我在SpagoBI下使用groovy脚本。我想使用聚合。例如，我想执行以下聚合:db.myCollection.aggregate([{$group:{_id:{day:{$dayOfMonth:"$recvTime"}}}}])我试过了:DBObjectprojectFields=newBasicDBObject('$dayOfMonth',"recvTime");DBObjectproject=newBasicDBObject('$project',projectFields)DBObjectgroupFields=newBasicDBObject("_id",project);D