qgsvectorlayereditbuffergroup.cpp

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/***************************************************************************
  qgsvectorlayereditbuffergroup.cpp - QgsVectorLayerEditBufferGroup
 
 ---------------------
 begin                : 22.12.2021
 copyright            : (C) 2021 by Damiano Lombardi
 email                : damiano@opengis.ch
 ***************************************************************************
 *                                                                         *
 *   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 "qgsvectorlayereditbuffergroup.h"
 
#include "qgsproject.h"
#include "qgstransaction.h"
#include "qgsvectorlayer.h"
#include "qgsvectorlayereditbuffer.h"
 
#include <QQueue>
 
#include "moc_qgsvectorlayereditbuffergroup.cpp"
 
QgsVectorLayerEditBufferGroup::QgsVectorLayerEditBufferGroup( QObject *parent )
  : QObject( parent )
{}
 
void QgsVectorLayerEditBufferGroup::addLayer( QgsVectorLayer *layer )
{
  mLayers.insert( layer );
}
 
void QgsVectorLayerEditBufferGroup::removeLayer( QgsVectorLayer *layer )
{
  mLayers.remove( layer );
}
 
void QgsVectorLayerEditBufferGroup::clear()
{
  mLayers.clear();
}
 
QSet<QgsVectorLayer *> QgsVectorLayerEditBufferGroup::layers() const
{
  return mLayers;
}
 
QSet<QgsVectorLayer *> QgsVectorLayerEditBufferGroup::modifiedLayers() const
{
  QSet<QgsVectorLayer *> modifiedLayers;
 
  for ( QgsVectorLayer *layer : std::as_const( mLayers ) )
    if ( layer->isModified() )
      modifiedLayers.insert( layer );
 
  return modifiedLayers;
}
 
bool QgsVectorLayerEditBufferGroup::startEditing()
{
  if ( mIsEditing )
    return true;
 
  bool editingStarted = true;
  for ( QgsVectorLayer *layer : std::as_const( mLayers ) )
  {
    if ( !layer->isValid() )
    {
      editingStarted = false;
      QgsLogger::debug( tr( "Can't start editing invalid layer '%1'." ).arg( layer->name() ) );
      break;
    }
 
    if ( !layer->dataProvider() )
    {
      editingStarted = false;
      QgsLogger::debug( tr( "Can't start editing layer '%1' with invalid data provider." ).arg( layer->name() ) );
      break;
    }
 
    // allow editing if provider supports any of the capabilities
    if ( !layer->supportsEditing() )
    {
      editingStarted = false;
      QgsLogger::debug( tr( "Can't start editing. Layer '%1' doesn't support editing." ).arg( layer->name() ) );
      break;
    }
 
    if ( layer->editBuffer() )
    {
      // editing already underway
      layer->editBuffer()->setEditBufferGroup( this );
      continue;
    }
 
 
    emit layer->beforeEditingStarted();
    layer->dataProvider()->enterUpdateMode();
    layer->createEditBuffer();
    layer->editBuffer()->setEditBufferGroup( this );
    layer->updateFields();
    emit layer->editingStarted();
  }
 
  if ( !editingStarted )
  {
    QStringList rollbackErrors;
    if ( !rollBack( rollbackErrors, true ) )
      QgsLogger::debug( tr( "Can't rollback after start editing failure. Roll back detailed errors: %1" ).arg( rollbackErrors.join( " / " ) ) );
  }
 
  mIsEditing = editingStarted;
  return mIsEditing;
}
 
bool QgsVectorLayerEditBufferGroup::commitChanges( QStringList &commitErrors, bool stopEditing )
{
  bool success = true;
 
  const QSet<QgsVectorLayer *> constModifiedLayers = modifiedLayers();
 
  if ( constModifiedLayers.isEmpty() )
  {
    editingFinished( stopEditing );
    mIsEditing = !stopEditing;
    return success;
  }
 
  // trigger geometry checks for all the modified layers
  for ( QgsVectorLayer *modifiedLayer : constModifiedLayers )
  {
    emit modifiedLayer->beforeCommitChecks( stopEditing );
  }
 
  // and if at least one does not allow commit, return
  for ( const QgsVectorLayer *modifiedLayer : constModifiedLayers )
  {
    if ( !modifiedLayer->allowCommit() )
    {
      commitErrors << tr( "ERROR: Commit not allowed because of failed checks." );
      return false;
    }
  }
 
  QMap<QString, QSet<QgsVectorLayer *> > connectionStringsLayers;
  for ( QgsVectorLayer *modifiedLayer : constModifiedLayers )
    if ( QgsTransaction::supportsTransaction( modifiedLayer ) )
      connectionStringsLayers[QgsTransaction::connectionString( modifiedLayer->source() )].insert( modifiedLayer );
 
  QList<QgsVectorLayer *> transactionLayers;
  QList<std::shared_ptr<QgsTransaction> > openTransactions;
  const QStringList connectionStrings = connectionStringsLayers.keys();
  for ( const QString &connectionString : connectionStrings )
  {
    const QString providerKey = ( *connectionStringsLayers.value( connectionString ).begin() )->providerType();
 
    std::shared_ptr<QgsTransaction> transaction;
    transaction.reset( QgsTransaction::create( connectionString, providerKey ) );
    if ( !transaction )
    {
      commitErrors << tr( "ERROR: data source '%1', is not available for transactions." ).arg( connectionString );
      success = false;
      break;
    }
 
    QString errorMsg;
    if ( !transaction->begin( errorMsg ) )
    {
      commitErrors << tr( "ERROR: could not start a transaction on data provider '%1', detailed error: '%2'." ).arg( providerKey, errorMsg );
      success = false;
      break;
    }
 
    const auto constLayers = connectionStringsLayers.value( connectionString );
    for ( QgsVectorLayer *layer : constLayers )
    {
      if ( !transaction->addLayer( layer, true ) )
      {
        commitErrors << tr( "ERROR: could not add layer '%1' to transaction on data provider '%2'." ).arg( layer->name(), providerKey );
        success = false;
        break;
      }
 
      transactionLayers.append( layer );
    }
 
    openTransactions.append( transaction );
 
    if ( !success )
      break;
  }
 
  // Order layers children to parents
  const QList<QgsVectorLayer *> orderedLayers = orderLayersParentsToChildren( constModifiedLayers );
  QList<QgsVectorLayer *>::const_iterator orderedLayersIterator;
 
  // Check geometry types
  if ( success )
  {
    for ( orderedLayersIterator = orderedLayers.constBegin(); orderedLayersIterator != orderedLayers.constEnd(); ++orderedLayersIterator )
    {
      if ( !( *orderedLayersIterator )->editBuffer() )
      {
        commitErrors << tr( "ERROR: edit buffer of layer '%1' is not valid." ).arg( ( *orderedLayersIterator )->name() );
        success = false;
        break;
      }
 
      success = ( *orderedLayersIterator )->editBuffer()->commitChangesCheckGeometryTypeCompatibility( commitErrors );
      if ( !success )
        break;
    }
  }
 
  QSet<QgsVectorLayer *> modifiedLayersOnProviderSide;
 
  // Change fields (add new fields, delete fields)
  if ( success )
  {
    for ( orderedLayersIterator = orderedLayers.constBegin(); orderedLayersIterator != orderedLayers.constEnd(); ++orderedLayersIterator )
    {
      QgsFields oldFields = ( *orderedLayersIterator )->fields();
 
      bool attributesDeleted = false;
      success = ( *orderedLayersIterator )->editBuffer()->commitChangesDeleteAttributes( attributesDeleted, commitErrors );
      if ( !success )
        break;
 
      bool attributesRenamed = false;
      success = ( *orderedLayersIterator )->editBuffer()->commitChangesRenameAttributes( attributesRenamed, commitErrors );
      if ( !success )
        break;
 
      bool attributesAdded = false;
      success = ( *orderedLayersIterator )->editBuffer()->commitChangesAddAttributes( attributesAdded, commitErrors );
      if ( !success )
        break;
 
      if ( attributesDeleted || attributesRenamed || attributesAdded )
      {
        if ( !transactionLayers.contains( ( *orderedLayersIterator ) ) )
          modifiedLayersOnProviderSide.insert( ( *orderedLayersIterator ) );
 
        success = ( *orderedLayersIterator )->editBuffer()->commitChangesCheckAttributesModifications( oldFields, commitErrors );
        if ( !success )
          break;
      }
    }
  }
 
  // delete all features, in reverse dependency order (children first)
  if ( success )
  {
    orderedLayersIterator = orderedLayers.constEnd();
    while ( orderedLayersIterator != orderedLayers.constBegin() )
    {
      --orderedLayersIterator;
      bool featuresDeleted;
      success = ( *orderedLayersIterator )->editBuffer()->commitChangesDeleteFeatures( featuresDeleted, commitErrors );
      if ( !success )
        break;
 
      if ( featuresDeleted && transactionLayers.contains( ( *orderedLayersIterator ) ) )
        modifiedLayersOnProviderSide.insert( ( *orderedLayersIterator ) );
    }
  }
 
  // add all features, in forward dependency order (parents first)
  if ( success )
  {
    for ( orderedLayersIterator = orderedLayers.constBegin(); orderedLayersIterator != orderedLayers.constEnd(); ++orderedLayersIterator )
    {
      bool featuresAdded;
      success = ( *orderedLayersIterator )->editBuffer()->commitChangesAddFeatures( featuresAdded, commitErrors );
      if ( !success )
        break;
 
      if ( featuresAdded && transactionLayers.contains( ( *orderedLayersIterator ) ) )
        modifiedLayersOnProviderSide.insert( ( *orderedLayersIterator ) );
    }
  }
 
  // change all attributes and geometries in reverse dependency order (children first)
  if ( success )
  {
    orderedLayersIterator = orderedLayers.constEnd();
    while ( orderedLayersIterator != orderedLayers.constBegin() )
    {
      --orderedLayersIterator;
 
      bool attributesChanged;
      success = ( *orderedLayersIterator )->editBuffer()->commitChangesChangeAttributes( attributesChanged, commitErrors );
      if ( !success )
        break;
 
      if ( attributesChanged && transactionLayers.contains( ( *orderedLayersIterator ) ) )
        modifiedLayersOnProviderSide.insert( ( *orderedLayersIterator ) );
    }
  }
 
  // if everything went well, commit
  if ( success )
  {
    QList<std::shared_ptr<QgsTransaction> >::iterator openTransactionsIterator = openTransactions.begin();
    while ( openTransactionsIterator != openTransactions.end() )
    {
      QString errorMsg;
      if ( !( *openTransactionsIterator )->commit( errorMsg ) )
      {
        success = false;
        commitErrors << tr( "ERROR: could not commit a transaction, detailed error: '%1'." ).arg( errorMsg );
        break;
      }
 
      modifiedLayersOnProviderSide += connectionStringsLayers.value( ( *openTransactionsIterator )->connectionString() );
      openTransactionsIterator = openTransactions.erase( openTransactionsIterator );
    }
  }
 
  // Otherwise rollback
  if ( !success )
  {
    // Append additional information about layer which can't be rollbacked
    if ( !modifiedLayersOnProviderSide.isEmpty() )
    {
      if ( modifiedLayersOnProviderSide.size() == 1 )
        commitErrors << tr( "WARNING: changes to layer '%1' were already sent to data provider and cannot be rolled back." ).arg( ( *modifiedLayersOnProviderSide.begin() )->name() );
      else
      {
        commitErrors << tr( "WARNING: changes to following layers were already sent to data provider and cannot be rolled back:" );
        for ( QgsVectorLayer *layer : std::as_const( modifiedLayersOnProviderSide ) )
          commitErrors << tr( "- '%1'" ).arg( layer->name() );
      }
    }
 
    QString rollbackError;
    for ( const std::shared_ptr<QgsTransaction> &transaction : openTransactions )
      transaction->rollback( rollbackError );
  }
 
  // Stop editing
  if ( success )
    editingFinished( stopEditing );
 
  if ( success && stopEditing )
    mIsEditing = false;
 
  return success;
}
 
bool QgsVectorLayerEditBufferGroup::rollBack( QStringList &rollbackErrors, bool stopEditing )
{
  for ( QgsVectorLayer *layer : std::as_const( mLayers ) )
  {
    if ( !layer->editBuffer() )
      continue;
 
    if ( !layer->dataProvider() )
    {
      rollbackErrors << tr( "Layer '%1' doesn't have a valid data provider" ).arg( layer->name() );
      return false;
    }
 
    bool rollbackExtent = !layer->editBuffer()->deletedFeatureIds().isEmpty() || !layer->editBuffer()->addedFeatures().isEmpty() || !layer->editBuffer()->changedGeometries().isEmpty();
 
    emit layer->beforeRollBack();
 
    layer->editBuffer()->rollBack();
 
    emit layer->afterRollBack();
 
    if ( layer->isModified() )
    {
      // new undo stack roll back method
      // old method of calling every undo could cause many canvas refreshes
      layer->undoStack()->setIndex( 0 );
    }
 
    layer->updateFields();
 
    if ( stopEditing )
    {
      layer->clearEditBuffer();
      layer->undoStack()->clear();
      emit layer->editingStopped();
    }
 
    if ( rollbackExtent )
      layer->updateExtents();
 
    if ( stopEditing )
      layer->dataProvider()->leaveUpdateMode();
 
    layer->triggerRepaint();
  }
 
  mIsEditing = !stopEditing;
  return true;
}
 
bool QgsVectorLayerEditBufferGroup::isEditing() const
{
  return mIsEditing;
}
 
QList<QgsVectorLayer *> QgsVectorLayerEditBufferGroup::orderLayersParentsToChildren( QSet<QgsVectorLayer *> layers )
{
  QList<QgsVectorLayer *> orderedLayers;
  QSet<QgsVectorLayer *> unorderedLayers = layers;
 
  bool layerOrdered = true;
  while ( !unorderedLayers.isEmpty() && layerOrdered )
  {
    layerOrdered = false;
    QSet<QgsVectorLayer *>::iterator unorderedLayerIterator = unorderedLayers.begin();
    while ( unorderedLayerIterator != unorderedLayers.end() )
    {
      // TODO QGIS 5.0 -- if layer has no associated project, return empty list of referencing relations insted of getting it from project instance
      // Get referencing relation to find referenced layers
      const QList<QgsRelation> referencingRelations = !layers.empty() && *layers.constBegin()
                                                        ? ( *layers.constBegin() )->project()->relationManager()->referencingRelations( *unorderedLayerIterator )
                                                        : QgsProject::instance()->relationManager()->referencingRelations( *unorderedLayerIterator ); // skip-keyword-check
 
      // If this layer references at least one modified layer continue
      bool layerReferencingModifiedLayer = false;
      for ( const QgsRelation &relation : referencingRelations )
      {
        if ( unorderedLayers.contains( relation.referencedLayer() ) )
        {
          layerReferencingModifiedLayer = true;
          break;
        }
      }
      if ( layerReferencingModifiedLayer )
      {
        ++unorderedLayerIterator;
        continue;
      }
 
      // No modified layer is referencing this layer
      orderedLayers.append( *unorderedLayerIterator );
      unorderedLayerIterator = unorderedLayers.erase( unorderedLayerIterator );
      layerOrdered = true;
    }
  }
 
  if ( !unorderedLayers.isEmpty() )
  {
    QgsLogger::warning( tr( "Circular relation between some layers. Correct saving order of layers can't be guaranteed" ) );
    orderedLayers.append( unorderedLayers.values() );
  }
 
  return orderedLayers;
}
 
void QgsVectorLayerEditBufferGroup::editingFinished( bool stopEditing )
{
  for ( QgsVectorLayer *layer : std::as_const( mLayers ) )
  {
    if ( !layer->mDeletedFids.empty() )
    {
      emit layer->featuresDeleted( layer->mDeletedFids );
      layer->mDeletedFids.clear();
    }
 
    if ( stopEditing )
      layer->clearEditBuffer();
 
    layer->undoStack()->clear();
    emit layer->afterCommitChanges();
    if ( stopEditing )
      emit layer->editingStopped();
 
    layer->updateFields();
 
    layer->dataProvider()->updateExtents();
 
    if ( stopEditing )
    {
      layer->dataProvider()->leaveUpdateMode();
    }
 
    // This second call is required because OGR provider with JSON
    // driver might have changed fields order after the call to
    // leaveUpdateMode
    if ( layer->fields().names() != layer->dataProvider()->fields().names() )
    {
      layer->updateFields();
    }
 
    layer->triggerRepaint();
  }
}