SortQueryableExtensions

    public static class SortQueryableExtensions
    {
        public static IQueryable<T> ApplySort<T>(this IQueryable<T> queryable, string sort)
        {
            if (queryable == null)
                throw new ArgumentNullException();

            if (string.IsNullOrWhiteSpace(sort))
                return queryable;

            string completeSortExpression = "";
            foreach (var sortOption in sort.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries))
            {
                if (sortOption.StartsWith("-"))
                {
                    completeSortExpression += sortOption.Remove(0, 1) + " descending,";
                }
                else
                {
                    completeSortExpression += sortOption + ",";
                }
            }

            if (!string.IsNullOrWhiteSpace(completeSortExpression))
            {
                queryable = 
                    queryable
                        .OrderBy(completeSortExpression.Remove(completeSortExpression.Count() - 1));
            }

            return queryable;
        }
    }