Hi,

I'm trying out the new Data Virtualization feature explained in the following blog post:
http://blogs.telerik.com/vladimirenchev/posts/10-12-09/server_sorting_and_filtering_with_wcf_ria_services_and_telerik_data_virtualization_for_silverlight.aspx

But I'm experiencing several issues:

1. If I try to filter the collection and specify a value that I know doesn't exist in the collection. The grid of course becomes empty, but then if I try to alter or clear the filter nothing happens, the grid stays empty.

2. If I goto edit mode on a row by double clickin a cell and then hold down the down arrow to start "paging" I evetually get the following exception:

3. Using pageup/pagedown to scroll the collection will eventually make the grid lose focus.

 Tomas

We do not have such plans - can you clarify why you need this? 

Hi Vlad,

One issue we're seeing here is that if you have a GridView with AutoGenerateColumns set to True the column names will not be shown before the grid is actually bound to any data. This isn't such a big deal if you load the grid on inital load of the page (you still get an ugly flash as the columns appear though). But if the grid is populated at a later time from a designing perspective it doesn't look good to have a completely blank grid and then suddenly when it's populated with data the columns appear.

Another small issue if AutoGenerateColumns is set to False and you specify the columns in xaml you will get binding errors in Visual Studio output window on initial load as it cannot find the bindings at first.

If there's anyway around theese issues I would be more okay with a non generic version than what I currently am.

Tomas

 You can set Enumerable.Empty<T>() for the initial value/data context to avoid the first problem. We've fixed the second problem immediately and the fix will be part of our next internal build (Monday). I've added 2000 Telerik points to your account. You can use also the fixed version with predefined columns (not auto-generated) to avoid the first problem. 

 It seems that you are right! Currently there is no easy way to achieve this with auto-generated columns (at least without some ugly code) and we will do our best to improve this. The only option I can suggest you for now is to use the latest build with manually declared columns (in XAML or programmatically created).

 Thank you very much for this report - I've added 2000 Telerik points to your account. We've found what is causing the error (nested properties + virtual collection + grid validation) and the issue was fixed immediately. The fix will be part of our next internal build - Monday. 

 Can you provide more info about the problem? Can you send us an example application where we can check this? 

 Can you check if you are applying filter descriptors similar our demos? 

if (View.FilterDescriptors.Count == 0)

 You can check ItemsLoading event handler code in our demos for more info. 

Is this the code in Itemloading load in the demo - not sure how this will help filter? I wanted to know if client side filter can be done with virtualview and radgridview. If not we can try to find other solutions. Thanks for the help.

context.Load<Order_Detail>(query.Skip(e.StartIndex).Take(e.ItemCount)).Completed += (sender, args) =>

 {

var lo = (LoadOperation)sender;

 if (lo.TotalEntityCount != -1 && lo.TotalEntityCount != view.VirtualItemCount)

 {

 view.VirtualItemCount = lo.TotalEntityCount;

 }

 view.Load(e.StartIndex, lo.Entities);

 };

 Are you using the generic version of the VirtualQueryableCollectionView?