Saver attribute map handling (no insertion of additional entry if a column does not exist)

git-svn-id: http://svn.osgeo.org/qgis/trunk@15388 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: mhugent

src/providers/ogr/qgsogrprovider.cpp

@@ -1902,7 +1902,13 @@ void QgsOgrProvider::uniqueValues( int index, QList<QVariant> &uniqueValues, int
 
 QVariant QgsOgrProvider::minimumValue( int index )
 {
-  QgsField fld = mAttributeFields[index];
+  QgsFieldMap::const_iterator attIt = mAttributeFields.find( index );
+  if ( attIt == mAttributeFields.constEnd() )
+  {
+    return QVariant();
+  }
+  const QgsField& fld = attIt.value();
+
   QString theLayerName = OGR_FD_GetName( OGR_L_GetLayerDefn( ogrLayer ) );
 
   QString sql = QString( "SELECT MIN(%1) FROM %2" )
@@ -1936,7 +1942,13 @@ QVariant QgsOgrProvider::minimumValue( int index )
 
 QVariant QgsOgrProvider::maximumValue( int index )
 {
-  QgsField fld = mAttributeFields[index];
+  QgsFieldMap::const_iterator attIt = mAttributeFields.find( index );
+  if ( attIt == mAttributeFields.constEnd() )
+  {
+    return QVariant();
+  }
+  const QgsField& fld = mAttributeFields[index];
+
   QString theLayerName = OGR_FD_GetName( OGR_L_GetLayerDefn( ogrLayer ) );
 
   QString sql = QString( "SELECT MAX(%1) FROM %2" )