Fix #10912 (joined attributes are not correctly propagated in nested …

…joins)

This commit makes QgsVectorLayerJoinBuffer listen to changes in fields
of joined vector layers in order to update the cache and inform parent layer

python/core/qgsfield.sip

@@ -193,6 +193,11 @@ class QgsFields
     //! Utility function to return a list of QgsField instances
     QList<QgsField> toList() const;
 
+    //! @note added in 2.6
+    bool operator==( const QgsFields& other ) const;
+    //! @note added in 2.6
+    bool operator!=( const QgsFields& other ) const;
+
 /*  SIP_PYOBJECT __getitem__(int key);
 %MethodCode
   if (a0 = sipConvertFromSequenceIndex(a0, sipCpp->count()) < 0)

python/core/qgsvectorlayerjoinbuffer.sip

@@ -1,4 +1,4 @@
-class QgsVectorLayerJoinBuffer
+class QgsVectorLayerJoinBuffer : QObject
 {
 %TypeHeaderCode
 #include <qgsvectorlayerjoinbuffer.h>
@@ -39,4 +39,12 @@ class QgsVectorLayerJoinBuffer
       @param sourceFieldIndex Output: field's index in source layer */
     const QgsVectorJoinInfo* joinForFieldIndex( int index, const QgsFields& fields, int& sourceFieldIndex /Out/ ) const;
 
+    //! Create a copy of the join buffer
+    //! @note added in 2.6
+    QgsVectorLayerJoinBuffer* clone() const /Factory/;
+
+  signals:
+    //! Emitted whenever the list of joined fields changes (e.g. added join or joined layer's fields change)
+    //! @note added in 2.6
+    void joinedFieldsChanged();
 };

src/core/CMakeLists.txt

@@ -369,6 +369,7 @@ SET(QGIS_CORE_MOC_HDRS
   qgsnetworkaccessmanager.h
   qgsvectordataprovider.h
   qgsvectorlayercache.h
+  qgsvectorlayerjoinbuffer.h
   qgsgeometryvalidator.h
 
   composer/qgsaddremoveitemcommand.h

src/core/qgsfield.h

@@ -178,6 +178,11 @@ class CORE_EXPORT QgsFields
       Field(): origin( OriginUnknown ), originIndex( -1 ) {}
       Field( const QgsField& f, FieldOrigin o, int oi ): field( f ), origin( o ), originIndex( oi ) {}
 
+      //! @note added in 2.6
+      bool operator==( const Field& other ) const { return field == other.field && origin == other.origin && originIndex == other.originIndex; }
+      //! @note added in 2.6
+      bool operator!=( const Field& other ) const { return !( *this == other ); }
+
       QgsField field;      //!< field
       FieldOrigin origin;  //!< origin of the field
       int originIndex;     //!< index specific to the origin
@@ -238,6 +243,11 @@ class CORE_EXPORT QgsFields
     //! Utility function to return a list of QgsField instances
     QList<QgsField> toList() const;
 
+    //! @note added in 2.6
+    bool operator==( const QgsFields& other ) const { return mFields == other.mFields; }
+    //! @note added in 2.6
+    bool operator!=( const QgsFields& other ) const { return ! ( *this == other ); }
+
   protected:
     //! internal storage of the container
     QVector<Field> mFields;

src/core/qgsvectorlayer.cpp

@@ -1304,6 +1304,7 @@ bool QgsVectorLayer::readXml( const QDomNode& layer_node )
   if ( !mJoinBuffer )
   {
     mJoinBuffer = new QgsVectorLayerJoinBuffer();
+    connect( mJoinBuffer, SIGNAL( joinedFieldsChanged() ), this, SLOT( onJoinedFieldsChanged() ) );
   }
   mJoinBuffer->readXml( layer_node );
 
@@ -1366,6 +1367,7 @@ bool QgsVectorLayer::setDataProvider( QString const & provider )
       mWkbType = mDataProvider->geometryType();
 
       mJoinBuffer = new QgsVectorLayerJoinBuffer();
+      connect( mJoinBuffer, SIGNAL( joinedFieldsChanged() ), this, SLOT( onJoinedFieldsChanged() ) );
       mExpressionFieldBuffer = new QgsExpressionFieldBuffer();
       updateFields();
 
@@ -2782,6 +2784,8 @@ void QgsVectorLayer::updateFields()
   if ( !mDataProvider )
     return;
 
+  QgsFields oldFields = mUpdatedFields;
+
   mUpdatedFields = mDataProvider->fields();
 
   // added / removed fields
@@ -2795,7 +2799,8 @@ void QgsVectorLayer::updateFields()
   if ( mExpressionFieldBuffer )
     mExpressionFieldBuffer->updateFields( mUpdatedFields );
 
-  emit updatedFields();
+  if ( oldFields != mUpdatedFields )
+    emit updatedFields();
 }
 
 
@@ -3563,6 +3568,12 @@ void QgsVectorLayer::onRelationsLoaded()
   }
 }
 
+void QgsVectorLayer::onJoinedFieldsChanged()
+{
+  // some of the fields of joined layers have changed -> we need to update this layer's fields too
+  updateFields();
+}
+
 QgsVectorLayer::ValueRelationData QgsVectorLayer::valueRelation( int idx )
 {
   if ( editorWidgetV2( idx ) == "ValueRelation" )

src/core/qgsvectorlayer.h

@@ -1641,6 +1641,7 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
 
   private slots:
     void onRelationsLoaded();
+    void onJoinedFieldsChanged();
 
   protected:
     /** Set the extent */

src/core/qgsvectorlayerfeatureiterator.cpp

@@ -27,7 +27,7 @@ QgsVectorLayerFeatureSource::QgsVectorLayerFeatureSource( QgsVectorLayer *layer
 {
   mProviderFeatureSource = layer->dataProvider()->featureSource();
   mFields = layer->pendingFields();
-  mJoinBuffer = new QgsVectorLayerJoinBuffer( *layer->mJoinBuffer );
+  mJoinBuffer = layer->mJoinBuffer->clone();
   mExpressionFieldBuffer = new QgsExpressionFieldBuffer( *layer->mExpressionFieldBuffer );
 
   mCanBeSimplified = layer->hasGeometryType() && layer->geometryType() != QGis::Point;

src/core/qgsvectorlayerjoinbuffer.cpp

@@ -39,8 +39,18 @@ void QgsVectorLayerJoinBuffer::addJoin( const QgsVectorJoinInfo& joinInfo )
   {
     cacheJoinLayer( mVectorJoins.last() );
   }
+
+  // Wait for notifications about changed fields in joined layer to propagate them.
+  // During project load the joined layers possibly do not exist yet so the connection will not be created,
+  // but then QgsProject makes sure to call createJoinCaches() which will do the connection.
+  // Unique connection makes sure we do not respond to one layer's update more times (in case of multiple join)
+  if ( QgsVectorLayer* vl = qobject_cast<QgsVectorLayer*>( QgsMapLayerRegistry::instance()->mapLayer( joinInfo.joinLayerId ) ) )
+    connect( vl, SIGNAL( updatedFields() ), this, SLOT( joinedLayerUpdatedFields() ), Qt::UniqueConnection );
+
+  emit joinedFieldsChanged();
 }
 
+
 void QgsVectorLayerJoinBuffer::removeJoin( const QString& joinLayerId )
 {
   for ( int i = 0; i < mVectorJoins.size(); ++i )
@@ -50,6 +60,11 @@ void QgsVectorLayerJoinBuffer::removeJoin( const QString& joinLayerId )
       mVectorJoins.removeAt( i );
     }
   }
+
+  if ( QgsVectorLayer* vl = qobject_cast<QgsVectorLayer*>( QgsMapLayerRegistry::instance()->mapLayer( joinLayerId ) ) )
+    disconnect( vl, SIGNAL( updatedFields() ), this, SLOT( joinedLayerUpdatedFields() ) );
+
+  emit joinedFieldsChanged();
 }
 
 void QgsVectorLayerJoinBuffer::cacheJoinLayer( QgsVectorJoinInfo& joinInfo )
@@ -121,6 +136,10 @@ void QgsVectorLayerJoinBuffer::createJoinCaches()
   for ( ; joinIt != mVectorJoins.end(); ++joinIt )
   {
     cacheJoinLayer( *joinIt );
+
+    // make sure we are connected to the joined layer
+    if ( QgsVectorLayer* vl = qobject_cast<QgsVectorLayer*>( QgsMapLayerRegistry::instance()->mapLayer( joinIt->joinLayerId ) ) )
+      connect( vl, SIGNAL( updatedFields() ), this, SLOT( joinedLayerUpdatedFields() ), Qt::UniqueConnection );
   }
 }
 
@@ -188,3 +207,28 @@ const QgsVectorJoinInfo* QgsVectorLayerJoinBuffer::joinForFieldIndex( int index,
 
   return &( mVectorJoins[sourceJoinIndex] );
 }
+
+QgsVectorLayerJoinBuffer* QgsVectorLayerJoinBuffer::clone() const
+{
+  QgsVectorLayerJoinBuffer* cloned = new QgsVectorLayerJoinBuffer;
+  cloned->mVectorJoins = mVectorJoins;
+  return cloned;
+}
+
+void QgsVectorLayerJoinBuffer::joinedLayerUpdatedFields()
+{
+  QgsVectorLayer* joinedLayer = qobject_cast<QgsVectorLayer*>( sender() );
+  Q_ASSERT( joinedLayer );
+
+  // recache the joined layer
+  for ( QgsVectorJoinList::iterator it = mVectorJoins.begin(); it != mVectorJoins.end(); ++it )
+  {
+    if ( joinedLayer->id() == it->joinLayerId )
+    {
+      it->cachedAttributes.clear();
+      cacheJoinLayer( *it );
+    }
+  }
+
+  emit joinedFieldsChanged();
+}

src/core/qgsvectorlayerjoinbuffer.h

@@ -25,11 +25,13 @@
 #include <QString>
 
 
+typedef QList< QgsVectorJoinInfo > QgsVectorJoinList;
 
 
 /**Manages joined fields for a vector layer*/
-class CORE_EXPORT QgsVectorLayerJoinBuffer
+class CORE_EXPORT QgsVectorLayerJoinBuffer : public QObject
 {
+    Q_OBJECT
   public:
     QgsVectorLayerJoinBuffer();
     ~QgsVectorLayerJoinBuffer();
@@ -58,18 +60,30 @@ class CORE_EXPORT QgsVectorLayerJoinBuffer
     /**Quick way to test if there is any join at all*/
     bool containsJoins() const { return !mVectorJoins.isEmpty(); }
 
-    const QList< QgsVectorJoinInfo >& vectorJoins() const { return mVectorJoins; }
+    const QgsVectorJoinList& vectorJoins() const { return mVectorJoins; }
 
     /**Finds the vector join for a layer field index.
       @param index this layers attribute index
       @param fields fields of the vector layer (including joined fields)
       @param sourceFieldIndex Output: field's index in source layer */
     const QgsVectorJoinInfo* joinForFieldIndex( int index, const QgsFields& fields, int& sourceFieldIndex ) const;
 
+    //! Create a copy of the join buffer
+    //! @note added in 2.6
+    QgsVectorLayerJoinBuffer* clone() const;
+
+  signals:
+    //! Emitted whenever the list of joined fields changes (e.g. added join or joined layer's fields change)
+    //! @note added in 2.6
+    void joinedFieldsChanged();
+
+  private slots:
+    void joinedLayerUpdatedFields();
+
   private:
 
     /**Joined vector layers*/
-    QList< QgsVectorJoinInfo > mVectorJoins;
+    QgsVectorJoinList mVectorJoins;
 
     /**Caches attributes of join layer in memory if QgsVectorJoinInfo.memoryCache is true (and the cache is not already there)*/
     void cacheJoinLayer( QgsVectorJoinInfo& joinInfo );

tests/src/core/CMakeLists.txt

@@ -133,3 +133,4 @@ ADD_QGIS_TEST(colorschemeregistry testqgscolorschemeregistry.cpp)
 ADD_QGIS_TEST(colorscheme testqgscolorscheme.cpp)
 ADD_QGIS_TEST(networkcontentfetcher testqgsnetworkcontentfetcher.cpp )
 ADD_QGIS_TEST(legendrenderertest testqgslegendrenderer.cpp )
+ADD_QGIS_TEST(vectorlayerjoinbuffer testqgsvectorlayerjoinbuffer.cpp )