Product constructor doesn't work

[eggwane]

Hello,

I'm trying to build a function which returns a string with products' url for a specific Manufacturer. Here is my code in ManufacturerController.php :

static public function getProductsImgToDisplay($id_manufacturer){
	    global $cookie;
	    $sql ="select id_product from "._DB_PREFIX_."product where id_manufacturer=".$id_manufacturer.";";
	    $sql_output = Db::getInstance()->ExecuteS($sql);
	    $output = ""; 
	    foreach ($sql_output as $row){
		    $id_product = $row["id_product"];
		    $product = new Product(id_product, false, $cookie->id_lang);
			//$img = $product->getCover($product->id);
		    //$img_url =$this->context->link->getImageLink($product->link_rewrite, (int)$img['id_image'], 'small_default');
		    $output .= $id_product."-";
		    $output .= $product->id."\n";
	    }
	    return $sql."->".$output."|";
	}

Here I'm just testing if the variable $product is well defined but it seems to not work because I have this output for example :

select id_product from ps_product where id_manufacturer=890;->4707- 4708- 4717- 4718- 5311- 5312- 5483- 5503- |

The sql resquest worked and the ids are good but it seems that the constructor Product doesnt build correctly the $product variable?

Thanks for your help :)