Fixes relation reference widget when chain filter option is activated, fixes #16903 (backport)

src/gui/editorwidgets/qgsrelationreferencewidget.cpp

@@ -191,10 +191,10 @@ void QgsRelationReferenceWidget::setRelation( const QgsRelation& relation, bool
     mReferencedFieldIdx = mReferencedLayer->fieldNameIndex( relation.fieldPairs().at( 0 ).second );
     mReferencingFieldIdx = mReferencingLayer->fieldNameIndex( relation.fieldPairs().at( 0 ).first );
 
-    QgsAttributeEditorContext context( mEditorContext, relation, QgsAttributeEditorContext::Single, QgsAttributeEditorContext::Embed );
 
     if ( mEmbedForm )
     {
+      QgsAttributeEditorContext context( mEditorContext, relation, QgsAttributeEditorContext::Single, QgsAttributeEditorContext::Embed );
       mAttributeEditorFrame->setTitle( mReferencedLayer->name() );
       mReferencedAttributeForm = new QgsAttributeForm( relation.referencedLayer(), QgsFeature(), context, this );
       mAttributeEditorLayout->addWidget( mReferencedAttributeForm );
@@ -464,6 +464,10 @@ void QgsRelationReferenceWidget::init()
       {
         QVariantList uniqueValues;
         int idx = mReferencedLayer->fieldNameIndex( fieldName );
+
+        if ( idx == -1 )
+          continue;
+
         QComboBox* cb = new QComboBox();
         cb->setProperty( "Field", fieldName );
         cb->setProperty( "FieldAlias", mReferencedLayer->attributeDisplayName( idx ) );
@@ -785,13 +789,41 @@ void QgsRelationReferenceWidget::filterChanged()
 {
   QVariant nullValue = QSettings().value( "qgis/nullValue", "NULL" );
 
-  QStringList filters;
+  QMap<QString, QString> filters;
   QgsAttributeList attrs;
 
   QComboBox* scb = qobject_cast<QComboBox*>( sender() );
 
   Q_ASSERT( scb );
 
+  QgsFeature f;
+  QgsFeatureIds featureIds;
+  QString filterExpression;
+
+  // comboboxes have to be disabled before building filters
+  if ( mChainFilters )
+    disableChainedComboBoxes( scb );
+
+  // build filters
+  Q_FOREACH ( QComboBox *cb, mFilterComboBoxes )
+  {
+    if ( cb->currentIndex() != 0 )
+    {
+      const QString fieldName = cb->property( "Field" ).toString();
+
+      if ( cb->currentText() == nullValue.toString() )
+      {
+        filters[fieldName] = QString( "\"%1\" IS NULL" ).arg( fieldName );
+      }
+      else
+      {
+        filters[fieldName] = QgsExpression::createFieldEqualityExpression( fieldName, cb->currentText() );
+      }
+      attrs << mReferencedLayer->fieldNameIndex( fieldName );
+    }
+  }
+
+  bool filtered = false;
   if ( mChainFilters )
   {
     QComboBox* ccb = nullptr;
@@ -805,13 +837,11 @@ void QgsRelationReferenceWidget::filterChanged()
         continue;
       }
 
-      if ( ccb->currentIndex() == 0 )
-      {
-        cb->setCurrentIndex( 0 );
-        cb->setEnabled( false );
-      }
-      else
+      if ( ccb->currentIndex() != 0 )
       {
+        const QString fieldName = cb->property( "Field" ).toString();
+        filtered = true;
+
         cb->blockSignals( true );
         cb->clear();
         cb->addItem( cb->property( "FieldAlias" ).toString() );
@@ -821,8 +851,30 @@ void QgsRelationReferenceWidget::filterChanged()
         QStringList texts;
         Q_FOREACH ( const QString& txt, mFilterCache[ccb->property( "Field" ).toString()][ccb->currentText()] )
         {
-          texts << txt;
+          QMap<QString, QString> filtersAttrs = filters;
+          filtersAttrs[fieldName] = QgsExpression::createFieldEqualityExpression( fieldName, txt );
+          QStringList vals = filtersAttrs.values();
+          QString expression = vals.join( QString( " AND " ) );
+
+          QgsAttributeList subset = attrs;
+          subset << mReferencedLayer->fieldNameIndex( fieldName );
+
+          QgsFeatureIterator it( mMasterModel->layerCache()->getFeatures( QgsFeatureRequest().setFilterExpression( expression ).setSubsetOfAttributes( subset ) ) );
+
+          bool found = false;
+          while ( it.nextFeature( f ) )
+          {
+            if ( !featureIds.contains( f.id() ) )
+              featureIds << f.id();
+
+            found = true;
+          }
+
+          // item is only provided if at least 1 feature exists
+          if ( found )
+            texts << txt;
         }
+
         texts.sort();
         cb->addItems( texts );
 
@@ -834,34 +886,21 @@ void QgsRelationReferenceWidget::filterChanged()
     }
   }
 
-  Q_FOREACH ( QComboBox* cb, mFilterComboBoxes )
+  if ( !mChainFilters || ( mChainFilters && !filtered ) )
   {
-    if ( cb->currentIndex() != 0 )
-    {
-      const QString fieldName = cb->property( "Field" ).toString();
+    QStringList vals = filters.values();
+    filterExpression = vals.join( QString( " AND " ) );
 
-      if ( cb->currentText() == nullValue.toString() )
-      {
-        filters << QString( "\"%1\" IS NULL" ).arg( fieldName );
-      }
-      else
-      {
-        filters << QgsExpression::createFieldEqualityExpression( fieldName, cb->currentText() );
-      }
-      attrs << mReferencedLayer->fieldNameIndex( fieldName );
-    }
-  }
-
-  QString filterExpression = filters.join( " AND " );
+    QgsFeatureRequest req = QgsFeatureRequest().setSubsetOfAttributes( attrs );
+    if ( !filterExpression.isEmpty() )
+      req.setFilterExpression( filterExpression );
 
-  QgsFeatureIterator it( mMasterModel->layerCache()->getFeatures( QgsFeatureRequest().setFilterExpression( filterExpression ).setSubsetOfAttributes( attrs ) ) );
+    QgsFeatureIterator it( mMasterModel->layerCache()->getFeatures( req ) );
 
-  QgsFeature f;
-  QgsFeatureIds featureIds;
-
-  while ( it.nextFeature( f ) )
-  {
-    featureIds << f.id();
+    while ( it.nextFeature( f ) )
+    {
+      featureIds << f.id();
+    }
   }
 
   mFilterModel->setFilteredFeatures( featureIds );
@@ -896,3 +935,28 @@ void QgsRelationReferenceWidget::updateAddEntryButton()
   mAddEntryButton->setVisible( mAllowAddFeatures );
   mAddEntryButton->setEnabled( mReferencedLayer && mReferencedLayer->isEditable() );
 }
+
+void QgsRelationReferenceWidget::disableChainedComboBoxes( const QComboBox *scb )
+{
+  QComboBox *ccb = nullptr;
+  Q_FOREACH ( QComboBox *cb, mFilterComboBoxes )
+  {
+    if ( !ccb )
+    {
+      if ( cb == scb )
+      {
+        ccb = cb;
+      }
+
+      continue;
+    }
+
+    if ( ccb->currentIndex() == 0 )
+    {
+      cb->setCurrentIndex( 0 );
+      cb->setEnabled( false );
+    }
+    else
+      ccb = cb;
+  }
+}

src/gui/editorwidgets/qgsrelationreferencewidget.h

@@ -162,6 +162,7 @@ class GUI_EXPORT QgsRelationReferenceWidget : public QWidget
   private:
     void highlightFeature( QgsFeature f = QgsFeature(), CanvasExtent canvasExtent = Fixed );
     void updateAttributeEditorFrame( const QgsFeature& feature );
+    void disableChainedComboBoxes( const QComboBox *scb );
 
     // initialized
     QgsAttributeEditorContext mEditorContext;
@@ -218,6 +219,8 @@ class GUI_EXPORT QgsRelationReferenceWidget : public QWidget
     QVBoxLayout* mAttributeEditorLayout;
     QLineEdit* mLineEdit;
     QLabel* mInvalidLabel;
+
+    friend class TestQgsRelationReferenceWidget;
 };
 
 #endif // QGSRELATIONREFERENCEWIDGET_H

tests/src/gui/CMakeLists.txt

@@ -14,6 +14,7 @@ INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR}
   ${CMAKE_CURRENT_SOURCE_DIR}/../../../src/gui/editorwidgets/core
   ${CMAKE_CURRENT_SOURCE_DIR}/../../../src/gui/symbology-ng
   ${CMAKE_CURRENT_SOURCE_DIR}/../../../src/gui/raster
+  ${CMAKE_CURRENT_SOURCE_DIR}/../../../src/gui/attributetable
   ${CMAKE_CURRENT_SOURCE_DIR}/../../../src/core
   ${CMAKE_CURRENT_SOURCE_DIR}/../../../src/core/auth
   ${CMAKE_CURRENT_SOURCE_DIR}/../../../src/core/composer
@@ -145,3 +146,4 @@ ADD_QGIS_TEST(sqlcomposerdialog testqgssqlcomposerdialog.cpp)
 ADD_QGIS_TEST(filedownloader testqgsfiledownloader.cpp)
 ADD_QGIS_TEST(composergui testqgscomposergui.cpp)
 ADD_QGIS_TEST(valuerelationwidgetwrapper testqgsvaluerelationwidgetwrapper.cpp)
+ADD_QGIS_TEST(relationreferencewidget testqgsrelationreferencewidget.cpp)