Extending linq order by method.

GenericEvaulatingOrderBy.cs

namespace Common.Extension
{
  using System.Linq;
	using System.Linq.Expressions;

	public static class GenericEvaulatingOrderBy
	{
		private static IOrderedQueryable<T> OrderingHelper<T>(IQueryable<T> source, string propertyName, bool descending, bool anotherLevel)
		{
			var param = Expression.Parameter(typeof(T), "p");
			var property = Expression.PropertyOrField(param, propertyName);
			var sort = Expression.Lambda(property, param);

			var call = Expression.Call(
				typeof(Queryable),
				(!anotherLevel ? "OrderBy" : "ThenBy") + (descending ? "Descending" : string.Empty),
				new[] { typeof(T), property.Type },
				source.Expression,
				Expression.Quote(sort));

			return (IOrderedQueryable<T>)source.Provider.CreateQuery<T>(call);
		}

		public static IOrderedQueryable<T> OrderBy<T>(this IQueryable<T> source, string propertyName)
		{
			return OrderingHelper(source, propertyName, false, false);
		}

		public static IOrderedQueryable<T> OrderBy<T>(this IQueryable<T> source, string propertyName, bool descending)
		{
			return OrderingHelper(source, propertyName, descending, false);
		}

		public static IOrderedQueryable<T> ThenBy<T>(this IOrderedQueryable<T> source, string propertyName)
		{
			return OrderingHelper(source, propertyName, false, true);
		}

		public static IOrderedQueryable<T> ThenBy<T>(this IOrderedQueryable<T> source, string propertyName, bool descending)
		{
			return OrderingHelper(source, propertyName, descending, true);
		}
	}
}