rating all

$lookup:{
                from:"reviewlocations",
                localField:"_id",
                foreignField:"id_location",
                as: "list_rating"
            }
$project:{

	"rating_all":{
    	          $avg: "$list_rating.rating"
 	}
}


			if(result[i].rating_all == null){
                result[i].rating_all = "0"
            }else{
                result[i].rating_all = String(result[i].rating_all)
            }