angularjs - How to get the specific data in a response inside controller? -

i have code of login. getting data response hosting okay , ng-repeat in view once it's validate shows data. want make validation it, want specific data ex:username in data compare user input. when try specific entity username or password in controller, undefined variable shows alert figure selected. how able that? can me solve this.

$scope.login = function (user) {      userfactory.login($scope.users).then(function (response) {          console.log("student profile" + angular.tojson(response));          $scope.user = response.data;          alert($scope.user.username);          alert($scope.user.password);      }, function (err) {          var alertpopup = $ionicpopup.alert({              title: 'login failed!',              template: 'please check credentials!'          });      });  };

<button class="button button-block button-balanced" ng-click="login(user)">login</button>  <div class="list card">      <div class="container">          <div ng-repeat="item in user">               id: {{item.user_id}}                firstname: {{item.firstname}}                lastname: {{item.lastname}}                token: {{item.access_token}}</div>      </div>  </div>