db={"projects":[{"_id":1,"name":"us project","projectmembers":[{"_id":1,"name":"Vikash","present":true},{"_id":2,"name":"Priyanshu","present":true}]}]}

db.projects.aggregate([{$project:{_id:0,projectmembers:{$filter:{input:"$projectmembers",as:"projectMember",cond:{$eq:["$$projectMember._id",2]}}}}}])