Extending the Label Control

using System;
using System.Data;
using System.Web;
using System.Web.Caching;

namespace MyControls
{
	/// <summary>
	/// Class for returning resource strings from an XML file
	/// </summary>
	public class XMLResource
	{
		/// <summary> 
		/// Get a DataSet with resource strings
		/// </summary>
		/// <returns>DataSet with resource strings</returns>
		private DataSet GetResourceDS()
		{
			//Try to get the DataSet from the Cache first
			//Note that this one bombs at design time, (we have no HttpContext)
			//but this exception is caught in the custom control
			DataSet ds = (DataSet)HttpContext.Current.Cache[HttpContext.Current.Request.CurrentExecutionFilePath];
			if(ds == null)
			{
				//no DataSet in the Cache, get a new one and store it in the cache
				//get the text-id from the resource file for our web-page
				ds = new DataSet("resourceStrings");

				//build the name of the xml file from the name of the web page we're sitting in
				String fileName = HttpContext.Current.Request.CurrentExecutionFilePath;
				fileName = fileName.Substring(0, fileName.LastIndexOf(".")) + ".xml";

				try
				{
					//read ds from the xml file
					ds.ReadXml(HttpContext.Current.Server.MapPath(fileName));
				}
				catch (System.IO.FileNotFoundException)
				{
					//xml file not found, we will return the empty DataSet
				}
				//put in Cache with dependency to the xml file
				HttpContext.Current.Cache.Insert(HttpContext.Current.Request.CurrentExecutionFilePath,
					ds, new CacheDependency(HttpContext.Current.Server.MapPath(fileName)));
			}

			return ds;
		}

		/// <summary> 
		/// Get the value from the XML resource
		/// </summary>
		/// <param name="key">The ID of the value to get</param>
		/// <param name="defaultValue">The default value to return if the key is not found</param>
		public String GetValueFromKey(String key, String defaultValue)
		{
			DataSet ds = GetResourceDS();

			//filter out everything except our resource string in a dataview
			DataView dv = ds.Tables[0].DefaultView;
			dv.RowFilter = "key = '" + key + "'";
			if(dv.Count > 0)	//key found, show the value
				return dv[0]["value"].ToString();
			else	//key not found return default value
				return defaultValue;
		}
	}
}