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DHTML Tree View of Arbitrary Depth using AJAX

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25 Aug 20054 min read 186.4K   2.1K   84  
This article provides a gentle introduction to AJAX by applying that technology to significantly enhance a tree previously rendered using JavaScript.
// Copyright (c)2005 Rewritten Software.  http://www.rewrittensoftware.com
// This script is supplied "as is" without any form of warranty. Rewritten Software 
// shall not be liable for any loss or damage to person or property as a result of using this script.
// Use this script at your own risk!
// You are licensed to use this script free of charge for commercial or non-commercial use providing you do not remove 
// the copyright notice or disclaimer.

namespace WebApplication1
{
	using System;
	using System.Data;
	using System.Drawing;
	using System.Web;
	using System.Web.UI.WebControls;
	using System.Web.UI.HtmlControls;
	using System.ComponentModel;			// Required for Designer attribute

	/// <summary>
	///	Tree View Class
	/// </summary>
	[Designer(typeof(TreeView))]
	public class TreeView : System.Web.UI.UserControl
	{
		private Tree tree;

		/// <summary>
		/// Tree to display in the control
		/// </summary>
		public Tree DisplayTree
		{
			get { return tree; }
			set { tree = value; }
		}

		private bool delayLoad = true;
    
		/// <summary>
		/// Set delay load if the output of the tree should be 
		/// staged using AJAX techniques.
		/// </summary>
		public bool DelayLoad
		{
			get { return delayLoad; }
			set { delayLoad = value; }
		}
	
		private void Page_Load(object sender, System.EventArgs e)
		{
			if (DisplayTree == null)
				throw new HttpException("DisplayTree must not be null in tree build.");
        
			// Store the tree data in the session to allow access at treefill time. 
			if (delayLoad)
				Session["tree" + DisplayTree.ID] = DisplayTree;
		}

		protected override void Render(System.Web.UI.HtmlTextWriter writer)
		{
			// Reference javascript for AJAX behaviour and tree toggling
			writer.Write("<script language=\"Javascript\" type=\"text/javascript\" src=\"TreeToggle.js\"></script>");

			// Write the root node
			if (DisplayTree != null)
				DisplayTree.Root.WriteNode(writer, DisplayTree.ID, delayLoad);

		}



		#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.Load += new System.EventHandler(this.Page_Load);
		}
		#endregion
	}
}

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Written By
Architect Webefinity
Australia Australia
Adrian is current the Solution Architect at CubeBuild.com.

The core of CubeBuild is a website and application platform that is pluggable into ASP.NET MVC. Any MVC application can have content authoring added to its pages with little effort, and new content types are created using IronPython.NET open source components.

We are currently deploying a Point of Service (Web based POS) built on CubeBuild which allows a single web channel for face-to-face sales, and sales through your online store. All from a single inventory base, and from any device.

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