QGIS » QGIS Application

I have a postgis layer with several styles saved in table public.layer_styles.
All styles have useasdefault set to false (these styles only makes sense within some projects, should not be used as default styles).

Obtained results¶

When I open the layer without any project, one of the styles is applied, in particular the one with update_time more recent.

Expected results¶

When I open the layer without any project, no style is applied

Discussion¶

The exact query that finds the default style is in ~qgis/src/providers/postgres/qgspostgresprovider.cpp, line 3464

  QString selectQmlQuery = QString( "SELECT styleQML" 
                                    " FROM layer_styles" 
                                    " WHERE f_table_catalog=%1" 
                                    " AND f_table_schema=%2" 
                                    " AND f_table_name=%3" 
                                    " AND f_geometry_column=%4" 
                                    " ORDER BY CASE WHEN useAsDefault THEN 1 ELSE 2 END" 
                                    ",update_time DESC LIMIT 1" )

In my opinion rows with useasdefault set to false should be completely filtered out by the query.

If all styles have useasdefault set to false, current query retrieves the most recent style while I think that no rows should be retrieved in this case and a "random color" style be applied.

Thus I propose to change the query to:

  QString selectQmlQuery = QString( "SELECT styleQML" 
                                    " FROM layer_styles" 
                                    " WHERE f_table_catalog=%1" 
                                    " AND f_table_schema=%2" 
                                    " AND f_table_name=%3" 
                                    " AND f_geometry_column=%4" 
                                    " WHERE useAsDefault" 
                                    " ORDER BY update_time DESC LIMIT 1" )