[{"ProjectName":"PROJECT-AA","PartnerName":"PART-AA","Date":"2021-01-01","Time":"21:00:00"},{"ProjectName":"PROJECT-AA","PartnerName":"PART-AA","Date":"2021-01-01","Time":"21:00:00"},{"ProjectName":"PROJECT-AA","PartnerName":"PART-AA","Date":"2021-01-03","Time":"23:00:00"},{"ProjectName":"PROJECT-AA","PartnerName":"PART-BB","Date":"2021-01-03","Time":"23:00:00"},{"ProjectName":"PROJECT-AA","PartnerName":"PART-BB","Date":"2021-01-03","Time":"23:00:00"},{"ProjectName":"PROJECT-AA","PartnerName":"PART-BB","Date":"2021-01-03","Time":"23:00:00"},{"ProjectName":"PROJECT-BB","PartnerName":"PART-AA","Date":"2021-01-01","Time":"21:00:00"},{"ProjectName":"PROJECT-BB","PartnerName":"PART-AA","Date":"2021-01-01","Time":"21:00:00"},{"ProjectName":"PROJECT-BB","PartnerName":"PART-AA","Date":"2021-01-03","Time":"23:00:00"},{"ProjectName":"PROJECT-BB","PartnerName":"PART-BB","Date":"2021-01-01","Time":"21:00:00"},{"ProjectName":"PROJECT-BB","PartnerName":"PART-BB","Date":"2021-01-02","Time":"22:00:00"},{"ProjectName":"PROJECT-BB","PartnerName":"PART-BB","Date":"2021-01-02","Time":"23:00:00"},]

db.collection.aggregate([{"$group":{"_id":{"ProjectName":"$ProjectName","PartnerName":"$PartnerName","Date":"$Date"},Time:{$push:"$Time"}}},{"$group":{"_id":{"ProjectName":"$_id.ProjectName","PartnerName":"$_id.PartnerName"},DateTime:{$push:{Date:"$_id.Date",Time:"$Time"}}}},{"$group":{"_id":"$_id.ProjectName",partner:{$push:{PartnerName:"$_id.PartnerName",DateTime:"$DateTime"}}}}])