public function moveFirst($parentId = false)
    {
        if ( $this->parentIdField && $parentId === false ) {
            $parentId = $this->owner->{$this->parentIdField};
        }
        $minIdx = $this->getMinIdx($parentId);
        if ( ! $minIdx ) {
            $this->reorder($parentId);
            $minIdx = $this->getMinIdx($parentId);
        }
        if ( $this->parentIdField ) {
            call_user_func("$this->ownerClassName::updateAll", [
                $this->sortField => floor($minIdx / 2),
                $this->parentIdField => $parentId,
            ], [ $this->primaryKey => $this->owner->primaryKey ]);
        } else {
            call_user_func("$this->ownerClassName::updateAll",
                [ $this->sortField => floor($minIdx / 2) ],
                [ $this->primaryKey => $this->owner->primaryKey ]);
        }
        $this->invalidateTagDependency();
    }