Register("SelectedItems", typeof(IEnumerable), typeof(XamDataGridBehavior),
              new FrameworkPropertyMetadata()
              {
                  BindsTwoWayByDefault = true,
                  DefaultUpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged,
              });
 
        public IEnumerable SelectedItems
        {
            get { return GetValue(SelectedItemsProperty) as IEnumerable; }
            set { SetValue(SelectedItemsProperty, value); }
        }
 
        public static readonly DependencyProperty SelectedItemProperty =
          DependencyProperty.Register("SelectedItem", typeof(object), typeof(XamDataGridBehavior),
              new FrameworkPropertyMetadata()
              {
                  BindsTwoWayByDefault = true,
                  DefaultUpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged,
              });
 
        public Object SelectedItem
        {
            get { return GetValue(SelectedItemProperty); }
            set { SetValue(SelectedItemProperty, value); }
        }
 
        protected override void OnAttached() 
        { 
            base.OnAttached();
 
            AssociatedObject.SelectedItemsChanged += new OnSelectedItemsChanged;
            
        }
 

        void OnSelectedItemsChanged(object sender, SelectedItemsChangedEventArgs e)

        {

            XamDataGrid dataGrid = (sender as XamDataGrid);

            SelectedItems = (from item in dataGrid.SelectedItems
                            select (item as DataRecord).DataItem).ToList();

            if (dataGrid.SelectedItems.DataPresenter.ActiveDataItem != null)

            {

                SelectedItem = dataGrid.SelectedItems.DataPresenter.ActiveDataItem;

            }

        }

          
        
        protected override void OnDetaching() 
        {
            AssociatedObject.SelectedItemsChanged -= OnSelectedItemsChanged; 
            
            base.OnDetaching(); 
        } 
    }
}

XAML would be:

<i:Interaction.Behaviors>
    <be:XamDataGridBehavior SelectedItem="{Binding Path=VMSelectedItem}"/>
</i:Interaction.Behaviors>
 
Where VMSelectedItem is the viewmodel SelectItem you are interested in.
 
 
That's pretty much it, cheers :)
 
- Shams

You need to inherit from XamDataGrid and add a DependencyProperty used for Binding the seleted itemS:

private readonly static DependencyProperty SelectedProperty = DependencyProperty.Register("Selected", typeof(IEnumerable), typeof(DataGrid));
 
        public  IEnumerable Selected 
        {
            get { return GetValue(SelectedProperty) as IEnumerable; }
            set { SetValue(SelectedProperty, value); }
        }
 
        public DataGrid()
        {
            SelectedItemsChanged += new EventHandler<SelectedItemsChangedEventArgs>(DataGrid_SelectedItemsChanged);
        }
 
        private void DataGrid_SelectedItemsChanged(object sender, SelectedItemsChangedEventArgs e)
        {
            List<object> selectedItems = new List<object>();
 
            foreach (object selectedItem in base.SelectedItems)
            {
                if (selectedItem is Cell)
                    selectedItems.Add(((selectedItem as Cell).Record as DataRecord).DataItem);
 
                else if (selectedItem is DataRecord)
                        selectedItems.Add((selectedItem as DataRecord).DataItem);
            }
 
            Selected = selectedItems as IEnumerable;
        }

}

Then in Xaml you can do:

<controls:DataGrid DataSource="{Binding ...}" Selected="{Binding Selected, Mode=OneWayToSource}">

Refer to following URL :

http://help.infragistics.com/Help/NetAdvantage/WPF/2007.2/CLR3.X/html/xamDataGrid_Accessing_Cell_Values_in_the_Active_Record.html

Hope this will be usefull

Sohel

I've tried the activerecord property and that only returns a single, not several if you have multiple row selection enabled.