[layouts] Fix inefficient filtering in attribute tables

Set the expression filter on the request itself, rather than looping through all features and testing on the filter. This allows providers to hand off the filtering to the underlying datasource, and utilise indices/etc where available. Fixes #20908
qgis · Jan 4, 2019 · e3c1d18 · e3c1d18
1 parent 899dcbf
commit e3c1d18
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/src/core/layout/qgslayoutitemattributetable.cpp b/src/core/layout/qgslayoutitemattributetable.cpp
@@ -399,6 +399,8 @@ bool QgsLayoutItemAttributeTable::getTableContents( QgsLayoutTableContents &cont
   QgsExpressionContext context = createExpressionContext();
   context.setFields( layer->fields() );
 
+  QgsFeatureRequest req;
+
   //prepare filter expression
   std::unique_ptr<QgsExpression> filterExpression;
   bool activeFilter = false;
@@ -408,6 +410,7 @@ bool QgsLayoutItemAttributeTable::getTableContents( QgsLayoutTableContents &cont
     if ( !filterExpression->hasParserError() )
     {
       activeFilter = true;
+      req.setFilterExpression( mFeatureFilter );
     }
   }
 
@@ -431,8 +434,6 @@ bool QgsLayoutItemAttributeTable::getTableContents( QgsLayoutTableContents &cont
     }
   }
 
-  QgsFeatureRequest req;
-
   if ( mSource == QgsLayoutItemAttributeTable::RelationChildren )
   {
     QgsRelation relation = mLayout->project()->relationManager()->relation( mRelationId );