private function _getProductIdBySlug($slug)
{
$slugAttribute = ProductAttribute::where('identifier', '=', 'slug')->get()->first();
$productVarcharValue = ProductVarcharValue::where('product_attribute_id', '=', $slugAttribute->id)->where('value', '=', $slug)->where('website_id', '=', $this->websiteId)->get()->first();
return $productVarcharValue->product_id;
}