[{item:"banana",price:"2$",order_type:"INTERNATIONAL"/** There are 2 types: INTERNATIONAL and MAINLAND*/},{item:"banana",price:"2$",order_type:"N"/** There are 2 types: INTERNATIONAL and MAINLAND*/}]

db.collection.aggregate([{$group:{_id:"$order_type",nbOfOrders:{$sum:1}}},{"$group":{"_id":null,"orderTypeCount":{"$push":"$$ROOT"}}},{$project:{"_id":0}}])