Model::save

public function save($onlyCheck = false)
{
	/* @var $class \Bitrix\Main\Entity\DataManager */
	$class = $this->getClassTable();

	$this->errors = array();
	$fields = $this->params;

	if($onlyCheck)
	{
		$result = new EntityResult;
		$class::checkFields($result, $this->id, $fields);
		$this->prepareResult($result);

		return;
	}

	if(!$this->check())
	{
		return;
	}

	if($this->id)
	{
		$result = $class::update($this->id, $fields);
	}
	else
	{
		$result = $class::add($fields);
		$this->id = $result->getId();
	}

	$this->prepareResult($result);
}