angular ui router - AngularJS, $digest error trying to redirect application on pages requiring login

Question

I'm trying to redirect an AngularJS app in the case that the requested state requires login. This is the method I've placed within the 'run' method on my angular app:

$rootScope.$on('$stateChangeStart', function(event, toState, toParams, fromState, fromParams) {

  if(toState.data.requiresLogin && !User.isLoggedIn)
  {
    event.preventDefault();
    $state.go('login');
  }
});

Seems straightforward, but I'm getting this digest error. It appears to be triggered by the event.preventDefault() statement. I can't remove that of course...

Error: [$rootScope:infdig] 10 $digest() iterations reached. Aborting!
Watchers fired in the last 5 iterations: [["fn: $locationWatch; newVal: 7; oldVal: 6"],["fn:     $locationWatch; newVal: 8; oldVal: 7"],["fn: $locationWatch; newVal: 9; oldVal: 8"],["fn: $locationWatch; newVal: 10; oldVal: 9"],["fn: $locationWatch; newVal: 11; oldVal: 10"]]
...

Any advice on how to refactor this to clear this error, or what the error even means?

Answer 1

There is a working example, how to redirect to login. Firstly there are 4 states defined - 2 of them require authentication, third is public (for anybody) and there is also login state:

$stateProvider
    // available for anybody
    .state('public',{
        url : '/public',
        template : '<div>public</div>',
    })
    // just for authenticated
    .state('some',{
        url : '/some',
        template : '<div>some</div>',
        data : {requiresLogin : true },
    })
    // just for authenticated
    .state('other',{
        url : '/other',
        template : '<div>other</div>',
        data : {requiresLogin : true },
    })
    // the log-on screen
    .state('login',{
        url : '/login',
        templateUrl : 'tpl.login.html',
        controller : 'UserCtrl',
    })

and that would be the $stateChangeStart def, which always redirects to login - if required ... only login itslef and public are available always/to anybody

.run(['$rootScope', '$state', 'User', function($rootScope, $state, User)
{

  $rootScope.$on('$stateChangeStart'
    , function(event, toState, toParams, fromState, fromParams) {

    var isAuthenticationRequired =  toState.data 
          && toState.data.requiresLogin 
          && !User.isLoggedIn
      ;

    if(isAuthenticationRequired)
    {
      event.preventDefault();
      $state.go('login');
    }
  });
}])

Check that all in action here