polymorphic Closure Table Extension

example.php

<?php

use \Franzose\ClosureTable\Models\Entity  as ClosureEntity;

Class PolyClosureModel extends ClosureEntity {

    protected $rootKey;

    public function getDescendants(array $columns = ['*'])
    {
        return $this->joinClosureBy('descendant')->get($columns);
    }

    protected function getRelatedTables($rootElement) {

        $modelTypes = \DB::table('content')
            ->select('content.content_type')
            ->distinct()
            ->join('content_closure', 'content.id', '=', 'content_closure.descendant')
            ->where('content_closure.ancestor','=',$rootElement)
            ->lists('content_type');

        $joins = $this;

        foreach ($modelTypes as $type) {

            $joins = $joins
                ->leftJoin('content_'. strtolower($type), function ($join) use ($type) {
                    $join
                        ->on('content.content_id', '=', 'content_'. strtolower($type).'.id')
                        ->on('content.content_type','=',\DB::raw("'$type'"));
                });
        }
        return $joins;
    }

    protected function joinClosureBy($column, $withSelf = true)
    {

        $primary    = $this->getQualifiedKeyName();
        $closure    = $this->closure->getTable();
        $ancestor   = $this->closure->getQualifiedAncestorColumn();
        $descendant = $this->closure->getQualifiedDescendantColumn();

        $this->rootKey = $this->getKey();

        $query = $this->getRelatedTables($this->rootKey);

        switch($column)
        {
            case 'ancestor':
                $query = $query->join($closure, $ancestor, '=', $primary)
                    ->where($descendant, '=', $this->rootKey);
                break;

            case 'descendant':
                $query = $query->join($closure, $descendant, '=', $primary)
                    ->where($ancestor, '=', $this->rootKey);
                break;
        }

        $depthOperator = ($withSelf === true ? '>=' : '>');

        $query->where($this->closure->getQualifiedDepthColumn(), $depthOperator, 0);

        return $query;
    }
}