Template Based Multiple Control Validator

using System;
using System.ComponentModel;
using System.Security.Permissions;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using ValidationAggregator;

namespace ValidationAggregator
{
	[
		AspNetHostingPermission(SecurityAction.Demand,
			Level = AspNetHostingPermissionLevel.Minimal),
		AspNetHostingPermission(SecurityAction.InheritanceDemand,
			Level = AspNetHostingPermissionLevel.Minimal),
		Designer(typeof(ValidatorDesigner)),
		DefaultProperty("ControlToValidate"),
		ToolboxData("<{0}:Validator runat=\"server\"></{0}:Validator>")
	]
	public class Validator : WebControl
	{
		#region Fields

		private string _controlToValidate;
		private string _templateId;
		private string _label;
		private string _validationGroup;

		#endregion

		#region Properties

		[
			Category("Behavior"),
			DefaultValue(""),
			Description("")
		]
		public string ControlToValidate
		{
			get { return _controlToValidate; }
			set { _controlToValidate = value; }
		}

		[
			Category("Behavior"),
			DefaultValue(""),
			Description("")
		]
		public string TemplateId
		{
			get { return _templateId; }
			set { _templateId = value; }
		}

		[
			Category("Behavior"),
			DefaultValue(""),
			Description("")
		]
		public string Label
		{
			get { return _label; }
			set { _label = value; }
		}

		[
			Category("Behavior"),
			DefaultValue(""),
			Description("Override Template Validation Group")
		]
		public string ValidationGroup
		{
			get { return _validationGroup; }
			set { _validationGroup = value; }
		}

		#endregion

		protected override void CreateChildControls()
		{
			Controls.Clear();
			// Search for ValidationTemplate.
			ValidationTemplate t = SearchValidationTemplate();

			if (t == null)
				throw new Exception(string.Format("Could not find ValidationTemplate \"{0}\" specified in control \"{1}\"",
				                                  _templateId, ID));

			Controls.Add(t.GetValidators(new ControlDesc(_controlToValidate, _label), _validationGroup ?? ""));
		}

		public override ControlCollection Controls
		{
			get
			{
				EnsureChildControls();
				return base.Controls;
			}
		}

		protected override void Render(HtmlTextWriter writer)
		{
			EnsureChildControls();
			Controls[0].RenderControl(writer);
		}

		private ValidationTemplate SearchValidationTemplate()
		{
			Control container = NamingContainer;
			ValidationTemplate vt;

			do
			{
				vt = (ValidationTemplate) container.FindControl(_templateId);
				container = container.NamingContainer;

			} while (vt == null && container != null);

			return vt;
		}
	}
}