Database
[{supplier:1,type:"sale",items:[{"_id":ObjectId("60ee82dd2131c5032342070f"),"itemBuySum":10},{"_id":ObjectId("60ee82dd2131c50323420710"),"itemBuySum":10,},{"_id":ObjectId("60ee82dd2131c50323420713"),"itemBuySum":10},{"_id":ObjectId("60ee82dd2131c50323420714"),"itemBuySum":20}]},{supplier:1,type:"sale",items:[{"_id":ObjectId("60ee82dd2131c5032342070f"),"itemBuySum":20},{"_id":ObjectId("60ee82dd2131c50323420714"),"itemBuySum":20}]},{supplier:1,type:"return",items:[{"_id":ObjectId("60ee82dd2131c5032342070f"),"itemBuySum":100},{"_id":ObjectId("60ee82dd2131c50323420714"),"itemBuySum":70}]}]
Query
db.collection.aggregate({$match:{supplier:1},})