Dynamic sitemap provider for .NET 2.0

DynamicSiteMapProvider.cs

/*	
 * DynamicSiteMapProvider 
 * 
 * Created by Simon Harriyott http://harriyott.com
 * More details at http://harriyott.com/2007/03/adding-dynamic-nodes-to-aspnet-site
 * 
 * DynamicSiteMapProvider is a class that adds new
 * items to a site map at runtime. The filename of 
 * the existing xml sitemap is set in the Web.Config
 * file. This file is loaded, and extra nodes can
 * be added to the xml (by you) before the new xml is
 * converted into a site map node structure, and passed
 * back to the calling object.
 * 
 * Feel free to use and modify this class for personal, 
 * non-profit or commercial use, without charge. I would
 * appreciate you leaving this comment here. I'd also 
 * appreciate a link to my blog from your website, but 
 * I'll leave that up to you.
 * 
 */

#region Using
using System;
using System.Web;
using System.Web.UI;
using System.Xml;
#endregion

namespace Harriyott.Web
{
	/// <summary>
	/// Adds new items to an existing xml site map at runtime.
	/// Modify this class to add your own items.
	/// </summary>
	public class DynamicSiteMapProvider : StaticSiteMapProvider
	{
		public DynamicSiteMapProvider()	: base()
		{

		}

		private String _siteMapFileName;
		private SiteMapNode _rootNode = null;

		// Return the root node of the current site map.
		public override SiteMapNode RootNode
		{
			get
			{
				return BuildSiteMap();
			}
		}

		/// <summary>
		/// Pull out the filename of the site map xml.
		/// </summary>
		/// <param name="name"></param>
		/// <param name="attributes"></param>
		public override void Initialize(string name, System.Collections.Specialized.NameValueCollection attributes)
		{
			base.Initialize(name, attributes);
			_siteMapFileName = attributes["siteMapFile"];
		}

		private const String SiteMapNodeName = "siteMapNode";

		public override SiteMapNode BuildSiteMap()
		{
			lock (this)
			{
				if (null == _rootNode)
				{
					Clear();
					
					// Load the sitemap's xml from the file.
					XmlDocument siteMapXml = LoadSiteMapXml();
					
					// Create the first site map item from the top node in the xml.
					XmlElement rootElement = 
						(XmlElement)siteMapXml.GetElementsByTagName(
						SiteMapNodeName)[0];
					
					// This is the key method - add the dynamic nodes to the xml
					AddDynamicNodes(rootElement);
					
					// Now build up the site map structure from the xml
					GenerateSiteMapNodes(rootElement);
				}
			}
			return _rootNode;
		}

		/// <summary>
		/// Open the site map file as an xml document.
		/// </summary>
		/// <returns>The contents of the site map file.</returns>
		private XmlDocument LoadSiteMapXml()
		{
			XmlDocument siteMapXml = new XmlDocument();
			siteMapXml.Load(AppDomain.CurrentDomain.BaseDirectory + _siteMapFileName);
			return siteMapXml;
		}

		/// <summary>
		/// Creates the site map nodes from the root of 
		/// the xml document.
		/// </summary>
		/// <param name="rootElement">The top-level sitemap element from the XmlDocument loaded with the site map xml.</param>
		private void GenerateSiteMapNodes(XmlElement rootElement)
		{
			_rootNode = GetSiteMapNodeFromElement(rootElement);
			AddNode(_rootNode);
			CreateChildNodes(rootElement, _rootNode);
		}

		/// <summary>
		/// Recursive method! This finds all the site map elements
		/// under the current element, and creates a SiteMapNode for 
		/// them.  On each of these, it calls this method again to 
		/// create it's new children, and so on.
		/// </summary>
		/// <param name="parentElement">The xml element to iterate through.</param>
		/// <param name="parentNode">The site map node to add the new children to.</param>
		private void CreateChildNodes(XmlElement parentElement, SiteMapNode parentNode)
		{
			foreach (XmlNode xmlElement in parentElement.ChildNodes)
			{
				if (xmlElement.Name == SiteMapNodeName)
				{
					SiteMapNode childNode = GetSiteMapNodeFromElement((XmlElement)xmlElement);
					AddNode(childNode, parentNode);
					CreateChildNodes((XmlElement)xmlElement, childNode);
				}
			}
		}


		/// <summary>
		/// The key method. You can add your own code in here
		/// to add xml nodes to the structure, from a 
		/// database, file on disk, or just from code.
		/// To keep the example short, I'm just adding from code.
		/// </summary>
		/// <param name="rootElement"></param>
		private void AddDynamicNodes(XmlElement rootElement)
		{
			// Add some football teams
			XmlElement teams = AddDynamicChildElement(rootElement, "", "Football Teams", "List of football teams created dynamically");
			AddDynamicChildElement(teams, "~/teams.aspx?name=Watford", "Watford", "Watford's team details");
			AddDynamicChildElement(teams, "~/teams.aspx?name=Reading", "Reading", "Reading's team details");
			AddDynamicChildElement(teams, "~/teams.aspx?name=Liverpool", "Liverpool", "Liverpool's team details");

			XmlElement sheffield = AddDynamicChildElement(teams, "", "Sheffield", "There is more than one team in Sheffield");
			AddDynamicChildElement(sheffield, "~/teams.aspx?name=SheffieldUnited", "Sheffield United", "Sheffield United's team details");
			AddDynamicChildElement(sheffield, "~/teams.aspx?name=SheffieldWednesday", "Sheffield Wednesday", "Sheffield Wednesday's team details");

			XmlElement manchester = AddDynamicChildElement(teams, "", "Manchester", "There is more than one team in Manchester");
			AddDynamicChildElement(manchester, "~/teams.aspx?name=ManchesterUnited", "Manchester United", "Manchester United's team details");
			AddDynamicChildElement(manchester, "~/teams.aspx?name=ManchesterCity", "Manchester City", "Manchester City's team details");
		}

		private static XmlElement AddDynamicChildElement(XmlElement parentElement, String url, String title, String description)
		{
			// Create new element from the parameters
			XmlElement childElement = parentElement.OwnerDocument.CreateElement(SiteMapNodeName);
			childElement.SetAttribute("url", url);
			childElement.SetAttribute("title", title);
			childElement.SetAttribute("description", description);
			
			// Add it to the parent
			parentElement.AppendChild(childElement);
			return childElement;
		}

		private SiteMapNode GetSiteMapNodeFromElement(XmlElement rootElement)
		{
			SiteMapNode newSiteMapNode;
			String url = rootElement.GetAttribute("url");
			String title = rootElement.GetAttribute("title");
			String description = rootElement.GetAttribute("description");

			// The key needs to be unique, so hash the url and title.
			newSiteMapNode = new SiteMapNode(this,
				(url + title).GetHashCode().ToString(), url, title, description);

			return newSiteMapNode;
		}

		protected override SiteMapNode GetRootNodeCore()
		{
			return RootNode;
		}

		// Empty out the existing items.
		protected override void Clear()
		{
			lock (this)
			{
				_rootNode = null;
				base.Clear();
			}
		}
	}
}