collection sample

<?php
namespace GK\Collections;


use GK\Container;
use GK\Entities\Product;
use GK\entities\Size;

class ProductCollection extends \ArrayObject
{

    /**
     * @param null $limit
     * @param null $offset
     * @return self
     */
    public static function fetchAll($limit=null, $offset=null) {
        if  ($limit !== null && !is_numeric($limit)) {
            $limit = NULL;
        }
        if  ($offset !==NULL && !is_numeric($offset)) {
            $offset = NULL;
        }
        $Select = Container::getInst()->qbf->newSelect()
            ->cols([
                'id','brand','name','url','price_usd','description',
                'picture1','picture2','picture3','picture4','picture5',
            ])
            ->from('products p');
        if ($limit) {
            $Select->limit($limit);
        }
        if ($offset) {
            $Select->offset($offset);
        }
        $products = Container::getInst()->db->fetchAll($Select);
        $count = sizeof($products);
        $Collection = new self($count);

        $Select = Container::getInst()->qbf->newSelect()
            ->cols(['product_id','size_eur','size_us','size_ru',])
            ->from('sizes');
        //$st = Container::getInst()->db->perform($Select);
        $sizes = Container::getInst()->db->perform($Select)
            ->fetchAll(
                \PDO::FETCH_CLASS | \PDO::FETCH_GROUP,
                Size::class
            );

        for ($i=0;$i<$count;++$i) {
            $P = new Product();
            $P->setAttributes($products[$i]);
            if (isset($sizes[$P->id])){
                $P->setSizes(SizeCollection::fromArray($sizes[$P->id]));
            }
            $Collection->offsetSet($i,$P);
        }
        return $Collection;
    }
}