Creating a highly manageable TreeView control using Microsoft Web TreeView control

namespace TreeView.Design.Controls
{
	using System;
	using System.Data;
	using System.Drawing;
	using System.Web;
	using System.Web.UI.WebControls;
	using System.Web.UI.HtmlControls;
	using System.Xml;

	using TreeView.Design.Base;
	/// <summary>
	///		Summary description for Company.
	/// </summary>
	public class Company : BaseControl, IHost
	{
		protected System.Web.UI.WebControls.TextBox txtCompany;
		protected System.Web.UI.WebControls.Button btnAdd;
		protected ObjectDump companyDump;

		private void Page_Load(object sender, System.EventArgs e)
		{
			// Put user code to initialize the page here
		}

		#region Web Form Designer generated code

		
		override protected void OnInit(EventArgs e)
		{
			//
			// CODEGEN: This call is required by the ASP.NET Web Form Designer.
			//
			InitializeComponent();
			base.OnInit(e);
		}
		
		/// <summary>
		///		Required method for Designer support - do not modify
		///		the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
		{
			this.btnAdd.Click += new System.EventHandler(this.btnAdd_Click);
			this.Load += new System.EventHandler(this.Page_Load);

		}
		#endregion

		#region IHost Members

	
		public void LoadTab(int PropertyID)
		{
			XmlDocument doc = new XmlDocument();
			doc.Load( Server.MapPath( "Data.xml" ) );

			_CompanyID = PropertyID;
			
			XmlNodeList nodeList = doc.GetElementsByTagName( "company" );
			
			foreach ( XmlNode node in nodeList )
			{
				int nodeID = Convert.ToInt32(  node.Attributes[ "id" ].Value );
				
				if( nodeID == PropertyID )
				{
					string companyName = node.Attributes[ "name" ].Value;

					Objects.Company company = new Objects.Company( nodeID, companyName );
					// load the object
					companyDump.LoadObject( company );
				}
			}
		}
		private int _CompanyID
		{
			get
			{
				return Convert.ToInt32(  base.ViewState[ "CompanyID" ] );
			}
			set
			{
				base.ViewState[ "CompanyID" ] = value;
			}
		}

		#endregion

		private void btnAdd_Click(object sender, System.EventArgs e)
		{
			AddNode( Server.MapPath(  "Data.xml" ) );			
			// notify observer ( in this case treeView )
			base.RaiseChangeEvent( true );
		
		}

		private void AddNode( string docPath )
		{
			XmlDocument doc = new XmlDocument();
			doc.Load( docPath );
			
			XmlNodeList nodeList = doc.GetElementsByTagName( "company" );
		
			foreach( XmlNode node in nodeList )
			{
	
				//XmlNode node = nodeList [ nodeList.Count - 1 ];

				int nodeID = Convert.ToInt32(  node.Attributes[ "id" ].Value );

				if( _CompanyID == nodeID )
				{
					
					XmlNode childNode = node.ChildNodes [ node.ChildNodes.Count -1 ];
				   
					int childID = Convert.ToInt32( 	childNode.Attributes[ "id" ].Value );

					int newID = ++childID;

					XmlElement deptElement = doc.CreateElement( "department" );
				
					// id attribute
					deptElement.SetAttribute( "id",newID.ToString() ) ;
					deptElement.SetAttribute( "name",txtCompany.Text.Trim() ) ;
				

					node.AppendChild( deptElement );
			
					string s = doc.InnerXml;
					
					doc.Save( docPath );

				}
			}// end foreach
	
		}
	}
}