private void AddSort(LambdaExpression lambda, bool isStarting, bool ascending) { var body = lambda.Body as MemberExpression; if (body == null) { throw new NotSupportedException($"The expression {lambda} cannot be used in an Order clause"); } if (isStarting) { if (_optionalSortOrderHandle == null) { _optionalSortOrderHandle = _realm.MakeSortOrderForTable(_retType); } else { var badCall = ascending ? "By" : "ByDescending"; throw new NotSupportedException($"You can only use one OrderBy or OrderByDescending clause, subsequent sort conditions should be Then{badCall}"); } } var sortColName = body.Member.Name; NativeSortOrder.add_sort_clause(_optionalSortOrderHandle, sortColName, (IntPtr)sortColName.Length, ascending ? (IntPtr)1 : IntPtr.Zero); }