angularjs - Angular JS service dependency injection error -

i new angular have been trying asynchronous validation username availability , getting "cannot read property 'username' of undefined" here service code

webappservices.factory('services', ['$resource', function ($resource){     return{         users: $resource('http://localhost:8080/api/users',{},{             get:{method:'get',isarray:true},             add:{method:'post',isarray:false},             update:{method:'post',isarray:false}         }),         username:$resource('http://localhost:8080/api/users/check/:username',{},{             check:{method:'get',isarray:false}         })     };}]); 

here directive code passes username validation

webappvalidation.directive('checkusername', ['services', function ($q, services) {     return {         require: "ngmodel",         link: function (scope, elm, attrs, ctrl) {             ctrl.$asyncvalidators.checkusername = function(modelvalue, viewvalue){                //check username                 return ctrl.$isempty(modelvalue) || services.username.check({username:modelvalue}).                         then(function resolved(){                             //username exists, means validation fails                             return $q.reject('exists');                         }, function rejected(){                             //username not exists, therefore validation passes                             return true;                         });             };         }     }; }]); 

and getting in console

typeerror: cannot read property 'username' of undefined @ link.ctrl.$asyncvalidators.checkusername (validations.js:56) @ angular.js:24723 @ foreach (angular.js:350) @ processasyncvalidators (angular.js:24722) @ ngmodelcontroller.$$runvalidators (angular.js:24681) @ ngmodelcontroller.$$parseandvalidate (angular.js:24819) @ ngmodelcontroller.$commitviewvalue (angular.js:24787) @ angular.js:24920 @ scope.$get.scope.$eval (angular.js:15719) @ scope.$get.scope.$apply (angular.js:15818) 

you not injecting $q service.

webappvalidation.directive('checkusername', ['$q','services', ... 

i write this

webappservices.factory('usersservice', ['$q','$http',    var endpoint = 'http://localhost:8080/api/user';    function ($q, $http){     var _getusers = function(){        var deffered = $q.defer();         $http.get(endpoint)             .then(               function(data){ deffered.resolve(data);}),               function(data){ deffered.reject(data);})             ).catch(function(error){  $q.reject(error);});         deffered.promise;   }  //...  //the other methods  //...     return{        getusers: _getusers        //...     } ;}]); 

although $http returns promise, better return $q thenable object follow specifications of promises, users of services didnt confused seeing then ... undefined