Add option to get null count from QgsVectorLayer::getDoubleValues

qgis · May 22, 2015 · 1078daf · 1078daf
1 parent 0aedbca
commit 1078daf
Show file tree

Hide file tree

Showing 4 changed files with 20 additions and 6 deletions.
diff --git a/python/core/qgsvectorlayer.sip b/python/core/qgsvectorlayer.sip
@@ -1148,11 +1148,12 @@ class QgsVectorLayer : QgsMapLayer
      * @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
+     * @param nullCount optional pointer to integer to store number of null values encountered in
      * @returns list of fetched values
      * @note added in QGIS 2.9
      * @see getValues
      */
-    QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false );
+    QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false, int* nullCount = 0 );
 
     /** Set the blending mode used for rendering each feature */
     void setFeatureBlendMode( const QPainter::CompositionMode &blendMode );

diff --git a/src/core/qgsvectorlayer.cpp b/src/core/qgsvectorlayer.cpp
@@ -3205,10 +3205,13 @@ QList<QVariant> QgsVectorLayer::getValues( const QString &fieldOrExpression, boo
   return values;
 }
 
-QList<double> QgsVectorLayer::getDoubleValues( const QString &fieldOrExpression, bool& ok, bool selectedOnly )
+QList<double> QgsVectorLayer::getDoubleValues( const QString &fieldOrExpression, bool& ok, bool selectedOnly, int* nullCount )
 {
   QList<double> values;
 
+  if ( nullCount )
+    *nullCount = 0;
+
   QList<QVariant> variantValues = getValues( fieldOrExpression, ok, selectedOnly );
   if ( !ok )
     return values;
@@ -3219,6 +3222,11 @@ QList<double> QgsVectorLayer::getDoubleValues( const QString &fieldOrExpression,
     double val = value.toDouble( &convertOk );
     if ( convertOk )
       values << val;
+    else if ( value.isNull() )
+    {
+      if ( nullCount )
+        *nullCount += 1;
+    }
   }
   ok = true;
   return values;

diff --git a/src/core/qgsvectorlayer.h b/src/core/qgsvectorlayer.h
@@ -1514,11 +1514,12 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
      * @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
+     * @param nullCount optional pointer to integer to store number of null values encountered in
      * @returns list of fetched values
      * @note added in QGIS 2.9
      * @see getValues
      */
-    QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false );
+    QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false, int* nullCount = 0 );
 
     /** Set the blending mode used for rendering each feature */
     void setFeatureBlendMode( const QPainter::CompositionMode &blendMode );

diff --git a/tests/src/core/testqgsvectorlayer.cpp b/tests/src/core/testqgsvectorlayer.cpp
@@ -229,19 +229,22 @@ class TestQgsVectorLayer : public QObject
       QCOMPARE( varList.at( 0 ), QVariant( 2 ) );
       QCOMPARE( varList.at( 1 ), QVariant( 3 ) );
 
-      QList<double> doubleList = layer->getDoubleValues( "col1", ok );
+      int nulls = 0;
+      QList<double> doubleList = layer->getDoubleValues( "col1", ok, false, &nulls );
       QVERIFY( ok );
       QCOMPARE( doubleList.length(), 3 );
       QCOMPARE( doubleList.at( 0 ), 1.0 );
       QCOMPARE( doubleList.at( 1 ), 2.0 );
       QCOMPARE( doubleList.at( 2 ), 3.0 );
+      QCOMPARE( nulls, 1 );
 
       //check with selected features
-      doubleList = layer->getDoubleValues( "col1", ok, true );
+      doubleList = layer->getDoubleValues( "col1", ok, true, &nulls );
       QVERIFY( ok );
       QCOMPARE( doubleList.length(), 2 );
       QCOMPARE( doubleList.at( 0 ), 2.0 );
       QCOMPARE( doubleList.at( 1 ), 3.0 );
+      QCOMPARE( nulls, 0 );
 
       QList<QVariant> expVarList = layer->getValues( "tostring(col1) || ' '", ok );
       QVERIFY( ok );
@@ -251,12 +254,13 @@ class TestQgsVectorLayer : public QObject
       QCOMPARE( expVarList.at( 2 ).toString(), QString( "3 " ) );
       QCOMPARE( expVarList.at( 3 ), QVariant() );
 
-      QList<double> expDoubleList = layer->getDoubleValues( "col1 * 2", ok );
+      QList<double> expDoubleList = layer->getDoubleValues( "col1 * 2", ok, false, &nulls );
       QVERIFY( ok );
       QCOMPARE( expDoubleList.length(), 3 );
       QCOMPARE( expDoubleList.at( 0 ), 2.0 );
       QCOMPARE( expDoubleList.at( 1 ), 4.0 );
       QCOMPARE( expDoubleList.at( 2 ), 6.0 );
+      QCOMPARE( nulls, 1 );
 
       delete layer;
     }