Database
[{"_id":{"$oid":"5e34522580e513373d96112b"},"productId":{"$oid":"5e345223b3aa703b8a9a4f34"},"createdAt":{"$date":"2018-03-04T06:19:36.346Z"},},{"_id":{"$oid":"5e34522580e513373d9611e3"},"productId":{"$oid":"5e345223b3aa703b8a9a4f34"},"createdAt":{"$date":"2018-03-04T06:19:36.346Z"},},{"_id":{"$oid":"5e34522580e513373d9611fa"},"productId":{"$oid":"5e345223b3aa703b8a9a4f35"},"createdAt":{"$date":"2018-03-04T06:19:36.346Z"},},{"_id":{"$oid":"5e34522580e513373d96123c"},"productId":{"$oid":"5e345223b3aa703b8a9a4f35"},"createdAt":{"$date":"2018-03-04T06:19:36.346Z"},}]
Query
db.collection.aggregate({})