Item::readValueFromDatabase

public function readValueFromDatabase($key, $item)
{
	$id = $item->getId();
	if($id)
	{
		/** @var BitrixTasksItem|BitrixTasksItemSubItem $itemClass */
		$itemClass = static::getItemClass();
		if(method_exists($itemClass, 'findByParent')) // todo: use SubItem::isA() here, when moved to 5.4
		{
			$value = $itemClass::findByParent($id, array(), array('USER_ID' => $item->getUserId()));
		}
		else
		{
			throw new ArgumentTypeException('There should be a sub-item class: '.$key);
		}
	}
	else
	{
		$value = array();
	}

	return $this->translateValueFromDatabase($value, $key, $item);
}