Defer Angular UI Router $stateChangeStart until server authorization response receieved

Question

I have an Angular app using UI Router where I'm trying to validate a user's token, if one exists, when the app runs. I am also checking that the user has permission to access certains routes. The problem is that $stateChangeStart is running before I receive the response back from the authorization endpoint. Here's some code (coffeescript with js below) - this is all within my run block.

app.run(($rootScope, $state, $stateParams, $log, Auth) ->

  currentState = 'home'

  $rootScope.$state = $state

  # read a cookie if cookie exists
  if Auth.setAuthenticationToken()
    # hit api endpoint to validate token
    Auth.validateToken (user) ->
      # route to current state
      # this returns after $stateChangeStart runs below
      $state.go(currentState)

  $rootScope.$on '$stateChangeStart', (event, toState, toParams, fromState, fromParams) ->

    currentState = toState.name

    Auth.setAuthenticationToken()

    $rootScope.error = null

    # compare users access permissions with incoming route's access level
    if (!Auth.authorize toState.data.access, Auth.user)
      event.preventDefault()
      $rootScope.error = "Sorry, you haven't provided the required credentials."
      $log.warn $rootScope.error
)

My question is how can I get the $stateChangeStart to run only after the response from the auth endpoint has been returned. This only needs to happen the first time. Every subsequent state change can be done without hitting the auth endpoint.

Answer 1

I'd create a function in your Auth service that returns a promise. Later, resolve (authorized) or reject (not authrized) that deferred. Then use it on the resolve property of your route definitions

$stateProvider.state('stateName',{
    ...
    ...
    resolve: {
         isAuthorized: function(Auth){
             return Auth.checkAuthorization();
         }
    }
})

To support subsequent checks you could maintain a promise within the service This might look like:

myApp.service('Auth',function($http,$q){
    var authStatusDeferred = $q.defer();
    this.checkAuthorization = function(){
        return authStatusDeferred.promise;
    };

    this.validateToken = function(user){
        var isValid = false;
        //..do validation stuff
        if(isValid) authStatusDeferred.resolve();
        //Otherwise state change will not happen..            
    };



});

oh, sorry about no coffee