Check if join information is for auxiliary layer when filtering

python/core/qgsvectorlayerjoinbuffer.sip

@@ -130,6 +130,18 @@ Quick way to test if there is any join at all
  :rtype: QgsFeature
 %End
 
+    bool isAuxiliaryJoin( const QgsVectorLayerJoinInfo &info ) const;
+%Docstring
+ Returns true if the join information is about auxiliary layer, false otherwise
+
+ \param info The join information
+
+ :return: true if the join information is about auxiliary layer, false otherwise
+
+.. versionadded:: 3.0
+ :rtype: bool
+%End
+
     QgsVectorLayerJoinBuffer *clone() const /Factory/;
 %Docstring
  Create a copy of the join buffer

src/app/qgisapp.cpp

@@ -79,6 +79,7 @@
 #include "qgstaskmanager.h"
 #include "qgsziputils.h"
 #include "qgsbrowsermodel.h"
+#include "qgsvectorlayerjoinbuffer.h"
 
 #ifdef HAVE_3D
 #include "qgsabstract3drenderer.h"
@@ -8635,7 +8636,14 @@ void QgisApp::layerSubsetString()
   if ( !vlayer )
     return;
 
-  if ( !vlayer->vectorJoins().isEmpty() )
+  bool joins = !vlayer->vectorJoins().isEmpty();
+  if ( vlayer->vectorJoins().size() == 1 )
+  {
+    QgsVectorLayerJoinInfo info = vlayer->vectorJoins()[0];
+    joins = !vlayer->joinBuffer()->isAuxiliaryJoin( info );
+  }
+
+  if ( joins )
   {
     if ( QMessageBox::question( nullptr, tr( "Filter on joined fields" ),
                                 tr( "You are about to set a subset filter on a layer that has joined fields. "

src/core/qgsvectorlayerjoinbuffer.cpp

@@ -21,6 +21,7 @@
 #include "qgslogger.h"
 #include "qgsproject.h"
 #include "qgsvectordataprovider.h"
+#include "qgsauxiliarystorage.h"
 
 #include <QDomElement>
 
@@ -265,6 +266,9 @@ void QgsVectorLayerJoinBuffer::writeXml( QDomNode &layer_node, QDomDocument &doc
   QList< QgsVectorLayerJoinInfo >::const_iterator joinIt = mVectorJoins.constBegin();
   for ( ; joinIt != mVectorJoins.constEnd(); ++joinIt )
   {
+    if ( isAuxiliaryJoin( *joinIt ) )
+      continue;
+
     QDomElement joinElem = document.createElement( QStringLiteral( "join" ) );
 
     joinElem.setAttribute( QStringLiteral( "targetFieldName" ), joinIt->targetFieldName() );
@@ -656,3 +660,13 @@ bool QgsVectorLayerJoinBuffer::deleteFeatures( const QgsFeatureIds &fids ) const
 
   return true;
 }
+
+bool QgsVectorLayerJoinBuffer::isAuxiliaryJoin( const QgsVectorLayerJoinInfo &info ) const
+{
+  const QgsAuxiliaryLayer *al = mLayer->auxiliaryLayer();
+
+  if ( al && al->id() == info.joinLayerId() )
+    return true;
+  else
+    return false;
+}

src/core/qgsvectorlayerjoinbuffer.h

@@ -121,6 +121,17 @@ class CORE_EXPORT QgsVectorLayerJoinBuffer : public QObject, public QgsFeatureSi
      */
     QgsFeature targetedFeatureOf( const QgsVectorLayerJoinInfo *info, const QgsFeature &feature ) const;
 
+    /**
+     * Returns true if the join information is about auxiliary layer, false otherwise
+     *
+     * \param info The join information
+     *
+     * \returns true if the join information is about auxiliary layer, false otherwise
+     *
+     * \since QGIS 3.0
+     */
+    bool isAuxiliaryJoin( const QgsVectorLayerJoinInfo &info ) const;
+
     /**
      * Create a copy of the join buffer
      * \since QGIS 2.6