[{"_id":ObjectId("5fca982d219fee6f00e631a0"),"price":45.9,"createdAt":ISODate("2020-12-04T20:12:29.117Z")},{"_id":ObjectId("5fca990b219fee6f00e631a1"),"price":45.9,"createdAt":ISODate("2020-12-04T20:16:11.925Z")},{"_id":ObjectId("5fcab925a912a2064fe7b916"),"price":45.9,"createdAt":ISODate("2020-12-04T22:33:09.958Z")},{"_id":ObjectId("5fcab938a912a2064fe7b917"),"price":45.9,"createdAt":ISODate("2020-12-04T22:33:28.641Z")},{"_id":ObjectId("5fcab94aa912a2064fe7b918"),"createdAt":ISODate("2020-12-04T22:33:46.118Z")},{"_id":ObjectId("5fcb73e0e396cf18e6141dc6"),"price":45.9,"createdAt":ISODate("2020-12-05T11:49:52.544Z")},{"_id":ObjectId("5fcb73eee396cf18e6141dc7"),"price":45.9,"createdAt":ISODate("2020-12-05T11:50:06.914Z")},{"_id":ObjectId("5fcbee785ef206248fa9513e"),"price":35.7,"createdAt":ISODate("2020-12-05T20:32:56.508Z")},{"_id":ObjectId("5fcbf0045ef206248fa9513f"),"price":2047.66,"createdAt":ISODate("2020-12-05T20:39:32.369Z")}]

db.collection.aggregate([{$group:{_id:{$week:"$createdAt"},totalPrice:{$sum:"$price"}}}])