[dualview] Default preview text shows also up for NULL values

qgis · Sep 2, 2013 · a105987 · a105987
1 parent a6b52b7
commit a105987
Showing 1 changed file with 19 additions and 7 deletions.
diff --git a/src/gui/attributetable/qgsdualview.cpp b/src/gui/attributetable/qgsdualview.cpp
@@ -80,13 +80,19 @@ void QgsDualView::columnBoxInit()
   // load fields
   QList<QgsField> fields = mLayerCache->layer()->pendingFields().toList();
 
+  QString defaultField;
+
   // default expression: saved value
   QString displayExpression = mLayerCache->layer()->displayExpression();
 
   // if no display expression is saved: use display field instead
   if ( displayExpression == "" )
   {
-    displayExpression = mLayerCache->layer()->displayField();
+    if ( mLayerCache->layer()->displayField() != "" )
+    {
+      defaultField = mLayerCache->layer()->displayField();
+      displayExpression = QString( "COALESCE(\"%1\", '<NULL>')" ).arg( defaultField );
+    }
   }
 
   // if neither diaplay expression nor display field is saved...
@@ -96,31 +102,37 @@ void QgsDualView::columnBoxInit()
 
     if ( pkAttrs.size() > 0 )
     {
+      if ( pkAttrs.size() == 1 )
+        defaultField = pkAttrs.at( 0 );
+
       // ... If there are primary key(s) defined
       QStringList pkFields;
 
-      foreach ( int attr, pkAttrs )
+      Q_FOREACH( int attr, pkAttrs )
       {
-        pkFields.append( "\"" + fields[attr].name() + "\"" );
+        pkFields.append( "COALESCE(\"" + fields[attr].name() + "\", '<NULL>')" );
       }
 
       displayExpression = pkFields.join( "||', '||" );
     }
     else if ( fields.size() > 0 )
     {
+      if ( fields.size() == 1 )
+        defaultField = fields.at( 0 ).name();
+
       // ... concat all fields
       QStringList fieldNames;
       foreach ( QgsField field, fields )
       {
-        fieldNames.append( "\"" + field.name() + "\"" );
+        fieldNames.append( "COALESCE(\"" + field.name() + "\", '<NULL>')" );
       }
 
       displayExpression = fieldNames.join( "||', '||" );
     }
     else
     {
       // ... there isn't really much to display
-      displayExpression = "[Please define preview text]";
+      displayExpression = "'[Please define preview text]'";
     }
   }
 
@@ -151,7 +163,7 @@ void QgsDualView::columnBoxInit()
       connect( previewAction, SIGNAL( triggered() ), mPreviewActionMapper, SLOT( map() ) );
       mPreviewColumnsMenu->addAction( previewAction );
 
-      if ( text == displayExpression )
+      if ( text == defaultField )
       {
         mFeatureListPreviewButton->setDefaultAction( previewAction );
       }
@@ -315,7 +327,7 @@ void QgsDualView::previewColumnChanged( QObject* action )
 
   if ( previewAction )
   {
-    if ( !mFeatureList->setDisplayExpression( previewAction->text() ) )
+    if ( !mFeatureList->setDisplayExpression( QString( "COALESCE( \"%1\", '<NULL>' )" ).arg( previewAction->text() ) ) )
     {
       QMessageBox::warning( this
                             , tr( "Could not set preview column" )