How to query all rows from a joined table?

Question

We tried to query all rows from a feature layer having a joined table and obtain all row values. When we are using the IDisplayTable::GetFieldDescription method all fields (also the joined fields) are returned, but when we are iterating through the RowCursor returned by IDisplayTable::Search only the values of the "origin table" are returned any access using a field index targetting a field from the joined table by Row::GetValue(fieldIndex) leads to a null reference.

Is this a known issue or do we need to downcast from FeatureLayer/StandaloneTable, or just access the row values using a different approach?

Thanks in advance.

BeverlyPham · Answer

Hi Wolf,

Would your query sample above also work for querying geodatabase tables? If not, how would you modify it? Thanks!

OSINT_ENGINEER · Answer

Finally we solved the issue. We implemented a kind of wrapper before accessing the underlying RowCursor and this custom implementation did not handled the GetTableDefinition exception correctly when the layer or standalone table is having a join. Sometimes it is really helpful by just letting someone know which things are not related to the problem.

Thank you so much for narrowing this down.

Wolf · Answer

Hi Jan, I just tried this using release 2.6 and it is working for me. In my test I have a feature layer that is joined to a table (both the feature layer and the table are in the TOC). I retrieve the feature layer for the query from the map using: var featureLayer = MapView.Active.Map.Layers.OfType<FeatureLayer>().Where (l => l.Name.Equals (...));‍ In my sample I only query the selected features, however, I see all values including the values of the joined table: QueryFilter qf = new QueryFilter() { ObjectIDs = featureLayer.GetSelection().GetObjectIDs() }; using (var rowCursor = featureLayer.Search(qf)) { while (rowCursor.MoveNext()) { using (var anyRow = rowCursor.Current) { foreach (var fld in anyRow.GetFields().Where(fld => fld.FieldType != FieldType.Geometry)) { // includes all 'joined' field names var fieldName = fld.Name; // fld.AliasName } foreach (var fld in anyRow.GetFields().Where(fld => fld.FieldType != FieldType.Geometry)) { // get all field values var fieldValue = (anyRow[fld.Name] == null) ? string.Empty : anyRow[fld.Name].ToString(); } } } } ‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ SebastianBosbach_0-1655193097490.png