Using promises with angular

gistfile1.js

angular.module('example')
.factory('Users', function($q, $http) {
  var users = null;
  
  return {
    get: function() {
      deferred = $q.defer();
      
      if (users) {
          deferred.resolve(users);
      }
      else {
          $http.get('/api/users/').then(
              function(res) {
                  users = res.data;
                  deferred.resolve(users)
              },
              function(err) {
                  deferred.resolve(err);
              }
          )
      }
      return deferred.promise;
    }  
  };
}).
controller('exampleCtrl', function($scope, Users) {
    Users.get().then(function(users) {
       $scope.users = users;
    });
});