node.js - Not sure how to return endpoint -

i have node/express api not sure how return results of $group.

my code:

router.route('/viewed_card/:invite_id')     .get(function(req, res){      profile.aggregate([             {$unwind:'$contacts'},             {$unwind:'$contacts.shared'},             {$match:{'contacts.shared.invite_id':req.params.invite_id}},             {$group:{                 _id:null,                 first_name:{$first:'$contacts.first_name'},                 last_name:{$first:'$contacts.last_name'}             }}         ])      }) 

how return results?

i tried doing "return" before "profile.aggregate" function.

i though maybe this:

router.route('/viewed_card/:invite_id')     .get(function(req, res){      profile.aggregate([             {$unwind:'$contacts'},             {$unwind:'$contacts.shared'},             {$match:{'contacts.shared.invite_id':req.params.invite_id}},             {$group:{                 _id:null,                 first_name:{$first:'$contacts.first_name'},                 last_name:{$first:'$contacts.last_name'}             }}         ], function(err, result){             return result;         }      }) 

but nothing...

if not wrong aggregation returns promise, can try way

var profile=profile.aggregate([     {$unwind:'$contacts'},     {$unwind:'$contacts.shared'},     {$match:{'contacts.shared.invite_id':req.params.invite_id}},     {$group:{         _id:null,         first_name:{$first:'$contacts.first_name'},         last_name:{$first:'$contacts.last_name'}     }} ]);  profile.then((data) => {     res.status(200).jsonp({         data     }); }) .catch(err => {     res.status(422).jsonp({errors: err}); });  

or can use cursor

profile.aggregate([     {$unwind:'$contacts'},     {$unwind:'$contacts.shared'},     {$match:{'contacts.shared.invite_id':req.params.invite_id}},     {$group:{         _id:null,         first_name:{$first:'$contacts.first_name'},         last_name:{$first:'$contacts.last_name'}     }} ]).toarray(function(err, results) {     if(!err) res.status(200).jsonp(agenodes);     else res.status(422).jsonp(err); });