UI mongo group report

ui ： default with cost total

db.adnstats.aggregate([{$group : {_id : {"ProductId":"$ProductId","ProjectId":"$ProjectId"},"GroupId":{$addToSet : "$GroupId"}, group_total : {$sum : 1},request_total : {$sum : "$Request"},ImpNormal_total : {$sum : "$ImpNormal"},ClNormal_total : {$sum : "$ClNormal"},ClkInvalid_total : {$sum : "$ClkInvalid"},Cost_total : {$sum : "$Cost"}}}])

ui : default with cost and Date group 

(why date group fails ?)

db.adnstats.aggregate([{$group : {_id : {"ProductId":"$ProductId","ProjectId":"$ProjectId","Date":"2017-08-31"},"GroupId":{$addToSet : "$GroupId"}, group_total : {$sum : 1},request_total : {$sum : "$Request"},ImpNormal_total : {$sum : "$ImpNormal"},ClNormal_total : {$sum : "$ClNormal"},ClkInvalid_total : {$sum : "$ClkInvalid"},Cost_total : {$sum : "$Cost"}}}])