db={"chats":[{"_id":ObjectId("6000cb3a7ca86a96c13bada8"),"clients":[{"email":"2222@mail.id","_id":ObjectId("6000cb3a7ca86a96c13bada9"),"id":2222,"as":"owner","username":"2222","phonenumber":"1111"},{"email":"1111@mail.id","_id":ObjectId("6000cb3a7ca86a96c13badaa"),"id":1111,"as":"user","username":"1111","phonenumber":"1111"}],"roomId":"6","createdAt":ISODate("2021-01-14T22:52:42.357Z"),"updatedAt":ISODate("2021-01-14T22:52:42.357Z"),"__v":0}],"messages":[{"_id":ObjectId("6000cb3a7ca86a96c13badab"),"status":"SEND","roomId":ObjectId("6000cb3a7ca86a96c13bada8"),"text":"Hellw as a user here","senderId":2222,"receiverId":1111,"createdAt":ISODate("2021-01-14T22:52:42.365Z"),"updatedAt":ISODate("2021-01-14T22:52:42.365Z"),"__v":0,},{"_id":ObjectId("6000cb457ca86a96c13badac"),"status":"SEND","roomId":ObjectId("6000cb3a7ca86a96c13bada8"),"text":"Hellow I'm onwer too guyy","senderId":1111,"receiverId":2222,"createdAt":ISODate("2021-01-14T22:52:53.596Z"),"updatedAt":ISODate("2021-01-14T22:52:53.596Z"),"__v":0}]}

db.messages.aggregate([{$lookup:{from:"chats",/** $roomId are field from messages*/let:{roomId:"$roomId"},/** $_id are field from chats*/pipeline:[{$match:{$expr:{$and:[{$eq:["$_id","$$roomId"]},{$eq:["$clients.id",1111]},{$eq:["$clients.as","user"]},],},},},],as:"chat_room",},},])