db={"workoutDetailSchema":[{"_id":{"$oid":"6359a12fb9450da3d8d8cdd2"},"REF_Users":[{"$oid":"6359a0f1b9450da3d8d8cdc7"},{"$oid":"6359a070f1e84209e0c78fc2"}],"name":"Once"}],"users":[{"_id":{"$oid":"6359a070f1e84209e0c78fc2"},"REF_UserType":{"$oid":"63596323b679475de490500a"},"fName":"Billy"},{"_id":{"$oid":"6359a0f1b9450da3d8d8cdc7"},"REF_UserType":{"$oid":"63596323b679475de4905007"},"fName":"Mike"}],"usertypes":[{"_id":{"$oid":"63596323b679475de4905007"},"value":100,"name":"INS"},{"_id":{"$oid":"63596323b679475de490500a"},"value":200,"name":"CLS"}]}

db.workoutDetailSchema.aggregate([{"$lookup":{"from":"users","localField":"REF_Users","foreignField":"_id","pipeline":[{"$lookup":{"from":"usertypes","localField":"REF_UserType","foreignField":"_id","pipeline":[{$limit:1}],"as":"userType"}},{"$unwind":"$userType"}],"as":"people"}}])