ComboBox / LinqDataSource

This example demonstrates how to bind RadComboBox to LinqDataSource and Linq to SQL data classes.

The first combobox is bound declaratively to the LinqDataSource control. Filtering is performed using the Where property of the data source control:

protected void RadComboBox1_OnItemsRequested(object o, RadComboBoxItemsRequestedEventArgs e)
{
	LinqDataSource1.Where = "ContactName.StartsWith(\"" + e.Text + "\")";
	RadComboBox1.DataBind();
}

The second combobox demonstrates how to implement paging on the database using LINQ:

protected void RadComboBox2_OnItemsRequested(object o, RadComboBoxItemsRequestedEventArgs e)
{
	NorthwindDataContext context = new NorthwindDataContext();

	var allCustomers = from customer in context.Customers
					   orderby customer.ContactName
					   select customer;
	
	if (!String.IsNullOrEmpty(e.Text))
	{
		allCustomers = from customer in context.Customers
					   where customer.ContactName.StartsWith(e.Text)
					   orderby customer.ContactName
					   select customer;
	}

	var customers = allCustomers.Skip(e.NumberOfItems).Take(10);
	RadComboBox2.DataSource = customers;
	RadComboBox2.DataBind();

	int endOffset = e.NumberOfItems + customers.Count();
	int totalCount = allCustomers.Count();

	if (endOffset == totalCount)
		e.EndOfItems = true;


	e.Message = String.Format("Items 1-{0} out of {1}", endOffset, totalCount);
}