VirtualQueryableCollectionView inserting issue in UI for Silverlight GridView

Petr Šatka

21 posts

Member since:
Mar 2011

Posted 27 Jun 2011 Link to this post

Hi Telerik.
I can not insert new rows into VirtualQueryableCollectionView. The same code with the WPF GridView works correctly. But Silverlight GridView is replacing the rows instead of inserting.

I attached a screenshot of grids after two inserts. The first grid is Silverlight, the second grid is WPF.

Thank you for your help.

Best regards
Peter

Sample code
Xaml

<Button Content="Insert" Click="Button_Click"/>

<telerik:RadGridView x:Name="rgv1" Grid.Row="1"/>

Code behind

public AppView() {

InitializeComponent();

var source = new List<int>();

source.Add(1);

source.Add(2);

this.rgv1.ItemsSource = new VirtualQueryableCollectionView(source) { LoadSize = 10 };

}

private void Button_Click(object sender, RoutedEventArgs e) {

((VirtualQueryableCollectionView)this.rgv1.ItemsSource).Insert(0, 3);

}

SilverlightVsWpf.png

Rossen Hristov

Admin

2477 posts

Posted 28 Jun 2011 Link to this post

Hello Petr Šatka,

Why don't you try inserting in the source collection and not directly in the CQCV?

Also, try making the source collection an ObservableCollection<T> one instead of List<T>.

Greetings,
Ross
the Telerik team

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Petr Šatka

21 posts

Member since:
Mar 2011

Posted 28 Jun 2011 Link to this post

Hello Ross,
I have tried to use the ObservableCollection, but unfortunately it does not work. Gridview does not display the inserted rows.

Best regards
Peter

Sample code




namespace RadControlsSilverlightApp1 {
  public partial class MainPage : UserControl {
    public class TestClass {
      public int Property {
        get;
        set;
      }
    }
 
    ObservableCollection<TestClass> source = new ObservableCollection<TestClass>();
 
    public MainPage() {
      InitializeComponent();
      source.Add(new TestClass() { Property = 1 });
      source.Add(new TestClass() { Property = 2 });
      this.rgv1.ItemsSource = new VirtualQueryableCollectionView(source) { LoadSize = 10 };
    }
 
    private void Button_Click(object sender, RoutedEventArgs e) {
      //((VirtualQueryableCollectionView)this.rgv1.ItemsSource).Insert(0, new TestClass() { Property = 3 });
      source.Insert(0, new TestClass() { Property = 3 });
    }
  }
}

Petr Šatka

21 posts

Member since:
Mar 2011

Posted 28 Jun 2011 Link to this post

EDIT : I have changed the sample code.

Rossen Hristov

Admin

2477 posts

Posted 28 Jun 2011 Link to this post

Hello Petr Šatka,

The way VQCV works is that someone has to actually request an item and it will then load it on demand. Can you try calling the Rebind method of RadGridView after you insert the new items?

Greetings,
Ross
the Telerik team

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Petr Šatka

21 posts

Member since:
Mar 2011

Posted 28 Jun 2011 Link to this post

Hello Ross,
With the Rebind() the GridView is replacing rows. As in the first case, Gridview shows the two rows only.

Best regards
Peter

Sample code

private void Button_Click(object sender, RoutedEventArgs e) {

//((VirtualQueryableCollectionView)this.rgv1.ItemsSource).Insert(0, new TestClass() { Property = 3 });

source.Insert(0, new TestClass() { Property = 3 });

rgv1.Rebind();

}

Maya

Admin

4062 posts

Posted 29 Jun 2011 Link to this post

Hi Petr Šatka,

You may insert an item like follows:

private void RadButton_Click(object sender, System.Windows.RoutedEventArgs e)

{

source.Insert(0, new Order_Detail() { OrderID = source.Count });

vqcv.VirtualItemCount = source.Count;

}

Still, I am sending you a sample project illustrating the suggested approach.
All the best,
Maya
the Telerik team

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SilverlightApplication1.zip

Petr Šatka

21 posts

Member since:
Mar 2011

Posted 29 Jun 2011 Link to this post

Thank you Maya, but this solution has a drawback. After changing the VirtualItemCount property vqcv invokes an Event with the NotifyCollectionChangedAction.Reset attribute. This causes a reset of GridView and focus of the current row is lost. This behavior is not user friendly when inserting somewhere in the middle of the large collection. Standard insert into WPF vqcv does not reset the GridView.

Best regards
Peter

Petr Šatka

21 posts

Member since:
Mar 2011

Posted 12 Jul 2011 Link to this post

Hi,

Well let me ask differently. Is there a way how to get the same behavior with silverlight RadGridView and VQCV as shown in the video?
http://www.youtube.com/watch?v=d-sc0qZYW28

Thank you for your reply.

Best regards
Petr

Maya

Admin

4062 posts

Posted 18 Jul 2011 Link to this post

Hi Petr Šatka,

Currently, the illustrated requirements cannot be accomplished with VirtualQuerableCollectionView. However, we will consider supporting such a scenario.

Kind regards,
Maya
the Telerik team

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Petr Šatka

21 posts

Member since:
Mar 2011

Posted 18 Jul 2011 Link to this post

Hi Maya,
Thank you for your reply. However, I have one more question. It is possible to implement a custom virtualized collection? I tried to use a similar solution to this http://www.codeproject.com/KB/WPF/WpfDataVirtualization.aspx, that uses UI virtualization. Unfortunately the RadGridView always iterates through the entire collection. What conditions must my virtualized collection meet to work with the Silverlight RadGridView?

Best regards,
Peter