I am attempting to perform a table join from a plug-in/outside of the built-in Python console. This is QGIS 3.16.1 and Python 3.7. I want to join two vector point layers, which have all points in exactly the same places. This is my code for the join:
# Create layers for output files
vectorpoint_filled_one = QgsVectorLayer(outputfile, '', 'ogr')
vectorpoint_filled_two = QgsVectorLayer(outputfile_two, 'final', 'ogr')
# Join tables
join_info = QgsVectorLayerJoinInfo()
join_info.setJoinLayer(vectorpoint_filled_one)
join_info.setJoinFieldName('field1')
join_info.setTargetFieldName('field1')
join_info.setUsingMemoryCache(True)
join_info.setJoinFieldNamesBlockList(['geom_X', 'geom_Y'])
vectorpoint_filled_two.addJoin(join_info)
# add to map canvas
QgsProject.instance().addMapLayer(vectorpoint_filled_two) #loads version from before table join
For some reason, the loaded map is vectorpoint_filled_two before the table join. However, when I also load vectorpoint_filled_one, the vectorpoint_filled_two is loaded (correctly) after the table join:
# Create layers for output files
vectorpoint_filled_one = QgsVectorLayer(outputfile, '', 'ogr')
vectorpoint_filled_two = QgsVectorLayer(outputfile_two, 'final', 'ogr')
# Join tables - add if statement to skip for no vector layers or no raster layers
join_info = QgsVectorLayerJoinInfo()
join_info.setJoinLayer(vectorpoint_filled_one)
join_info.setJoinFieldName('field1')
join_info.setTargetFieldName('field1')
join_info.setUsingMemoryCache(True)
join_info.setJoinFieldNamesBlockList(['geom_X', 'geom_Y'])
vectorpoint_filled_two.addJoin(join_info)
# add to map canvas
QgsProject.instance().addMapLayer(vectorpoint_filled_one)
QgsProject.instance().addMapLayer(vectorpoint_filled_two) #now loads correctly
This works, but I don't want to load vectorpoint_filled_one, as it is otherwise useless. I have tried various manners of reloading and updating vectorpoint_filled_two after the table join (startEditing() + commitChanges(), reload()), but it keeps loading the older version. I have also tried removing vectorpoint_filled_one after vectorpoint_filled_two is added to the map, but this will also result in the join missing from the loaded layer. Since the second version does work and addJoin returns True, I know the table join and previous code creating the layers are correct.
How do I load the correct version of vectorpoint_filled_two without also loading the other layer?
