Use client side default values when creating new features

Sponsored by DB Fahrwegdienste GmbH

Author: nyalldawson

src/app/qgisapp.cpp

@@ -7380,6 +7380,11 @@ void QgisApp::editPaste( QgsMapLayer *destinationLayer )
     remap.insert( idx, dst );
   }
 
+  QgsExpressionContext context;
+  context << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope()
+  << QgsExpressionContextUtils::layerScope( pasteVectorLayer );
+
   int dstAttrCount = pasteVectorLayer->fields().count();
 
   QgsFeatureList::iterator featureIt = features.begin();
@@ -7391,8 +7396,18 @@ void QgisApp::editPaste( QgsMapLayer *destinationLayer )
     // pre-initialized with default values
     for ( int dst = 0; dst < dstAttr.count(); ++dst )
     {
-      QVariant defVal( pasteVectorLayer->dataProvider()->defaultValue( dst ) );
-      if ( !defVal.isNull() )
+      QVariant defVal;
+      if ( !pasteVectorLayer->defaultValueExpression( dst ).isEmpty() )
+      {
+        // client side default expression set - use this in preference to provider default
+        defVal = pasteVectorLayer->defaultValue( dst, *featureIt, &context );
+      }
+      else
+      {
+        defVal = pasteVectorLayer->dataProvider()->defaultValue( dst );
+      }
+
+      if ( defVal.isValid() && !defVal.isNull() )
       {
         dstAttr[ dst ] = defVal;
       }

src/app/qgsmergeattributesdialog.cpp

@@ -522,14 +522,21 @@ QgsAttributes QgsMergeAttributesDialog::mergedAttributes() const
     return QgsAttributes();
   }
 
+  QgsExpressionContext context;
+  context << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope()
+  << QgsExpressionContextUtils::layerScope( mVectorLayer );
+
   int widgetIndex = 0;
   QgsAttributes results( mFields.count() );
   for ( int fieldIdx = 0; fieldIdx < mFields.count(); ++fieldIdx )
   {
     if ( mHiddenAttributes.contains( fieldIdx ) )
     {
       //hidden attribute, set to default value
-      if ( mVectorLayer->dataProvider() )
+      if ( !mVectorLayer->defaultValueExpression( fieldIdx ).isEmpty() )
+        results[fieldIdx] = mVectorLayer->defaultValue( fieldIdx, mFeatureList.at( 0 ), &context );
+      else if ( mVectorLayer->dataProvider() )
         results[fieldIdx] = mVectorLayer->dataProvider()->defaultValue( fieldIdx );
       else
         results[fieldIdx] = QVariant();
@@ -551,6 +558,10 @@ QgsAttributes QgsMergeAttributesDialog::mergedAttributes() const
     {
       results[fieldIdx] = currentItem->data( Qt::DisplayRole );
     }
+    else if ( !mVectorLayer->defaultValueExpression( fieldIdx ).isEmpty() )
+    {
+      results[fieldIdx] = mVectorLayer->defaultValue( fieldIdx, mFeatureList.at( 0 ), &context );
+    }
     else if ( mVectorLayer->dataProvider() )
     {
       results[fieldIdx] = mVectorLayer->dataProvider()->defaultValue( fieldIdx );

src/core/qgsofflineediting.cpp

@@ -746,14 +746,12 @@ void QgsOfflineEditing::applyFeaturesAdded( QgsVectorLayer* offlineLayer, QgsVec
   QString sql = QString( "SELECT \"fid\" FROM 'log_added_features' WHERE \"layer_id\" = %1" ).arg( layerId );
   QList<int> newFeatureIds = sqlQueryInts( db, sql );
 
-  // get default value for each field
-  const QgsFields& remoteFlds = remoteLayer->fields();
-  QVector<QVariant> defaultValues( remoteFlds.count() );
-  for ( int i = 0; i < remoteFlds.count(); ++i )
-  {
-    if ( remoteFlds.fieldOrigin( i ) == QgsFields::OriginProvider )
-      defaultValues[i] = remoteLayer->dataProvider()->defaultValue( remoteFlds.fieldOriginIndex( i ) );
-  }
+  QgsFields remoteFlds = remoteLayer->fields();
+
+  QgsExpressionContext context;
+  context << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope()
+  << QgsExpressionContextUtils::layerScope( remoteLayer );
 
   // get new features from offline layer
   QgsFeatureList features;
@@ -789,8 +787,13 @@ void QgsOfflineEditing::applyFeaturesAdded( QgsVectorLayer* offlineLayer, QgsVec
     // (important especially e.g. for postgis primary key generated from a sequence)
     for ( int k = 0; k < newAttrs.count(); ++k )
     {
-      if ( newAttrs.at( k ).isNull() && !defaultValues.at( k ).isNull() )
-        newAttrs[k] = defaultValues.at( k );
+      if ( !newAttrs.at( k ).isNull() )
+        continue;
+
+      if ( !remoteLayer->defaultValueExpression( k ).isEmpty() )
+        newAttrs[k] = remoteLayer->defaultValue( k, f, &context );
+      else if ( remoteFlds.fieldOrigin( k ) == QgsFields::OriginProvider )
+        newAttrs[k] = remoteLayer->dataProvider()->defaultValue( remoteFlds.fieldOriginIndex( k ) );
     }
 
     f.setAttributes( newAttrs );