Ui-Router $state.go inside $on('$stateChangeStart') is cauzing an infinite loop

Question

I'm trying to introduce login into the way the user navigates accross the application.

I pretend to redirect the user to the page were he was before he navigate to the login page if that page meets specific requirements

Preventing the event from the $stateChangeStart stop's the state change like expected but when i run the $state.go('into_somewhere') i enter an infinit loop

My angular version is 1.3.1 and the ui-router is the latest

.factory('RouteHistory', function ($rootScope,$log, $state, Auth, $urlRouter, $timeout) {

    // after the user enter a page
    var currentState = '';

    // when the user is trying to access a page that he has not permissions
    // or that requires the user to be logged in
    var pendingState = '';

    var isMenuTogglerVisible = false;
    var skipFromStateVal = true;

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

      event.preventDefault();



      if (toState.name == 'login' && fromState.name != 'login'){
        $log.log('Ui-router: changing to login');
        // $urlRouter.sync();
        $state.go('login')
        //pendingState = fromState;
        //$log.log('Peding state updated to:' + pendingState.name );
        //$urlRouter.sync();
      }

      if (fromState.name == 'login' && Auth.isLoggedIn()) {
        $log.log('Ui-router: going from login');
        //$state.go(fromState.name);
        $timeout(function(){
          // $state.go('home', null, {/*reload: true, location: 'replace'*/});
          $state.go('browse-machine');
          //$urlRouter.sync();
        },2000)
      }



      $log.log({
        'toState': toState,
        'toParams': toParams,
        'fromState': fromState,
        'fromParams': fromParams
      })

    })


    return {

    };
  });

Answer 1

In general I would say, let's redirect ($state.go()) only if needed. In other cases, get out from the event listener:

if (toState.name === 'login' ){
  // doe she/he try to go to login? - let him/her go
  return;
}

if(Auth.isLoggedIn()){
   // is logged in? - can go anyhwere
   return;
}

// else
$state.go('login')

This is simplified logic, but shows, that we should change to execution only if needed. There are some other examles with more detailed implementation and plunkers:

• Confusing $locationChangeSuccess and $stateChangeStart
• Angular UI Router: nested states for home to differentiate logged in and logged out
• other example of log in
• angular ui-router login authentication

As provided in the comment, there was plunker, which I changed like this here

...
// three new lines
if (toState.name === 'specialRoute'){
  return;
}

if (fromState.name=='route1'){
  event.preventDefault();
  $state.go('specialRoute')
}

And this is not looping anymore. Please, check it here

Answer 2

You should use the notify option :

$state.go('your.state',{ your params },{notify: false});

This will prevent stateChangeStart to fire again.

Answer 3

This answer helped me:

$urlRouterProvider.otherwise( function($injector, $location) {
            var $state = $injector.get("$state");
            $state.go("app.home");
        });

Original: Why does AngularJS with ui-router keep firing the $stateChangeStart event?

Answer 4

I simply used $location.path('every/where') instead of $state.go('every/where')

:) .

Answer 5

The infinite loop is partly caused by

if (toState.name == 'login' ...) { $state.go('login'); ...

..which says if you're going to the login state, then go to the login state.

...And calling event.preventDefault() as the first line in the event handler doesn't help. When you use go() to go to the login screen (or anywhere else), that state change is also prevented by event.preventDefault(). It should only be used within an if.

Your entire $stateChangeStart handler should instead be...

if (!Auth.isLoggedIn() && toState.name != 'login') {
    event.preventDefault();
    Auth.desiredState = toState.name;
    $state.go('login');
}

...which reads naturally. "If you're not logged in and you're not already going to the login screen, then stop what you're doing, I'll remember where you wanted to go, and you now go to the login screen."

Later your Auth object will issue a $state.go(Auth.desiredState) when it's satisfied with the user.

Answer 6

It works for me, Below code helps to get rid of infinite loop

  let firstPass = true;
  $scope.$on('$stateChangeStart', function(event, toState, toParams) {
    if ($scope.addForm.$dirty && firstPass) {
      event.preventDefault();
      ConfirmationDialog.openNavigateAwayConfirmationModal().then(function () {
        firstPass = false;
        return $state.go(toState, toParams);
      });
      firstPass = true;
    }
  });