[GRASS] fixed new feature attributes update

Author: blazek

src/providers/grass/qgsgrassprovider.cpp

@@ -1258,7 +1258,8 @@ void QgsGrassProvider::onFeatureAdded( QgsFeatureId fid )
       // resetting fid probably is not possible because it is stored in undo commands and used in buffer maps
 
       // It may be that user manualy entered cat value
-      const QgsFeature &feature = mEditBuffer->addedFeatures()[fid];
+      QgsFeatureMap& addedFeatures = const_cast<QgsFeatureMap&>( mEditBuffer->addedFeatures() );
+      QgsFeature& feature = addedFeatures[fid];
       int catIndex = feature.fields()->indexFromName( mLayer->keyColumnName() );
       if ( catIndex != -1 )
       {
@@ -1298,7 +1299,6 @@ void QgsGrassProvider::onFeatureAdded( QgsFeatureId fid )
         mLayer->updateAttributes( newCat, feature, error ); // also updates feature by existing non null attributes
 
         // There may be other new features with the same cat which we have to update
-        QgsFeatureMap& addedFeatures = const_cast<QgsFeatureMap&>( mEditBuffer->addedFeatures() );
         Q_FOREACH ( QgsFeatureId addedFid, addedFeatures.keys() )
         {
           if ( addedFid == fid )

src/providers/grass/qgsgrassvectormaplayer.cpp

@@ -902,7 +902,7 @@ void QgsGrassVectorMapLayer::reinsertAttributes( int cat, QString &error )
   }
 }
 
-void QgsGrassVectorMapLayer::updateAttributes( int cat, const QgsFeature &feature, QString &error, bool nullValues )
+void QgsGrassVectorMapLayer::updateAttributes( int cat, QgsFeature &feature, QString &error, bool nullValues )
 {
   QgsDebugMsg( QString( "mField = %1 cat = %2" ).arg( mField ).arg( cat ) );
 
@@ -936,7 +936,7 @@ void QgsGrassVectorMapLayer::updateAttributes( int cat, const QgsFeature &featur
       // update feature null values by existing values
       if ( cacheIndex != -1 )
       {
-        feature.attributes()[i] = mAttributes[cat][cacheIndex];
+        feature.setAttribute( i, mAttributes[cat][cacheIndex] );
       }
       continue;
     }

src/providers/grass/qgsgrassvectormaplayer.h

@@ -120,7 +120,7 @@ class GRASS_LIB_EXPORT QgsGrassVectorMapLayer : public QObject
      *  @param cat
      *  @param nullValues override all values, if false, only non empty values are used for update
      */
-    void updateAttributes( int cat, const QgsFeature &feature, QString &error, bool nullValues = false );
+    void updateAttributes( int cat, QgsFeature &feature, QString &error, bool nullValues = false );
 
     /** Delete attributes from the table
      *   @param cat