Fix feature's value action not working (fix #14536)

Replace broken/missing $currfield with new @current_field
expression variable. Update other default actions to use
expression variables instead of deprecated special columns.

python/core/qgsattributeaction.sip

@@ -62,15 +62,30 @@ class QgsAttributeAction
                    const QgsFeature &feat,
                    int defaultValueIndex = 0 ) /PyName=doActionFeature/;
 
+    /** Does the action using the expression engine to replace any embedded expressions
+     * in the action definition.
+     * @param index action index
+     * @param feature feature to run action for
+     * @param context expression context to evalute expressions under
+     * @param substitutionMap deprecated - kept for compatibilty with projects, will be removed for 3.0
+     */
+    // TODO QGIS 3.0 remove substition map - force use of expression variables
+    void doAction( int index,
+                   const QgsFeature& feature,
+                   const QgsExpressionContext& context,
+                   const QMap<QString, QVariant> *substitutionMap = nullptr );
+
+
     /** Does the action using the expression builder to expand it
      *  and getting values from the passed feature attribute map.
      *  substitutionMap is used to pass custom substitutions, to replace
      *  each key in the map with the associated value
      *  @note available in python bindings as doActionFeatureWithSubstitution
+     *  @deprecated use QgsExpressionContext variant instead
      */
     void doAction( int index,
                    const QgsFeature &feat,
-                   const QMap<QString, QVariant> *substitutionMap ) /PyName=doActionFeatureWithSubstitution/;
+                   const QMap<QString, QVariant> *substitutionMap ) /Deprecated,PyName=doActionFeatureWithSubstitution/;
 
     //! Removes all actions
     void clearActions();

src/app/qgsattributeactiondialog.cpp

@@ -298,8 +298,8 @@ void QgsAttributeActionDialog::addDefaultActions()
   insertRow( pos++, QgsAction::Generic, tr( "Echo attribute's value" ), "echo \"[% \"MY_FIELD\" %]\"", "", true );
   insertRow( pos++, QgsAction::Generic, tr( "Run an application" ), "ogr2ogr -f \"ESRI Shapefile\" \"[% \"OUTPUT_PATH\" %]\" \"[% \"INPUT_FILE\" %]\"", "", true );
   insertRow( pos++, QgsAction::GenericPython, tr( "Get feature id" ), "QtGui.QMessageBox.information(None, \"Feature id\", \"feature id is [% $id %]\")", "", false );
-  insertRow( pos++, QgsAction::GenericPython, tr( "Selected field's value (Identify features tool)" ), "QtGui.QMessageBox.information(None, \"Current field's value\", \"[% $currentfield %]\")", "", false );
-  insertRow( pos++, QgsAction::GenericPython, tr( "Clicked coordinates (Run feature actions tool)" ), "QtGui.QMessageBox.information(None, \"Clicked coords\", \"layer: [% $layerid %]\\ncoords: ([% $clickx %],[% $clicky %])\")", "", false );
+  insertRow( pos++, QgsAction::GenericPython, tr( "Selected field's value (Identify features tool)" ), "QtGui.QMessageBox.information(None, \"Current field's value\", \"[% @current_field %]\")", "", false );
+  insertRow( pos++, QgsAction::GenericPython, tr( "Clicked coordinates (Run feature actions tool)" ), "QtGui.QMessageBox.information(None, \"Clicked coords\", \"layer: [% @layer_id %]\\ncoords: ([% @click_x %],[% @click_y %])\")", "", false );
   insertRow( pos++, QgsAction::OpenUrl, tr( "Open file" ), "[% \"PATH\" %]", "", false );
   insertRow( pos++, QgsAction::OpenUrl, tr( "Search on web based on attribute's value" ), "http://www.google.com/search?q=[% \"ATTRIBUTE\" %]", "", false );
 }

src/app/qgsmaptoolfeatureaction.cpp

@@ -136,14 +136,25 @@ bool QgsMapToolFeatureAction::doAction( QgsVectorLayer *layer, int x, int y )
     if ( layer->actions()->defaultAction() >= 0 )
     {
       // define custom substitutions: layer id and clicked coords
+
+      // TODO QGIS 3.0 - remove these deprecated global expression variables!
       QMap<QString, QVariant> substitutionMap;
       substitutionMap.insert( "$layerid", layer->id() );
       point = toLayerCoordinates( layer, point );
       substitutionMap.insert( "$clickx", point.x() );
       substitutionMap.insert( "$clicky", point.y() );
 
+      QgsExpressionContext context;
+      context << QgsExpressionContextUtils::globalScope()
+      << QgsExpressionContextUtils::projectScope()
+      << QgsExpressionContextUtils::mapSettingsScope( mCanvas->mapSettings() );
+      QgsExpressionContextScope* actionScope = new QgsExpressionContextScope();
+      actionScope->setVariable( "click_x", point.x() );
+      actionScope->setVariable( "click_y", point.y() );
+      context << actionScope;
+
       int actionIdx = layer->actions()->defaultAction();
-      layer->actions()->doAction( actionIdx, feat, &substitutionMap );
+      layer->actions()->doAction( actionIdx, feat, context, &substitutionMap );
     }
     else
     {

src/core/qgsactionmanager.cpp

@@ -65,15 +65,34 @@ void QgsActionManager::removeAction( int index )
 
 void QgsActionManager::doAction( int index, const QgsFeature& feat, int defaultValueIndex )
 {
-  QMap<QString, QVariant> substitutionMap;
-  if ( defaultValueIndex >= 0 )
-  {
-    QVariant defaultValue = feat.attribute( defaultValueIndex );
-    if ( defaultValue.isValid() )
-      substitutionMap.insert( "$currfield", defaultValue );
-  }
+  QgsExpressionContext context = createExpressionContext();
+  QgsExpressionContextScope* actionScope = new QgsExpressionContextScope();
+  actionScope->setVariable( "current_field", feat.attribute( defaultValueIndex ) );
+  context << actionScope;
+  doAction( index, feat, context );
+}
+
+void QgsActionManager::doAction( int index, const QgsFeature& feat, const QgsExpressionContext& context, const QMap<QString, QVariant> *substitutionMap )
+{
+  if ( index < 0 || index >= size() )
+    return;
+
+  const QgsAction &action = at( index );
+  if ( !action.runable() )
+    return;
+
+  QgsExpressionContext actionContext( context );
+
+  if ( mLayer )
+    actionContext << QgsExpressionContextUtils::layerScope( mLayer );
+  actionContext.setFeature( feat );
 
-  doAction( index, feat, &substitutionMap );
+  QString expandedAction = QgsExpression::replaceExpressionText( action.action(), &actionContext, substitutionMap );
+  if ( expandedAction.isEmpty() )
+    return;
+
+  QgsAction newAction( action.type(), action.name(), expandedAction, action.capture() );
+  runAction( newAction );
 }
 
 void QgsActionManager::doAction( int index, const QgsFeature &feat, const QMap<QString, QVariant> *substitutionMap )

src/core/qgsactionmanager.h

@@ -85,15 +85,29 @@ class CORE_EXPORT QgsActionManager
                    const QgsFeature &feat,
                    int defaultValueIndex = 0 );
 
+    /** Does the action using the expression engine to replace any embedded expressions
+     * in the action definition.
+     * @param index action index
+     * @param feature feature to run action for
+     * @param context expression context to evalute expressions under
+     * @param substitutionMap deprecated - kept for compatibilty with projects, will be removed for 3.0
+     */
+    // TODO QGIS 3.0 remove substition map - force use of expression variables
+    void doAction( int index,
+                   const QgsFeature& feature,
+                   const QgsExpressionContext& context,
+                   const QMap<QString, QVariant> *substitutionMap = nullptr );
+
     /** Does the action using the expression builder to expand it
      *  and getting values from the passed feature attribute map.
      *  substitutionMap is used to pass custom substitutions, to replace
      *  each key in the map with the associated value
      *  @note available in python bindings as doActionFeatureWithSubstitution
+     *  @deprecated use QgsExpressionContext variant instead
      */
-    void doAction( int index,
-                   const QgsFeature &feat,
-                   const QMap<QString, QVariant> *substitutionMap );
+    Q_DECL_DEPRECATED void doAction( int index,
+                                     const QgsFeature &feat,
+                                     const QMap<QString, QVariant> *substitutionMap );
 
     //! Removes all actions
     void clearActions();