VM.IsSelected set to false

[Chad]

We're binding the IsSelected from our VM to the IsSelected of the grid row.

When we reload and restore the IsSelected on the VM the IsSelected get set from true to false. (stack trace below)

We have multiselect set to true on the grid. Can anyone demystify the stack below as to why this is happening?

Thanks

<Style TargetType="telerik:GridViewRow">
    <Setter Property="IsSelected" Value="{Binding Path=IsSelected, Mode=TwoWay}"/>

this.UseCase.Items.Clear();

this.UseCase.AddItems(this._products);

 this.UseCase.FrameViewModel.ProductGridVM.Products = this.UseCase.Items;

We're restoring IsSelected after this.


>   Union.Catalog.Client.Product.ProductVMBaseBase.IsSelected.set   C#
    [Native to Managed Transition]
    MS.Internal.Data.PropertyPathWorker.SetValue
    MS.Internal.Data.ClrBindingWorker.UpdateValue
    System.Windows.Data.BindingExpression.UpdateSource
    System.Windows.Data.BindingExpressionBase.UpdateValue
    System.Windows.Data.BindingExpression.UpdateOverride
    System.Windows.Data.BindingExpressionBase.Update
    System.Windows.Data.BindingExpressionBase.ProcessDirty
    System.Windows.Data.BindingExpressionBase.Dirty
    System.Windows.Data.BindingExpressionBase.SetValue
    System.Windows.DependencyObject.SetValueCommon
    System.Windows.DependencyObject.SetValue
    Telerik.Windows.Controls.DataControl.PersistIsSelectedProperty
    Telerik.Windows.Controls.GridView.GridViewDataControl.PrepareContainerForItemOverride
    Telerik.Windows.Controls.GridView.BaseItemsControl.Telerik.Windows.Controls.GridView.IGeneratorHost.PrepareItemContainer
    Telerik.Windows.Controls.GridView.GridViewItemContainerGenerator.System.Windows.Controls.Primitives.IItemContainerGenerator.PrepareItemContainer
    Telerik.Windows.Controls.GridView.GridViewVirtualizingPanel.NestedLayoutStrategy.InsertContainer
    Telerik.Windows.Controls.GridView.GridViewVirtualizingPanel.NestedLayoutStrategy.InsertNewContainer
    Telerik.Windows.Controls.GridView.GridViewVirtualizingPanel.NestedLayoutStrategy.AddContainerFromGenerator
    Telerik.Windows.Controls.GridView.GridViewVirtualizingPanel.NestedLayoutStrategy.GenerateNextChild
    Telerik.Windows.Controls.GridView.GridViewVirtualizingPanel.NestedLayoutStrategy.MeasureOverride
    Telerik.Windows.Controls.GridView.GridViewVirtualizingPanel.MeasureOverride
    System.Windows.FrameworkElement.MeasureCore
    System.Windows.UIElement.Measure
    System.Windows.ContextLayoutManager.UpdateLayout
    System.Windows.ContextLayoutManager.UpdateLayoutCallback
    System.Windows.Media.MediaContext.InvokeOnRenderCallback.DoWork
    System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks
    System.Windows.Media.MediaContext.RenderMessageHandlerCore
    System.Windows.Media.MediaContext.RenderMessageHandler
    System.Windows.Threading.ExceptionWrapper.InternalRealCall
    MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen
    System.Windows.Threading.DispatcherOperation.InvokeImpl
    System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext
    System.Threading.ExecutionContext.RunInternal
    System.Threading.ExecutionContext.Run
    System.Threading.ExecutionContext.Run
    System.Windows.Threading.DispatcherOperation.Invoke
    System.Windows.Threading.Dispatcher.ProcessQueue
    System.Windows.Threading.Dispatcher.WndProcHook
    MS.Win32.HwndWrapper.WndProc
    MS.Win32.HwndSubclass.DispatcherCallbackOperation
    System.Windows.Threading.ExceptionWrapper.InternalRealCall
    MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen
    System.Windows.Threading.Dispatcher.LegacyInvokeImpl
    MS.Win32.HwndSubclass.SubclassWndProc
    [Native to Managed Transition]
    [Managed to Native Transition]
    System.Windows.Threading.Dispatcher.PushFrameImpl
    System.Windows.Threading.Dispatcher.PushFrame
    System.Windows.Threading.Dispatcher.Run
    System.Windows.Application.RunDispatcher
    System.Windows.Application.RunInternal
    System.Windows.Application.Run
    System.Windows.Application.Run
    UnionShell.App.Main C#

[Nick]

Hi Tjaart,

The problem is that the IsSelected property of the GridView row is a visual property that is used to identify if a Row is selected and thus put it in the correct visual state. Due the the UI Virtualization however, this porperty is unreliable on data level as the same row object is reused for multiple items. 

You can use the SelectedItems property of RadGridView to keep synchronization between the data and the actual selected items.

Hope this makes sense. 

Regards,
Nick
Telerik

 

 

[Chad]

Thanks for the info Nick.

We're using the same pattern for the TreeView without a glitch... so far.

Does it mean we're running the risk of the TreeView failing at some point?

<Style x:Key="TreeViewItemStyle" TargetType="{x:Type t:RadTreeViewItem}" mc:Ignorable="d"
       d:DataContext="{d:DesignInstance IsDesignTimeCreatable=True, Type=unionCategoryTree:CategoryVM}">
    <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />

[Nick]

Hi Tjaart,

Basically the RadTreeView and RadGridVew(RadTreeListView shares same code base) have different layout and rendering strategies so the approach will probably work with RadTreeView. Nevertheless, using it with RadGridView or RadTreeListView is not recommended. 

Regards,
Nick
Telerik

 

 

[Chad]

Thanks Nick