SubItem::getParent

public function getParent()
{
	if($this->parent)
	{
		return $this->parent;
	}
	else
	{
		// we can fetch parent if we know its ID
		$parentId = $this->getParentId();
		if($parentId)
		{
			$parentClass = static::getParentClass();
			$parent = new $parentClass($parentId);

			$this->parent = $parent;

			return $parent;
		}
	}

	return null;
}