Update all attributes in a single transaction

Fixes #17869

src/core/qgsvectorlayer.cpp

@@ -2384,6 +2384,48 @@ bool QgsVectorLayer::changeAttributeValue( QgsFeatureId fid, int field, const QV
   return mEditBuffer->changeAttributeValue( fid, field, newValue, oldValue );
 }
 
+bool QgsVectorLayer::changeAttributeValues( QgsFeatureId fid, const QgsAttributeMap &newValues, const QgsAttributeMap &oldValues )
+{
+  bool result = true;
+
+  QgsAttributeMap newValidValues;
+  QgsAttributeMap oldValidValues;
+
+  QgsAttributeMap::const_iterator it;
+  for ( it = newValues.constBegin(); it != newValues.constEnd(); ++it )
+  {
+    const int field = it.key();
+    const QVariant newValue = it.value();
+    QVariant oldValue;
+
+    if ( oldValues.contains( field ) )
+      oldValue = oldValues[field];
+
+    switch ( fields().fieldOrigin( field ) )
+    {
+      case QgsFields::OriginProvider:
+      case QgsFields::OriginEdit:
+      case QgsFields::OriginExpression:
+      {
+        newValidValues[field] = newValue;
+        oldValidValues[field] = oldValue;
+        break;
+      }
+
+      case QgsFields::OriginJoin:
+      case QgsFields::OriginUnknown:
+        break;
+    }
+  }
+
+  if ( ! newValidValues.isEmpty() && mEditBuffer && mDataProvider )
+  {
+    result &= mEditBuffer->changeAttributeValues( fid, newValidValues, oldValidValues );
+  }
+
+  return result;
+}
+
 bool QgsVectorLayer::addAttribute( const QgsField &field )
 {
   if ( !mEditBuffer || !mDataProvider )

src/core/qgsvectorlayer.h

@@ -1347,6 +1347,39 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
      */
     bool changeAttributeValue( QgsFeatureId fid, int field, const QVariant &newValue, const QVariant &oldValue = QVariant() );
 
+    /**
+     * Changes attributes' values for a feature (but does not immediately
+     * commit the changes).
+     * The \a fid argument specifies the ID of the feature to be changed.
+     *
+     * The new values to be assigned to the fields are given by \a newValues.
+     *
+     * If a valid QVariant is specified for a field in \a oldValues, it will be
+     * used as the field value in the case of an undo operation corresponding
+     * to this attribute value change. If an invalid QVariant is used (the
+     * default behavior), then the feature's current value will be
+     * automatically retrieved and used. Note that this involves a feature
+     * request to the underlying data provider, so it is more efficient to
+     * explicitly pass an oldValue if it is already available.
+     *
+     * Returns true if feature's attributes was successfully changed.
+     *
+     * \note Calls to changeAttributeValues() are only valid for layers in
+     * which edits have been enabled by a call to startEditing(). Changes made
+     * to features using this method are not committed to the underlying data
+     * provider until a commitChanges() call is made. Any uncommitted changes
+     * can be discarded by calling rollBack().
+     *
+     * \see startEditing()
+     * \see commitChanges()
+     * \see changeGeometry()
+     * \see updateFeature()
+     * \see changeAttributeValue()
+     *
+     * \since QGIS 2.18
+     */
+    bool changeAttributeValues( QgsFeatureId fid, const QgsAttributeMap &newValues, const QgsAttributeMap &oldValues );
+
     /** Add an attribute field (but does not commit it)
      * returns true if the field was added
      */

src/core/qgsvectorlayereditbuffer.cpp

@@ -776,3 +776,22 @@ void QgsVectorLayerEditBuffer::updateLayerFields()
 {
   L->updateFields();
 }
+
+bool QgsVectorLayerEditBuffer::changeAttributeValues( QgsFeatureId fid, const QgsAttributeMap &newValues, const QgsAttributeMap &oldValues )
+{
+  bool success = true;
+  QgsAttributeMap::const_iterator it;
+  for ( it = newValues.constBegin() ; it != newValues.constEnd(); ++it )
+  {
+    const int field = it.key();
+    const QVariant newValue = it.value();
+    QVariant oldValue;
+
+    if ( oldValues.contains( field ) )
+      oldValue = oldValues[field];
+
+    success &= changeAttributeValue( fid, field, newValue, oldValue );
+  }
+
+  return success;
+}

src/core/qgsvectorlayereditbuffer.h

@@ -99,7 +99,12 @@ class CORE_EXPORT QgsVectorLayerEditBuffer : public QObject
     /** Stop editing and discard the edits */
     virtual void rollBack();
 
-
+    /**
+     * Changes values of attributes (but does not commit it).
+     * \returns true if attributes are well updated, false otherwise
+     * \since QGIS 2.18
+     */
+    virtual bool changeAttributeValues( QgsFeatureId fid, const QgsAttributeMap &newValues, const QgsAttributeMap &oldValues );
 
     /** New features which are not commited. */
     inline const QgsFeatureMap& addedFeatures() { return mAddedFeatures; }

src/core/qgsvectorlayereditpassthrough.cpp

@@ -109,6 +109,27 @@ bool QgsVectorLayerEditPassthrough::changeAttributeValue( QgsFeatureId fid, int
   return false;
 }
 
+bool QgsVectorLayerEditPassthrough::changeAttributeValues( QgsFeatureId fid, const QgsAttributeMap &newValues, const QgsAttributeMap &oldValues )
+{
+  Q_UNUSED( oldValues );
+  bool result = false;
+
+  QgsChangedAttributesMap attribMap;
+  attribMap.insert( fid, newValues );
+
+  if ( L->dataProvider()->changeAttributeValues( attribMap ) )
+  {
+    result = true;
+    QgsAttributeMap::const_iterator it;
+    for ( it = newValues.constBegin(); it != newValues.constEnd(); ++it )
+    {
+      emit attributeValueChanged( fid, it.key(), it.value() );
+    }
+  }
+
+  return result;
+}
+
 bool QgsVectorLayerEditPassthrough::addAttribute( const QgsField &field )
 {
   if ( L->dataProvider()->addAttributes( QList<QgsField>() << field ) )

src/core/qgsvectorlayereditpassthrough.h

@@ -34,6 +34,7 @@ class CORE_EXPORT QgsVectorLayerEditPassthrough : public QgsVectorLayerEditBuffe
     bool deleteFeatures( const QgsFeatureIds& fids ) override;
     bool changeGeometry( QgsFeatureId fid, QgsGeometry* geom ) override;
     bool changeAttributeValue( QgsFeatureId fid, int field, const QVariant &newValue, const QVariant &oldValue = QVariant() ) override;
+    bool changeAttributeValues( QgsFeatureId fid, const QgsAttributeMap &newValues, const QgsAttributeMap &oldValues ) override;
     bool addAttribute( const QgsField &field ) override;
     bool deleteAttribute( int attr ) override;
     bool renameAttribute( int attr, const QString& newName ) override;

src/gui/qgsattributeform.cpp

@@ -337,6 +337,9 @@ bool QgsAttributeForm::saveEdits()
       {
         mLayer->beginEditCommand( mEditCommandMessage );
 
+        QgsAttributeMap newValues;
+        QgsAttributeMap oldValues;
+
         int n = 0;
         for ( int i = 0; i < dst.count(); ++i )
         {
@@ -353,10 +356,14 @@ bool QgsAttributeForm::saveEdits()
           QgsDebugMsg( QString( "src:'%1' (type:%2, isNull:%3, isValid:%4)" )
                        .arg( src.at( i ).toString(), src.at( i ).typeName() ).arg( src.at( i ).isNull() ).arg( src.at( i ).isValid() ) );
 
-          success &= mLayer->changeAttributeValue( mFeature.id(), i, dst.at( i ), src.at( i ) );
+          newValues[i] = dst.at( i );
+          oldValues[i] = src.at( i );
+
           n++;
         }
 
+        success = mLayer->changeAttributeValues( mFeature.id(), newValues, oldValues );
+
         if ( success && n > 0 )
         {
           mLayer->endEditCommand();