qgsabstractrelationeditorwidget.cpp

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/***************************************************************************
                         qgsabstractrelationeditorwidget.cpp
                         ----------------------
    begin                : October 2020
    copyright            : (C) 2020 by Ivan Ivanov
    email                : [email protected]
 ***************************************************************************/
 
/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
 
#include "qgsabstractrelationeditorwidget.h"
#include "moc_qgsabstractrelationeditorwidget.cpp"
 
#include "qgsfeatureiterator.h"
#include "qgsexpression.h"
#include "qgsexpressioncontextutils.h"
#include "qgsfeature.h"
#include "qgsfeatureselectiondlg.h"
#include "qgsrelation.h"
#include "qgsrelationmanager.h"
#include "qgspolymorphicrelation.h"
#include "qgsvectorlayertools.h"
#include "qgsproject.h"
#include "qgstransactiongroup.h"
#include "qgsvectorlayerutils.h"
 
#include <QMessageBox>
#include <QPushButton>
 
QgsAbstractRelationEditorWidget::QgsAbstractRelationEditorWidget( const QVariantMap &config, QWidget *parent )
  : QWidget( parent )
{
  Q_UNUSED( config );
}
 
void QgsAbstractRelationEditorWidget::setRelationFeature( const QgsRelation &relation, const QgsFeature &feature )
{
  beforeSetRelationFeature( relation, feature );
 
  mRelation = relation;
  mFeatureList.clear();
  mFeatureList.append( feature );
 
  setObjectName( QStringLiteral( "referenced/" ) + mRelation.name() );
 
  afterSetRelationFeature();
  updateUi();
}
 
void QgsAbstractRelationEditorWidget::setRelations( const QgsRelation &relation, const QgsRelation &nmrelation )
{
  beforeSetRelations( relation, nmrelation );
 
  mRelation = relation;
  mNmRelation = nmrelation;
 
  if ( !mRelation.isValid() )
  {
    afterSetRelations();
    return;
  }
 
  mLayerInSameTransactionGroup = false;
 
  const auto transactionGroups = QgsProject::instance()->transactionGroups();
  for ( auto it = transactionGroups.constBegin(); it != transactionGroups.constEnd(); ++it )
  {
    if ( mNmRelation.isValid() )
    {
      if ( it.value()->layers().contains( mRelation.referencedLayer() ) && it.value()->layers().contains( mRelation.referencingLayer() ) && it.value()->layers().contains( mNmRelation.referencedLayer() ) )
        mLayerInSameTransactionGroup = true;
    }
    else
    {
      if ( it.value()->layers().contains( mRelation.referencedLayer() ) && it.value()->layers().contains( mRelation.referencingLayer() ) )
        mLayerInSameTransactionGroup = true;
    }
  }
 
  setObjectName( QStringLiteral( "referenced/" ) + mRelation.name() );
 
  afterSetRelations();
  updateUi();
}
 
void QgsAbstractRelationEditorWidget::setEditorContext( const QgsAttributeEditorContext &context )
{
  mEditorContext = context;
}
 
QgsAttributeEditorContext QgsAbstractRelationEditorWidget::editorContext() const
{
  return mEditorContext;
}
 
void QgsAbstractRelationEditorWidget::setFeature( const QgsFeature &feature, bool update )
{
  mFeatureList.clear();
  mFeatureList.append( feature );
 
  mEditorContext.setFormFeature( feature );
 
  if ( update )
    updateUi();
}
 
void QgsAbstractRelationEditorWidget::setMultiEditFeatureIds( const QgsFeatureIds &fids )
{
  mFeatureList.clear();
 
  QgsFeatureIterator featureIterator = mRelation.referencedLayer()->getFeatures( QgsFeatureRequest().setFilterFids( fids ) );
  QgsFeature feature;
  while ( featureIterator.nextFeature( feature ) )
    mFeatureList.append( feature );
 
  if ( !mFeatureList.isEmpty() )
    mEditorContext.setFormFeature( mFeatureList.first() );
}
 
void QgsAbstractRelationEditorWidget::setNmRelationId( const QVariant &nmRelationId )
{
  const QgsRelation nmrelation = QgsProject::instance()->relationManager()->relation( nmRelationId.toString() );
  beforeSetRelations( mRelation, nmrelation );
  mNmRelation = nmrelation;
  afterSetRelations();
  updateUi();
}
 
QVariant QgsAbstractRelationEditorWidget::nmRelationId() const
{
  return mNmRelation.id();
}
 
QString QgsAbstractRelationEditorWidget::label() const
{
  return QString();
}
 
void QgsAbstractRelationEditorWidget::setLabel( const QString &label )
{
  Q_UNUSED( label )
}
 
bool QgsAbstractRelationEditorWidget::showLabel() const
{
  return false;
}
 
void QgsAbstractRelationEditorWidget::setShowLabel( bool showLabel )
{
  Q_UNUSED( showLabel )
}
 
void QgsAbstractRelationEditorWidget::setForceSuppressFormPopup( bool forceSuppressFormPopup )
{
  mForceSuppressFormPopup = forceSuppressFormPopup;
}
 
bool QgsAbstractRelationEditorWidget::forceSuppressFormPopup() const
{
  return mForceSuppressFormPopup;
}
 
void QgsAbstractRelationEditorWidget::updateTitle()
{
}
 
bool QgsAbstractRelationEditorWidget::multiEditModeActive() const
{
  return mFeatureList.size() > 1;
}
 
QgsFeature QgsAbstractRelationEditorWidget::feature() const
{
  if ( !mFeatureList.isEmpty() )
    return mFeatureList.first();
 
  return QgsFeature();
}
 
QList<QgsFeature> QgsAbstractRelationEditorWidget::features() const
{
  return mFeatureList;
}
 
void QgsAbstractRelationEditorWidget::toggleEditing( bool state )
{
  if ( state )
  {
    mEditorContext.vectorLayerTools()->startEditing( mRelation.referencingLayer() );
    if ( mNmRelation.isValid() )
      mEditorContext.vectorLayerTools()->startEditing( mNmRelation.referencedLayer() );
  }
  else
  {
    mEditorContext.vectorLayerTools()->stopEditing( mRelation.referencingLayer() );
    if ( mNmRelation.isValid() )
      mEditorContext.vectorLayerTools()->stopEditing( mNmRelation.referencedLayer() );
  }
}
 
void QgsAbstractRelationEditorWidget::saveEdits()
{
  mEditorContext.vectorLayerTools()->saveEdits( mRelation.referencingLayer() );
  if ( mNmRelation.isValid() )
    mEditorContext.vectorLayerTools()->saveEdits( mNmRelation.referencedLayer() );
}
 
QgsFeatureIds QgsAbstractRelationEditorWidget::addFeature( const QgsGeometry &geometry )
{
  QgsAttributeMap keyAttrs;
 
  const QgsVectorLayerTools *vlTools = mEditorContext.vectorLayerTools();
 
  // Fields of the linking table
  const QgsFields fields = mRelation.referencingLayer()->fields();
 
  QgsFeatureIds addedFeatureIds;
 
  // For generated relations insert the referenced layer field
  switch ( mRelation.type() )
  {
    case Qgis::RelationshipType::Generated:
    {
      const QgsPolymorphicRelation polyRel = mRelation.polymorphicRelation();
      keyAttrs.insert( fields.indexFromName( polyRel.referencedLayerField() ), polyRel.layerRepresentation( mRelation.referencedLayer() ) );
      break;
    }
 
    case Qgis::RelationshipType::Normal:
      break;
  }
 
  if ( mNmRelation.isValid() )
  {
    // only normal relations support m:n relation
    Q_ASSERT( mNmRelation.type() == Qgis::RelationshipType::Normal );
 
    // n:m Relation: first let the user create a new feature on the other table
    // and autocreate a new linking feature.
    QgsFeature finalFeature;
    if ( !vlTools->addFeature( mNmRelation.referencedLayer(), QgsAttributeMap(), geometry, &finalFeature, this, false, true ) )
      return QgsFeatureIds();
 
    addedFeatureIds.insert( finalFeature.id() );
 
    // Expression context for the linking table
    QgsExpressionContext context = mRelation.referencingLayer()->createExpressionContext();
 
    QgsAttributeMap linkAttributes = keyAttrs;
    const auto constFieldPairs = mRelation.fieldPairs();
 
    QgsVectorLayerUtils::QgsFeaturesDataList linkFeatureDataList;
    for ( const QgsFeature &editingFeature : std::as_const( mFeatureList ) )
    {
      for ( const QgsRelation::FieldPair &fieldPair : constFieldPairs )
      {
        const int index = fields.indexOf( fieldPair.first );
        linkAttributes.insert( index, editingFeature.attribute( fieldPair.second ) );
      }
 
      const auto constNmFieldPairs = mNmRelation.fieldPairs();
      for ( const QgsRelation::FieldPair &fieldPair : constNmFieldPairs )
      {
        const int index = fields.indexOf( fieldPair.first );
        linkAttributes.insert( index, finalFeature.attribute( fieldPair.second ) );
      }
 
      linkFeatureDataList.append( QgsVectorLayerUtils::QgsFeatureData( QgsGeometry(), linkAttributes ) );
    }
    QgsFeatureList linkFeatureList = QgsVectorLayerUtils::createFeatures( mRelation.referencingLayer(), linkFeatureDataList, &context );
    mRelation.referencingLayer()->addFeatures( linkFeatureList );
  }
  else
  {
    const auto constFieldPairs = mRelation.fieldPairs();
    for ( const QgsRelation::FieldPair &fieldPair : constFieldPairs )
      keyAttrs.insert( fields.indexFromName( fieldPair.referencingField() ), mFeatureList.first().attribute( fieldPair.referencedField() ) );
 
    QgsVectorLayerToolsContext context;
    context.setParentWidget( this );
    context.setShowModal( false );
    context.setHideParent( true );
    std::unique_ptr<QgsExpressionContextScope> scope( QgsExpressionContextUtils::parentFormScope( mFeatureList.first(), mEditorContext.attributeFormModeString() ) );
    context.setAdditionalExpressionContextScope( scope.get() );
    QgsFeature linkFeature;
    if ( !vlTools->addFeatureV2( mRelation.referencingLayer(), keyAttrs, geometry, &linkFeature, context ) )
      return QgsFeatureIds();
 
    addedFeatureIds.insert( linkFeature.id() );
 
    // In multiedit add to other features to but without dialog
    for ( const QgsFeature &feature : std::as_const( mFeatureList ) )
    {
      // First feature already added
      if ( mFeatureList.first() == feature )
        continue;
 
      for ( const QgsRelation::FieldPair &fieldPair : constFieldPairs )
        linkFeature.setAttribute( fields.indexFromName( fieldPair.referencingField() ), feature.attribute( fieldPair.referencedField() ) );
 
      mRelation.referencingLayer()->addFeature( linkFeature );
      addedFeatureIds.insert( linkFeature.id() );
    }
  }
 
  updateUi();
 
  emit relatedFeaturesChanged();
 
  return addedFeatureIds;
}
 
void QgsAbstractRelationEditorWidget::deleteFeature( const QgsFeatureId fid )
{
  deleteFeatures( QgsFeatureIds() << fid );
 
  emit relatedFeaturesChanged();
}
 
void QgsAbstractRelationEditorWidget::deleteFeatures( const QgsFeatureIds &fids )
{
  bool deleteFeatures = true;
 
  QgsVectorLayer *layer;
  if ( mNmRelation.isValid() )
  {
    // only normal relations support m:n relation
    Q_ASSERT( mNmRelation.type() == Qgis::RelationshipType::Normal );
 
    layer = mNmRelation.referencedLayer();
 
    // When deleting a linked feature within an N:M relation,
    // check if the feature is linked to more than just one feature.
    // In case it is linked more than just once, ask the user for confirmation
    // as it is likely he was not aware of the implications and might delete
    // there may be several linking entries deleted along.
 
    QgsFeatureRequest deletedFeaturesRequest;
    deletedFeaturesRequest.setFilterFids( fids );
    deletedFeaturesRequest.setFlags( Qgis::FeatureRequestFlag::NoGeometry );
    deletedFeaturesRequest.setSubsetOfAttributes( QgsAttributeList() << mNmRelation.referencedFields().first() );
 
    QgsFeatureIterator deletedFeatures = layer->getFeatures( deletedFeaturesRequest );
    QStringList deletedFeaturesPks;
    QgsFeature feature;
    while ( deletedFeatures.nextFeature( feature ) )
    {
      deletedFeaturesPks.append( QgsExpression::quotedValue( feature.attribute( mNmRelation.referencedFields().first() ) ) );
    }
 
    QgsFeatureRequest linkingFeaturesRequest;
    linkingFeaturesRequest.setFlags( Qgis::FeatureRequestFlag::NoGeometry );
    linkingFeaturesRequest.setNoAttributes();
 
    QString linkingFeaturesRequestExpression;
    if ( !deletedFeaturesPks.empty() )
    {
      linkingFeaturesRequestExpression = QStringLiteral( "%1 IN (%2)" ).arg( QgsExpression::quotedColumnRef( mNmRelation.fieldPairs().first().first ), deletedFeaturesPks.join( ',' ) );
      linkingFeaturesRequest.setFilterExpression( linkingFeaturesRequestExpression );
 
      QgsFeatureIterator relatedLinkingFeatures = mNmRelation.referencingLayer()->getFeatures( linkingFeaturesRequest );
 
      int relatedLinkingFeaturesCount = 0;
      while ( relatedLinkingFeatures.nextFeature( feature ) )
      {
        relatedLinkingFeaturesCount++;
      }
 
      if ( deletedFeaturesPks.size() == 1 && relatedLinkingFeaturesCount > 1 )
      {
        QMessageBox messageBox( QMessageBox::Question, tr( "Really delete entry?" ), tr( "The entry on %1 is still linked to %2 features on %3. Do you want to delete it?" ).arg( mNmRelation.referencedLayer()->name(), QLocale().toString( relatedLinkingFeaturesCount ), mRelation.referencedLayer()->name() ), QMessageBox::NoButton, this );
        messageBox.addButton( QMessageBox::Cancel );
        QAbstractButton *deleteButton = messageBox.addButton( tr( "Delete" ), QMessageBox::AcceptRole );
 
        messageBox.exec();
        if ( messageBox.clickedButton() != deleteButton )
          deleteFeatures = false;
      }
      else if ( deletedFeaturesPks.size() > 1 && relatedLinkingFeaturesCount > deletedFeaturesPks.size() )
      {
        QMessageBox messageBox( QMessageBox::Question, tr( "Really delete entries?" ), tr( "The %1 entries on %2 are still linked to %3 features on %4. Do you want to delete them?" ).arg( QLocale().toString( deletedFeaturesPks.size() ), mNmRelation.referencedLayer()->name(), QLocale().toString( relatedLinkingFeaturesCount ), mRelation.referencedLayer()->name() ), QMessageBox::NoButton, this );
        messageBox.addButton( QMessageBox::Cancel );
        QAbstractButton *deleteButton = messageBox.addButton( tr( "Delete" ), QMessageBox::AcceptRole );
 
        messageBox.exec();
        if ( messageBox.clickedButton() != deleteButton )
          deleteFeatures = false;
      }
    }
  }
  else
  {
    layer = mRelation.referencingLayer();
  }
 
  QgsVectorLayerUtils::QgsDuplicateFeatureContext infoContext;
  if ( QgsVectorLayerUtils::impactsCascadeFeatures( layer, fids, QgsProject::instance(), infoContext ) )
  {
    QString childrenInfo;
    int childrenCount = 0;
    const auto infoContextLayers = infoContext.layers();
    for ( QgsVectorLayer *chl : infoContextLayers )
    {
      childrenCount += infoContext.duplicatedFeatures( chl ).size();
      childrenInfo += ( tr( "%n feature(s) on layer \"%1\", ", nullptr, infoContext.duplicatedFeatures( chl ).size() ).arg( chl->name() ) );
    }
 
    // for extra safety to make sure we know that the delete can have impact on children and joins
    const int res = QMessageBox::question( this, tr( "Delete at least %n feature(s) on other layer(s)", nullptr, childrenCount ), tr( "Delete %n feature(s) on layer \"%1\", %2 as well and all of its other descendants.\nDelete these features?", nullptr, fids.count() ).arg( layer->name() ).arg( childrenInfo ), QMessageBox::Yes | QMessageBox::No );
    if ( res != QMessageBox::Yes )
      deleteFeatures = false;
  }
 
  if ( deleteFeatures )
  {
    QgsVectorLayer::DeleteContext context( true, QgsProject::instance() );
    layer->deleteFeatures( fids, &context );
    const auto contextLayers = context.handledLayers();
    if ( contextLayers.size() > 1 )
    {
      int deletedCount = 0;
      QString feedbackMessage;
      for ( QgsVectorLayer *contextLayer : contextLayers )
      {
        feedbackMessage += tr( "%1 on layer %2. " ).arg( context.handledFeatures( contextLayer ).size() ).arg( contextLayer->name() );
        deletedCount += context.handledFeatures( contextLayer ).size();
      }
      mEditorContext.mainMessageBar()->pushMessage( tr( "%n feature(s) deleted: %2", nullptr, deletedCount ).arg( feedbackMessage ), Qgis::MessageLevel::Success );
    }
 
    updateUi();
 
    emit relatedFeaturesChanged();
  }
}
 
void QgsAbstractRelationEditorWidget::linkFeature( const QString &filterExpression )
{
  QgsVectorLayer *layer = nullptr;
 
  if ( mNmRelation.isValid() )
  {
    // only normal relations support m:n relation
    Q_ASSERT( mNmRelation.type() == Qgis::RelationshipType::Normal );
 
    layer = mNmRelation.referencedLayer();
  }
  else
  {
    if ( multiEditModeActive() )
    {
      QgsLogger::warning( tr( "For 1:n relations is not possible to link to multiple features" ) );
      return;
    }
 
    layer = mRelation.referencingLayer();
  }
 
  QgsFeatureSelectionDlg *selectionDlg = new QgsFeatureSelectionDlg( layer, mEditorContext, this );
  selectionDlg->setAttribute( Qt::WA_DeleteOnClose );
 
  const QString displayString = QgsVectorLayerUtils::getFeatureDisplayString( mRelation.referencedLayer(), mFeatureList.first() );
  selectionDlg->setWindowTitle( tr( "Link existing child features for parent %1 \"%2\"" ).arg( mRelation.referencedLayer()->name(), displayString ) );
  selectionDlg->setFilterExpression( filterExpression, QgsAttributeForm::ReplaceFilter );
 
  connect( selectionDlg, &QDialog::accepted, this, &QgsAbstractRelationEditorWidget::onLinkFeatureDlgAccepted );
  selectionDlg->show();
}
 
void QgsAbstractRelationEditorWidget::onLinkFeatureDlgAccepted()
{
  QgsFeatureSelectionDlg *selectionDlg = qobject_cast<QgsFeatureSelectionDlg *>( sender() );
 
  if ( mNmRelation.isValid() )
  {
    // only normal relations support m:n relation
    Q_ASSERT( mNmRelation.type() == Qgis::RelationshipType::Normal );
 
    // Fields of the linking table
    const QgsFields fields = mRelation.referencingLayer()->fields();
 
    QgsAttributeMap linkAttributes;
 
    switch ( mRelation.type() )
    {
      case Qgis::RelationshipType::Generated:
      {
        const QgsPolymorphicRelation polyRel = mRelation.polymorphicRelation();
        Q_ASSERT( polyRel.isValid() );
 
        linkAttributes.insert( fields.indexFromName( polyRel.referencedLayerField() ), polyRel.layerRepresentation( mRelation.referencedLayer() ) );
        break;
      }
      case Qgis::RelationshipType::Normal:
        break;
    }
 
    QgsVectorLayerUtils::QgsFeaturesDataList linkFeatureDataList;
    QgsFeature relatedFeature;
    QgsFeatureIterator it = mNmRelation.referencedLayer()->getFeatures(
      QgsFeatureRequest()
        .setFilterFids( selectionDlg->selectedFeatures() )
        .setSubsetOfAttributes( mNmRelation.referencedFields() )
    );
    while ( it.nextFeature( relatedFeature ) )
    {
      for ( const QgsFeature &editFeature : std::as_const( mFeatureList ) )
      {
        {
          const auto constFieldPairs = mRelation.fieldPairs();
          for ( const QgsRelation::FieldPair &fieldPair : constFieldPairs )
          {
            const int index = fields.indexOf( fieldPair.first );
            linkAttributes.insert( index, editFeature.attribute( fieldPair.second ) );
          }
        }
 
        const auto constFieldPairs = mNmRelation.fieldPairs();
        for ( const QgsRelation::FieldPair &fieldPair : constFieldPairs )
        {
          const int index = fields.indexOf( fieldPair.first );
          linkAttributes.insert( index, relatedFeature.attribute( fieldPair.second ) );
        }
 
        linkFeatureDataList.append( QgsVectorLayerUtils::QgsFeatureData( QgsGeometry(), linkAttributes ) );
      }
    }
 
    // Expression context for the linking table
    QgsExpressionContext context = mRelation.referencingLayer()->createExpressionContext();
 
    QgsFeatureList linkFeaturesList = QgsVectorLayerUtils::createFeatures( mRelation.referencingLayer(), linkFeatureDataList, &context );
 
    mRelation.referencingLayer()->addFeatures( linkFeaturesList );
    QgsFeatureIds ids;
    const auto constNewFeatures = linkFeaturesList;
    for ( const QgsFeature &f : constNewFeatures )
      ids << f.id();
    mRelation.referencingLayer()->selectByIds( ids );
  }
  else
  {
    if ( multiEditModeActive() )
    {
      QgsLogger::warning( tr( "For 1:n relations is not possible to link to multiple features" ) );
      return;
    }
 
    QMap<int, QVariant> keys;
    const auto constFieldPairs = mRelation.fieldPairs();
    for ( const QgsRelation::FieldPair &fieldPair : constFieldPairs )
    {
      const int idx = mRelation.referencingLayer()->fields().lookupField( fieldPair.referencingField() );
      const QVariant val = mFeatureList.first().attribute( fieldPair.referencedField() );
      keys.insert( idx, val );
    }
 
    const auto constSelectedFeatures = selectionDlg->selectedFeatures();
    for ( const QgsFeatureId fid : constSelectedFeatures )
    {
      QgsVectorLayer *referencingLayer = mRelation.referencingLayer();
      switch ( mRelation.type() )
      {
        case Qgis::RelationshipType::Generated:
        {
          const QgsPolymorphicRelation polyRel = mRelation.polymorphicRelation();
 
          Q_ASSERT( polyRel.isValid() );
 
          mRelation.referencingLayer()->changeAttributeValue( fid, referencingLayer->fields().indexFromName( polyRel.referencedLayerField() ), polyRel.layerRepresentation( mRelation.referencedLayer() ) );
          break;
        }
        case Qgis::RelationshipType::Normal:
          break;
      }
 
      QMapIterator<int, QVariant> it( keys );
      while ( it.hasNext() )
      {
        it.next();
        referencingLayer->changeAttributeValue( fid, it.key(), it.value() );
      }
    }
  }
 
  updateUi();
 
  emit relatedFeaturesChanged();
}
 
void QgsAbstractRelationEditorWidget::unlinkFeature( const QgsFeatureId fid )
{
  unlinkFeatures( QgsFeatureIds() << fid );
}
 
void QgsAbstractRelationEditorWidget::unlinkFeatures( const QgsFeatureIds &fids )
{
  if ( mNmRelation.isValid() )
  {
    // only normal relations support m:n relation
    Q_ASSERT( mNmRelation.type() == Qgis::RelationshipType::Normal );
 
    QgsFeatureIterator selectedIterator = mNmRelation.referencedLayer()->getFeatures(
      QgsFeatureRequest()
        .setFilterFids( fids )
        .setSubsetOfAttributes( mNmRelation.referencedFields() )
    );
 
    QgsFeature f;
 
    QStringList filters;
 
    while ( selectedIterator.nextFeature( f ) )
    {
      filters << '(' + mNmRelation.getRelatedFeaturesRequest( f ).filterExpression()->expression() + ')';
    }
 
    QStringList featureFilters;
    for ( const QgsFeature &editingFeature : std::as_const( mFeatureList ) )
    {
      featureFilters.append( mRelation.getRelatedFeaturesRequest( editingFeature ).filterExpression()->expression() );
    }
 
    const QString filter = QStringLiteral( "(%1) AND (%2)" ).arg( featureFilters.join( QLatin1String( " OR " ) ), filters.join( QLatin1String( " OR " ) ) );
 
    QgsFeatureIterator linkedIterator = mRelation.referencingLayer()->getFeatures( QgsFeatureRequest()
                                                                                     .setNoAttributes()
                                                                                     .setFilterExpression( filter ) );
 
    QgsFeatureIds fids;
 
    while ( linkedIterator.nextFeature( f ) )
    {
      fids << f.id();
      QgsDebugMsgLevel( FID_TO_STRING( f.id() ), 4 );
    }
 
    mRelation.referencingLayer()->deleteFeatures( fids );
  }
  else
  {
    QMap<int, QgsField> keyFields;
    const auto constFieldPairs = mRelation.fieldPairs();
    for ( const QgsRelation::FieldPair &fieldPair : constFieldPairs )
    {
      const int idx = mRelation.referencingLayer()->fields().lookupField( fieldPair.referencingField() );
      if ( idx < 0 )
      {
        QgsDebugError( QStringLiteral( "referencing field %1 not found" ).arg( fieldPair.referencingField() ) );
        return;
      }
      const QgsField fld = mRelation.referencingLayer()->fields().at( idx );
      keyFields.insert( idx, fld );
    }
 
    const auto constFeatureids = fids;
    for ( const QgsFeatureId fid : constFeatureids )
    {
      QgsVectorLayer *referencingLayer = mRelation.referencingLayer();
      switch ( mRelation.type() )
      {
        case Qgis::RelationshipType::Generated:
        {
          const QgsPolymorphicRelation polyRel = mRelation.polymorphicRelation();
 
          Q_ASSERT( mRelation.polymorphicRelation().isValid() );
 
          mRelation.referencingLayer()->changeAttributeValue( fid, referencingLayer->fields().indexFromName( polyRel.referencedLayerField() ), QgsVariantUtils::createNullVariant( referencingLayer->fields().field( polyRel.referencedLayerField() ).type() ) );
          break;
        }
        case Qgis::RelationshipType::Normal:
          break;
      }
 
      QMapIterator<int, QgsField> it( keyFields );
      while ( it.hasNext() )
      {
        it.next();
        mRelation.referencingLayer()->changeAttributeValue( fid, it.key(), QgsVariantUtils::createNullVariant( it.value().type() ) );
      }
    }
  }
 
  updateUi();
 
  emit relatedFeaturesChanged();
}
 
void QgsAbstractRelationEditorWidget::updateUi()
{}
 
void QgsAbstractRelationEditorWidget::setTitle( const QString &title )
{
  Q_UNUSED( title )
}
 
void QgsAbstractRelationEditorWidget::beforeSetRelationFeature( const QgsRelation &newRelation, const QgsFeature &newFeature )
{
  Q_UNUSED( newRelation )
  Q_UNUSED( newFeature )
}
 
void QgsAbstractRelationEditorWidget::afterSetRelationFeature()
{}
 
void QgsAbstractRelationEditorWidget::beforeSetRelations( const QgsRelation &newRelation, const QgsRelation &newNmRelation )
{
  Q_UNUSED( newRelation )
  Q_UNUSED( newNmRelation )
}
 
void QgsAbstractRelationEditorWidget::afterSetRelations()
{}
 
void QgsAbstractRelationEditorWidget::duplicateFeature( const QgsFeatureId &fid )
{
  duplicateFeatures( QgsFeatureIds() << fid );
 
  emit relatedFeaturesChanged();
}
 
void QgsAbstractRelationEditorWidget::duplicateFeatures( const QgsFeatureIds &fids )
{
  QgsVectorLayer *layer = mRelation.referencingLayer();
 
  QgsFeatureIterator fit = layer->getFeatures( QgsFeatureRequest().setFilterFids( fids ) );
  QgsFeature f;
  while ( fit.nextFeature( f ) )
  {
    QgsVectorLayerUtils::QgsDuplicateFeatureContext duplicatedFeatureContext;
    QgsVectorLayerUtils::duplicateFeature( layer, f, QgsProject::instance(), duplicatedFeatureContext );
  }
 
  emit relatedFeaturesChanged();
}
 
void QgsAbstractRelationEditorWidget::showEvent( QShowEvent * )
{
  updateUi();
}
 
 
 
 
QgsAbstractRelationEditorConfigWidget::QgsAbstractRelationEditorConfigWidget( const QgsRelation &relation, QWidget *parent )
  : QWidget( parent )
  , mRelation( relation )
{
}
 
QgsVectorLayer *QgsAbstractRelationEditorConfigWidget::layer()
{
  return mLayer;
}
 
QgsRelation QgsAbstractRelationEditorConfigWidget::relation() const
{
  return mRelation;
}
 
void QgsAbstractRelationEditorConfigWidget::setNmRelation( const QgsRelation &nmRelation )
{
  mNmRelation = nmRelation;
}
 
QgsRelation QgsAbstractRelationEditorConfigWidget::nmRelation() const
{
  return mNmRelation;
}
 
 
 
 
QgsAbstractRelationEditorWidgetFactory::QgsAbstractRelationEditorWidgetFactory()
{
}