Fix logic in detecting whether attribute form widgets have changed

Since two null QVariants can be reported as not equal if they have different underlying types we need to ensure that we don't flag this situation as a changed value.
qgis · May 24, 2016 · 2fddc00 · 2fddc00
1 parent 38e0502
commit 2fddc00
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/src/gui/qgsattributeform.cpp b/src/gui/qgsattributeform.cpp
@@ -274,9 +274,14 @@ bool QgsAttributeForm::saveEdits()
       {
         QVariant dstVar = dst.at( eww->fieldIdx() );
         QVariant srcVar = eww->value();
+
         // need to check dstVar.isNull() != srcVar.isNull()
         // otherwise if dstVar=NULL and scrVar=0, then dstVar = srcVar
-        if (( dstVar != srcVar || dstVar.isNull() != srcVar.isNull() ) && srcVar.isValid() && !mLayer->editFormConfig()->readOnly( eww->fieldIdx() ) )
+        // be careful- sometimes two null qvariants will be reported as not equal!! (eg different types)
+        bool changed = ( dstVar != srcVar && !dstVar.isNull() && !srcVar.isNull() )
+                       || ( dstVar.isNull() != srcVar.isNull() );
+        if ( changed && srcVar.isValid()
+             && !mLayer->editFormConfig()->readOnly( eww->fieldIdx() ) )
         {
           dst[eww->fieldIdx()] = srcVar;