Add selected features only mode to QgsVectorLayer::getValues

and getDoubleValues

Author: nyalldawson

python/core/qgsvectorlayer.sip

@@ -1136,21 +1136,23 @@ class QgsVectorLayer : QgsMapLayer
     /** Fetches all values from a specified field name or expression.
      * @param fieldOrExpression field name or an expression string
      * @param ok will be set to false if field or expression is invalid, otherwise true
+     * @param selectedOnly set to true to get values from selected features only
      * @returns list of fetched values
      * @note added in QGIS 2.9
      * @see getDoubleValues
      */
-    QList< QVariant > getValues( const QString &fieldOrExpression, bool &ok );
+    QList< QVariant > getValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false );
 
     /** Fetches all double values from a specified field name or expression. Null values or
      * invalid expression results are skipped.
      * @param fieldOrExpression field name or an expression string evaluating to a double value
      * @param ok will be set to false if field or expression is invalid, otherwise true
+     * @param selectedOnly set to true to get values from selected features only
      * @returns list of fetched values
      * @note added in QGIS 2.9
      * @see getValues
      */
-    QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok );
+    QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false );
 
     /** Set the blending mode used for rendering each feature */
     void setFeatureBlendMode( const QPainter::CompositionMode &blendMode );

src/core/qgsvectorlayer.cpp

@@ -3154,7 +3154,7 @@ QVariant QgsVectorLayer::maximumValue( int index )
   return QVariant();
 }
 
-QList<QVariant> QgsVectorLayer::getValues( const QString &fieldOrExpression, bool& ok )
+QList<QVariant> QgsVectorLayer::getValues( const QString &fieldOrExpression, bool& ok, bool selectedOnly )
 {
   QList<QVariant> values;
 
@@ -3179,11 +3179,21 @@ QList<QVariant> QgsVectorLayer::getValues( const QString &fieldOrExpression, boo
   else
     lst = expression->referencedColumns();
 
-  QgsFeatureIterator fit = getFeatures( QgsFeatureRequest()
-                                        .setFlags(( expression && expression->needsGeometry() ) ?
-                                                  QgsFeatureRequest::NoFlags :
-                                                  QgsFeatureRequest::NoGeometry )
-                                        .setSubsetOfAttributes( lst, pendingFields() ) );
+  QgsFeatureRequest request = QgsFeatureRequest()
+                              .setFlags(( expression && expression->needsGeometry() ) ?
+                                        QgsFeatureRequest::NoFlags :
+                                        QgsFeatureRequest::NoGeometry )
+                              .setSubsetOfAttributes( lst, pendingFields() );
+
+  QgsFeatureIterator fit;
+  if ( !selectedOnly )
+  {
+    fit = getFeatures( request );
+  }
+  else
+  {
+    fit = selectedFeaturesIterator( request );
+  }
 
   // create list of non-null attribute values
   while ( fit.nextFeature( f ) )
@@ -3195,11 +3205,11 @@ QList<QVariant> QgsVectorLayer::getValues( const QString &fieldOrExpression, boo
   return values;
 }
 
-QList<double> QgsVectorLayer::getDoubleValues( const QString &fieldOrExpression, bool& ok )
+QList<double> QgsVectorLayer::getDoubleValues( const QString &fieldOrExpression, bool& ok, bool selectedOnly )
 {
   QList<double> values;
 
-  QList<QVariant> variantValues = getValues( fieldOrExpression, ok );
+  QList<QVariant> variantValues = getValues( fieldOrExpression, ok, selectedOnly );
   if ( !ok )
     return values;
 

src/core/qgsvectorlayer.h

@@ -1501,21 +1501,23 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
     /** Fetches all values from a specified field name or expression.
      * @param fieldOrExpression field name or an expression string
      * @param ok will be set to false if field or expression is invalid, otherwise true
+     * @param selectedOnly set to true to get values from selected features only
      * @returns list of fetched values
      * @note added in QGIS 2.9
      * @see getDoubleValues
      */
-    QList< QVariant > getValues( const QString &fieldOrExpression, bool &ok );
+    QList< QVariant > getValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false );
 
     /** Fetches all double values from a specified field name or expression. Null values or
      * invalid expression results are skipped.
      * @param fieldOrExpression field name or an expression string evaluating to a double value
      * @param ok will be set to false if field or expression is invalid, otherwise true
+     * @param selectedOnly set to true to get values from selected features only
      * @returns list of fetched values
      * @note added in QGIS 2.9
      * @see getValues
      */
-    QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok );
+    QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false );
 
     /** Set the blending mode used for rendering each feature */
     void setFeatureBlendMode( const QPainter::CompositionMode &blendMode );

tests/src/core/testqgsvectorlayer.cpp

@@ -208,6 +208,11 @@ class TestQgsVectorLayer : public QObject
       f4.setAttribute( "col1", QVariant() );
       layer->dataProvider()->addFeatures( QgsFeatureList() << f1 << f2 << f3 << f4 );
 
+      //make a selection
+      QgsFeatureIds ids;
+      ids << f2.id() << f3.id();
+      layer->setSelectedFeatures( ids );
+
       bool ok;
       QList<QVariant> varList = layer->getValues( "col1", ok );
       QVERIFY( ok );
@@ -217,13 +222,27 @@ class TestQgsVectorLayer : public QObject
       QCOMPARE( varList.at( 2 ), QVariant( 3 ) );
       QCOMPARE( varList.at( 3 ), QVariant() );
 
+      //check with selected features
+      varList = layer->getValues( "col1", ok, true );
+      QVERIFY( ok );
+      QCOMPARE( varList.length(), 2 );
+      QCOMPARE( varList.at( 0 ), QVariant( 2 ) );
+      QCOMPARE( varList.at( 1 ), QVariant( 3 ) );
+
       QList<double> doubleList = layer->getDoubleValues( "col1", ok );
       QVERIFY( ok );
       QCOMPARE( doubleList.length(), 3 );
       QCOMPARE( doubleList.at( 0 ), 1.0 );
       QCOMPARE( doubleList.at( 1 ), 2.0 );
       QCOMPARE( doubleList.at( 2 ), 3.0 );
 
+      //check with selected features
+      doubleList = layer->getDoubleValues( "col1", ok, true );
+      QVERIFY( ok );
+      QCOMPARE( doubleList.length(), 2 );
+      QCOMPARE( doubleList.at( 0 ), 2.0 );
+      QCOMPARE( doubleList.at( 1 ), 3.0 );
+
       QList<QVariant> expVarList = layer->getValues( "tostring(col1) || ' '", ok );
       QVERIFY( ok );
       QCOMPARE( expVarList.length(), 4 );