More efficient field calculator iteration

nyalldawson · nyalldawson · commit 9f3b90775a7c · 2018-10-16T06:28:36.000+10:00
diff --git a/src/app/qgsattributetabledialog.cpp b/src/app/qgsattributetabledialog.cpp
@@ -536,6 +536,10 @@ void QgsAttributeTableDialog::runFieldCalculation( QgsVectorLayer *layer, const
 
   QgsField fld = layer->fields().at( fieldindex );
 
+  QSet< QString >referencedColumns = exp.referencedColumns();
+  referencedColumns.insert( fld.name() ); // need existing column value to store old attribute when changing field values
+  request.setSubsetOfAttributes( referencedColumns, layer->fields() );
+
   //go through all the features and change the new attributes
   QgsFeatureIterator fit = layer->getFeatures( request );
   QgsFeature feature;
diff --git a/src/app/qgsfieldcalculator.cpp b/src/app/qgsfieldcalculator.cpp
@@ -281,6 +281,9 @@ void QgsFieldCalculator::accept()
       emptyAttribute = QVariant( field.type() );
 
     QgsFeatureRequest req = QgsFeatureRequest().setFlags( useGeometry ? QgsFeatureRequest::NoFlags : QgsFeatureRequest::NoGeometry );
+    QSet< QString > referencedColumns = exp.referencedColumns();
+    referencedColumns.insert( field.name() ); // need existing column value to store old attribute when changing field values
+    req.setSubsetOfAttributes( referencedColumns, mVectorLayer->fields() );
     if ( mOnlyUpdateSelectedCheckBox->isChecked() )
     {
       req.setFilterFids( mVectorLayer->selectedFeatureIds() );

Original file line number	Diff line number	Diff line change
`@@ -281,6 +281,9 @@ void QgsFieldCalculator::accept()`
`281`	`281`	`emptyAttribute = QVariant( field.type() );`
`282`	`282`
`283`	`283`	`QgsFeatureRequest req = QgsFeatureRequest().setFlags( useGeometry ? QgsFeatureRequest::NoFlags : QgsFeatureRequest::NoGeometry );`
	`284`	`+ QSet< QString > referencedColumns = exp.referencedColumns();`
	`285`	`+ referencedColumns.insert( field.name() ); // need existing column value to store old attribute when changing field values`
	`286`	`+ req.setSubsetOfAttributes( referencedColumns, mVectorLayer->fields() );`
`284`	`287`	`if ( mOnlyUpdateSelectedCheckBox->isChecked() )`
`285`	`288`	`{`
`286`	`289`	`req.setFilterFids( mVectorLayer->selectedFeatureIds() );`