javascript - AngularJS : promises, can you pass a promise back after using .then()? -

i'm still new angular , promises hope have correct idea here.

i have data layer service uses restangular data, returns promise, this...

datastore.getusers = function (params) {     return users.getlist(params); }; 

then, controller has called function receives promise back, this...

$datastore.getusers(params).then(function (response) {     $scope.users = response; }, function(response) {     $log.error("get users returned error: ", response); }); 

this working well, i'd use promise inside of datastore before passing back. i'd use .then() method check if failed , logging, then, sucess function , failure function i'd return original promise controller.

my controller able use .then() method is, in fact, don't want controller code change @ all, datastore code.

here's semi-pseudo code show i'd datastore function do...

datastore.getusers = function (params) {      users.getlist(params).then(function (response) {         $log("server responded")         return original promise;     }, function(response) {         $log.error("server did not respond");         return original promise;     });  }; 

you not far off @ in pseudo code. promises chain:

datastore.getusers = function (params) {     return users.getlist(params).then(function (response) {         $log("server responded")         return response;     }, function(failure) {         $log.error("server did not respond");         // change throw if want angular lever logs         return $q.reject(failure);      });  }; 

the controller gets resolved/rejected same value. log requires tapping promise must add .then handler deal it. other promise libraries have convinicene methods $q minimalistic in regard.

alternatively, can use nicer catch syntax, propagate errors logs:

datastore.getusers = function (params) {     return users.getlist(params).then(function (response) {         $log("server responded")         return response;     }).catch(function(failure) {         $log.error("server did not respond");         throw failure;     });  };