Hi, We are asked to work on subset filtering when a qgis layer has joined fields.
Currently, the filter feature has been disabled on a layer with joined fields to circumvent a bug (see http://hub.qgis.org/issues/3858 and http://hub.qgis.org/issues/3857). What if you want to implement filtering on a table with joined fields ? Filtering on fields of the primary table would be ok, assuming we find another way to circumvent the mentioned bug (propose to rename fields when saving to shapefiles ?). Filtering on fields from the joined tables (but not he primary) is a bit more problematic. We could imagine attributes to joins (within the joins tab of the property dialog) where users could define a where clause on joined tables. But the joining function would have to be modified in order for it to reject rows when rows of joined tables are null (correct?). For filtering on every possible combination of fields, including those from the primary table and joined tables, the best option would be to propose a filter expressiion based on QgsExpression. It means filtering would happen client-side, after data have been fetched from the different providers. It's convenient, but not very efficient. Comments, other ideas ? :) -- Hugo Mercier Oslandia _______________________________________________ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
