public EntitySQLSortItem(string fieldName, string aggregationPattern, EntitySQLSortDirection direction)
            : base(fieldName, aggregationPattern)
        {
            if (direction == null)
            {
                throw new ArgumentNullException("direction");
            }

            this.Direction = direction;
        }
 public EntitySQLSortItem(string fieldName, EntitySQLSortDirection direction)
     : this(fieldName, null, direction)
 {
 }