Load items in the ItemsLoading event of VirtualQueryableCollectionView manually When Used in RadGridView

Updated on Sep 15, 2025

Environment

Product	RadGridView for WPF
Version	2024.3.821

Description

How to manually load data in RadGridView using the VirtualQueryableCollectionView and its ItemsLoading event, without working with IQueryable collection source.

This approach is meaningful when you don't want to load all your data in-memory, but fetch it in the ItemsLoading event handler.

Solution

To do this, you can initialize the VirtualQueryableCollectionView with an empty collection source which later will be populated with data.

To adjust the total items count, set the VirtualItemCount property of the collection view.

In the ItemsLoading event handler, you can manually fetch and add items in the collection view.

Setting up the VirtualQueryableCollectionView

C#

	public MainWindow()
	{
		InitializeComponent();
		
		var vqcv = new VirtualQueryableCollectionView(new ObservableCollection<RowInfo>()) { LoadSize = 10, VirtualItemCount = 1000  };            
		vqcv.ItemsLoading += VirtualQueryableCollectionView_ItemsLoading;	
		this.gridView.ItemsSource = vqcv;
	}

	private void VirtualQueryableCollectionView_ItemsLoading(object? sender, VirtualQueryableCollectionViewItemsLoadingEventArgs e)
	{
		var vqcv = (VirtualQueryableCollectionView)sender;
		var newItems = // fetch the new portion of items here
		foreach (var item in newItems)
		{
			vqcv.Add(item);
		}
	}