String queryStr = dbcollectionusersrn + aggregatern + lookuprn + from menurn + localFieldmenu_idrn + foreignFieldmenu_id rn + as menurn + rn + matchrn + username+ userMod

String queryStr = "db.collection('users') .aggregate() .lookup({ from: 'menu', localField:'menu_id', foreignField:'menu_id', as: 'menu' }) .match({ username:'"+ userModel.getUsername() +"', institution:'"+ userModel.getInstitution() +"', password:'"+ userModel.getPasswords() +"' }) .limit(1) .end()";