Simple promise with forEach

You are returning a deferred promise and that promise doesn't get resolved or rejected . Try the following:

var forEachMatch = function(matches) {var deferred = Q.defer();matches.forEach(function(match) {    var messages = Message.find({'matchid': match._id}, function(err,messages) {        if(err)            deferred.reject(err);        else            deferred.resolve(match._id);    });});return deferred.promise;

};

the caller will then become

    forEachMatch(matches).then(id=>{     console.log("done succesffuly found");   }).catch(err=>{         console.log("not found error",err);   }).done(()=>{         console.log("done")   });

In your case match better to use Q.all, which accepts array of promises or values:

var forEachMatch = function(matches) {  var promises = matches.map(match => {    return Message      .find({'matchid': match._id})      .then(messages => [match, messages]);  });  return Q.all(promises);}forEachMatch(matches)  .then(results => {    console.log("DONE", results);    res.status(200).json({      bob,      matches: matches,  });});

https://github.com/kriskowal/q/wiki/API-Reference#promiseall

You never called the promise.reject or promise.reject methods. Also, a promise is made for asynchronous operations, which forEach isn't.

Here is a dirty fix:

 var forEachMatch = function(matches) {  var deferred = Q.defer();  // make the foreach asynchronous  setTimeout(function() {    matches.forEach(function(match) {      // do stuff    });    // notify end    deferred.resolve();  }, 0);  return deferred.promise;};// use .thenforEachMatch(matches).then(function() {  console.log("DONE");});