ElementV2::sysSaveRelations

public function sysSaveRelations(Result $result)
{
	parent::sysSaveRelations($result);

	// by default property references are not handled
	// we can collect them here and compose into one sql query
	// and mark them as ACTUAL after query

	/** @var EntityObject[] $valueObjects objects to save */
	$valueObjects = [];

	// compose data for update query
	$valuesToDb = [];

	foreach ($this->entity->getFields() as $field)
	{
		if ($field instanceof PropertyReference)
		{
			// save single value references
			if ($this->has($field->getName()))
			{
				$valueObject = $this->get($field->getName());

				if ($valueObject->state == State::RAW || $valueObject->state == State::CHANGED)
				{
					$valueObjects[$field->getName()] = $valueObject;
				}
			}
		}
		elseif ($field instanceof PropertyOneToMany && $this->state === State::CHANGED)
		{
			// clear serialized multiple value cache
			$columnName = 'PROPERTY_'.$field->getIblockElementProperty()->getId();
			$valuesToDb[$columnName] = null;
		}
	}

	foreach ($valueObjects as $valueObject)
	{
		// collect changed values and descriptions from all the objects
		if ($valueObject->isChanged('VALUE'))
		{
			$columnName = $valueObject->entity->getField('VALUE')->getColumnName();
			$valuesToDb[$columnName] = $valueObject->get('VALUE');
		}

		if ($valueObject->entity->hasField('DESCRIPTION') && $valueObject->isChanged('DESCRIPTION'))
		{
			$columnName = $valueObject->entity->getField('DESCRIPTION')->getColumnName();
			$valuesToDb[$columnName] = $valueObject->get('DESCRIPTION');
		}
	}

	if (!empty($valuesToDb))
	{
		// execute update
		$connection = $this->entity->getConnection();
		$helper = $connection->getSqlHelper();

		$tableName = $this->entity->getSingleValueTableName();
		$update = $helper->prepareUpdate($tableName, $valuesToDb);
		$where = $helper->prepareAssignment($tableName, 'IBLOCK_ELEMENT_ID', $this->getId());

		$sql = "UPDATE ".$helper->quote($tableName)." SET ".$update[0]." WHERE ".$where;
		$connection->queryExecute($sql, $update[1]);
	}

	// get current values and set them as actual
	foreach ($valueObjects as $fieldName => $valueObject)
	{
		$currentValues = $valueObject->collectValues(Values::CURRENT);

		foreach ($currentValues as $propFieldName => $propFieldValue)
		{
			$valueObject->sysSetActual($propFieldName, $propFieldValue);
		}

		$valueObject->sysPostSave();
	}
}