public ReportBuilder(Page page, VwbQuery query) { _page = page; _query = query.Clone(); IEnumerable <string> immutableColKeys = ColumnFactory.ImmutableColumns.Select(i => i.Key()); if (_query.SortColumnKey != null && !_query.ColumnKeysInOrder.Contains(_query.SortColumnKey) && !immutableColKeys.Contains(_query.SortColumnKey)) { _query.SortColumnKey = null; } if (string.IsNullOrEmpty(_query.SortColumnKey)) { //if no sort defined, sort by article number _query.SortColumnKey = ColumnFactory.GetArticleNumberColumn().Key(); } }