Infragistics XamDataGrid Selection not working

This is a trivial post, but as I came across the same problem twice in one week I think it merits a post. The problem is that even though you have bound the grid's SelectedDataItem, the property is not set when the user clicks on the row.

Start a new WPF Application. We'll be working in C# today.

Let's set up a XamDataGrid to display a few rows and bind a TextBlock to the selected item.

<Window x:Class="SelectedDataItem.MainWindow"

        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

        xmlns:local="clr-namespace:SelectedDataItem"

        xmlns:igDP="http://infragistics.com/DataPresenter"

        mc:Ignorable="d"

        DataContext="{Binding RelativeSource={RelativeSource Self}}"

        Title="MainWindow" Height="350" Width="525">

    <StackPanel Orientation="Vertical">

        <igDP:XamDataGrid Height="250" DataSource="{Binding Items}" SelectedDataItem="{Binding SelectedItem}">

        </igDP:XamDataGrid>

        <TextBlock Text="{Binding SelectedItem.ItemName}"/>

    </StackPanel>

</Window>

-------------------------------------------------------------------------------

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Windows;

namespace SelectedDataItem

{

    public partial class MainWindow : Window, INotifyPropertyChanged

    {

        public class cItem

        {

            public String ItemName { get; set; }

        }

        public  List<cItem> Items { get; set; }

        private cItem _SelectedItem;

        public cItem SelectedItem

        {

            get { return _SelectedItem; }

            set { _SelectedItem = value;

                NotifyPropertyChanged("SelectedItem");

            }

        }

        public MainWindow()

        {

            Items = new List<cItem>();

            Items.Add(new cItem() { ItemName = "This is item 1" });

            Items.Add(new cItem() { ItemName = "This is item 2" });

            Items.Add(new cItem() { ItemName = "This is item 3" });

            InitializeComponent();

        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(String info)

        {

            if (PropertyChanged != null)

            {

                PropertyChanged(this, new PropertyChangedEventArgs(info));

            }

        }

    }

}

Obviously when we click on a line in the grid, the selected item's ItemName should be displayed in the TextBlock. But it doesn't work. Try it.

The problem is that even though it looks as though the row is being selected, it isn't. Try setting a breakpoint on the SelectedItem's setter - it's never called. 

Add the following XAML in the XamDataGrid. It tells the grid to select the record when the user clicks in a cell. I don't know why this isn't the default.

            <igDP:XamDataGrid.FieldSettings>

                <igDP:FieldSettings CellClickAction="SelectRecord"/>

            </igDP:XamDataGrid.FieldSettings>

Now try running the program again and selecting a record.

The answer's always simpler when you know it.