Exception when removing element

[Doug]

Hi

I have a problem with the databound listbox, when I have one element in the list and I remove it, and I want to add a new element instead I get the following exception:

  at Telerik.Windows.Controls.RadDataBoundListBox.GetLastItemCacheIndex()
   at Telerik.Windows.Controls.VirtualizationStrategy.RefreshViewportOnItemAdded(IDataSourceItem addedItem)
   at Telerik.Windows.Controls.RadVirtualizingDataControl.UpdateViewportOnItemsChange(NotifyCollectionChangedEventArgs e)
   at Telerik.Windows.Controls.RadVirtualizingDataControl.OnItemsChanged(NotifyCollectionChangedEventArgs e)
   at Telerik.Windows.Controls.RadDataBoundListBox.OnItemsChanged(NotifyCollectionChangedEventArgs e)
   at Telerik.Windows.Controls.RadVirtualizingDataControl.OnListSource_CollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)

I have also created a sample application showing what I am doing:

Xaml:
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <Telerik:RadDataBoundListBox Grid.Row="1" Name="TestListbox" DataVirtualizationMode="OnDemandAutomatic" CacheMode="BitmapCache" ItemsSource="{Binding TestStringCollection}">
                <Telerik:RadDataBoundListBox.ItemTemplate>
                    <DataTemplate>
                        <TextBlock Text="{Binding}" />
                    </DataTemplate>
                </Telerik:RadDataBoundListBox.ItemTemplate>
            </Telerik:RadDataBoundListBox>
        </Grid>


C#:

namespace RadControlsWindowsPhoneApp1
{
    public partial class MainPage : PhoneApplicationPage
    {
        public ObservableCollection<string> TestStringCollection { get; private set; }


        // Constructor
        public MainPage()
        {
            InitializeComponent();


            TestStringCollection = new ObservableCollection<string>();
            TestStringCollection.Add("a");


            DataContext = this;
        }


        private void TestButtonClick(object sender, EventArgs e)
        {
            TestStringCollection.Remove("a");
            TestStringCollection.Add("b"); //Exception here
        }
    }
}

If I have 2 items in the listbox this doesn't happen.

I would like you to offer a work around this and to fix it as soon as possible. Thanks in advance.

Best Regards Doug

[Deyan]

Hi Doug,

Thanks for writing and for reporting this issue.

We have been able to reproduce it and to identify the reason for it.

A fix will be available in the upcoming Q2 2012 SP1 which is due to in a week.

Let me know in case you have further questions or need assistance.

Greetings,
Deyan
the Telerik team