To improve the page speed and reducing the large data handling load on the server we usually need to implement custom Paging and Sorting. Today I am going to tell how this can be done with RadGrid.

Step 1: Add "AllowPaging='True'" and  "AllowCustomPaging='True'" for enabling custom paging & "AllowSorting='true' "AllowCustomSorting='True'" for enabling custom sorting, attributes to the RadGrid element.

Step 2: We specified to the RadGrid control that we are handling paging and sorting on our own. Now we need to register an event i.e. "OnNeedDataSource". Your RadGrid will look like below:

<telerik:RadGrid runat="server" ID="RgProducts" 
    AllowSorting="true" AllowCustomSorting="True"
    AllowPaging="True" AllowCustomPaging="True" VirtualItemCount="1000"
    OnNeedDataSource="RgProducts_OnNeedDataSource" OnSortCommand="RgProducts_OnSortCommand">
    <ClientSettings>
    </ClientSettings>
    <MasterTableView TableLayout="Fixed"></MasterTableView>
</telerik:RadGrid>

Step 3: Its time to write backend logic for applying custom paging and sorting. You:

protected void RgProducts_OnNeedDataSource(object sender, GridNeedDataSourceEventArgs e)
{	
	var sortByColumn = "Id";
	var sortByDirection = "ASC";
	if (RgProducts.MasterTableView.SortExpressions.Count > 0)
	{
		var sortExpression = RgProducts.MasterTableView.SortExpressions[0];
		sortByColumn = sortExpression.FieldName;
		sortByDirection = sortExpression.SortOrderAsString();
	}
	
	var pageSize = RgProducts.PageSize;
	var startRowIndex = RgProducts.CurrentPageIndex * pageSize;
	
	var sortExp = string.Format("{0} {1}", sortByColumn, sortByDirection);
	
	RgProducts.VirtualItemCount = Repository.Instance.Products.Count();  //For letting the grid know how many items are there.
	RgProducts.DataSource = Repository.Instance.Products.OrderBy(sortExp) // This OrderBy is a method of open source library: https://www.nuget.org/packages/System.Linq.Dynamic
		.Skip(startRowIndex)
		.Take(pageSize)
		.ToList();
}