using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using Telerik.Web.UI;
using System.Data.SqlClient;

public class MyCustomFilteringColumnCS : GridBoundColumn
{
	public static string ConnectionString
        {
            get { return ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString; }
        }

        //RadGrid will call this method when it initializes the controls inside the filtering item cells
        protected override void SetupFilterControls(TableCell cell)
        {
            base.SetupFilterControls(cell);
            cell.Controls.RemoveAt(0);
            RadComboBox combo = new RadComboBox();
            combo.ID = ("RadComboBox1" + this.UniqueName);
            combo.ShowToggleImage = false;
            combo.Skin = "Office2007";
            combo.EnableLoadOnDemand = true;
            combo.AutoPostBack = true;
            combo.MarkFirstMatch = true;
            combo.Height = Unit.Pixel(100);
            combo.ItemsRequested += this.list_ItemsRequested;
            combo.SelectedIndexChanged += this.list_SelectedIndexChanged;
            cell.Controls.AddAt(0, combo);
            cell.Controls.RemoveAt(1);
        }

        //RadGrid will cal this method when the value should be set to the filtering input control(s)
        protected override void SetCurrentFilterValueToControl(TableCell cell)
        {
            base.SetCurrentFilterValueToControl(cell);
            RadComboBox combo = (RadComboBox)cell.Controls[0];
            if ((this.CurrentFilterValue != string.Empty))
            {
                combo.Text = this.CurrentFilterValue;
            }
        }

        //RadGrid will cal this method when the filtering value should be extracted from the filtering input control(s)
        protected override string GetCurrentFilterValueFromControl(TableCell cell)
        {
            RadComboBox combo = (RadComboBox)cell.Controls[0];
            return combo.Text;
        }

        private void list_ItemsRequested(object o, RadComboBoxItemsRequestedEventArgs e)
        {
            ((RadComboBox)o).DataTextField = this.DataField;
            ((RadComboBox)o).DataValueField = this.DataField;
            ((RadComboBox)o).DataSource = GetDataTable("SELECT DISTINCT " + this.UniqueName + " FROM Customers WHERE " + this.UniqueName + " LIKE '" + e.Text + "%'");
            ((RadComboBox)o).DataBind();
        }

        private void list_SelectedIndexChanged(object o, RadComboBoxSelectedIndexChangedEventArgs e)
        {
            GridFilteringItem filterItem = (GridFilteringItem)((RadComboBox)o).NamingContainer;
            if ((this.UniqueName == "Index"))
            {
                //this is filtering for integer column type 
                filterItem.FireCommandEvent("Filter", new Pair("EqualTo", this.UniqueName));
            }
            //filtering for string column type
            filterItem.FireCommandEvent("Filter", new Pair("Contains", this.UniqueName));
        }

        public static DataTable GetDataTable(string query)
        {
            SqlConnection conn = new SqlConnection(ConnectionString);
            SqlDataAdapter adapter = new SqlDataAdapter();
            adapter.SelectCommand = new SqlCommand(query, conn);

            DataTable myDataTable = new DataTable();

            conn.Open();
            try
            {
                adapter.Fill(myDataTable);
            }
            finally
            {
                conn.Close();
            }
            return myDataTable;
        }

}