Declarative QueryString Parameter Binding

using System;

namespace piers7.Web.Controls
{
	/// <summary>
	/// A <see cref="WebParameterAttribute"/> that's specifically bound to the
	/// a parameter in the query string (Request.QueryString collection)
	/// </summary>
	[AttributeUsage(AttributeTargets.Field | AttributeTargets.Property, AllowMultiple=false, Inherited=true)]
	public sealed class QueryParameterAttribute : WebParameterAttribute
	{
		#region Constructors
		/// <summary>
		/// Creates a new QueryParameterAttribute to load a field from an identically-named
		/// parameter in the QueryString collection, if it exists.
		/// The parameter has no default value, and is not required
		/// </summary>
		public QueryParameterAttribute() {
		}

		/// <summary>
		/// Creates a new QueryParameterAttribute to load a field from the given parameter
		/// in the QueryString collection, if it exists.
		/// The parameter has no default value, and is not required
		/// </summary>
		/// <param name="paramName">The key of a parameter in the QueryString collections</param>
		public QueryParameterAttribute(string paramName) : base(paramName) {
		}
		#endregion
		
		/// <summary>
		/// Retrieves an item from the QueryString by key
		/// </summary>
		protected override string GetValue(string paramName, System.Web.HttpRequest request)
		{
			return request.QueryString[paramName];
		}
	}
}