angularjs + ui-router:当用户未登录每个状态更改时,重定向到登录页面

我正在使用angularjs和ui-router构建一个简单的博客应用程序,我想监听每个状态更改并检查用户是否已登录.如果他不是,我想将他重定向到登录页面.

这个场景非常简单,我试图在没有运气的情况下实现这个解决方案.

这是相关代码:

app.config(function($stateProvider, $urlRouterProvider){
    $stateProvider.state('app', {
        url: '',
        abstract: true
    });
    $urlRouterProvider.otherwise('blogs');
});

app.run(function($rootScope, $state, $location, UserService){
    $rootScope.$on('$stateChangeStart', function(event, toState, toParams, fromState, fromParams){
    console.log("state change: from state: " + fromState.name + " to state: " + toState.name);
        let loggedIn = UserService.isLoggedIn();
        if (toState.name !== 'app.login' && !loggedIn){
            event.preventDefault();
            $state.go('app.login');
    });
});

其中'app.login'被定义为登录状态,'blogs'是我的主要供稿的网址,我希望该应用程序将在启动时进入.

在查看chrome控制台时,当没有用户登录时,我看到:

[HMR] Waiting for update signal from WDS...
state change: from state:  to state: app.blogs
state change: from state:  to state: app.login
state change: from state:  to state: app.blogs
state change: from state:  to state: app.login
state change: from state:  to state: app.blogs
state change: from state:  to state: app.login
state change: from state:  to state: app.blogs
state change: from state:  to state: app.login
state change: from state:  to state: app.blogs
state change: from state:  to state: app.login
Error: [$rootScope:infdig] 10 $digest() iterations reached. Aborting!
Watchers fired in the last 5 iterations: []
http://errors.angularjs.org/1.4.5/$rootScope/infdig?p0=10&p1=%5B%5D
    at REGEX_STRING_REGEXP (angular.js:68)
    at Scope.$get.Scope.$digest (angular.js:15753)
    at Scope.$get.Scope.$apply (angular.js:15986)
    at bootstrapApply (angular.js:1658)
    at Object.invoke (angular.js:4473)
    at doBootstrap (angular.js:1656)
    at Object.bootstrap (angular.js:1676)
    at Object. (bootstrap.js:4)
    at __webpack_require__ (bootstrap 7b71f5eb02d2540fe63f:520)
    at fn (bootstrap 7b71f5eb02d2540fe63f:75)
Uncaught Error: [$rootScope:infdig] 10 $digest() iterations reached. Aborting!
Watchers fired in the last 5 iterations: []
http://errors.angularjs.org/1.4.5/$rootScope/infdig?p0=10&p1=%5B%5D
XHR finished loading: GET "http://localhost:8080/login/login.html".

它出现了好几次.此外 - 网址在/ login和/ blogs之间跳转.

我究竟做错了什么？

(编辑:我在console.log中添加了一些调试)

出于某种原因,此代码有效:

app.run(function($rootScope, $state, $location, UserService){
    $rootScope.$on('$stateChangeStart', function(event, toState, toParams, fromState, fromParams){
        let loggedIn = UserService.isLoggedIn();
        if  (toState.name !== 'app.login' && !loggedIn){
            $location.url('/login');
        }
    });
});

我改变了从$ state.go到 $ location.url重定向到登录页面的方式.

每次我使用$state.go它都会引发另一个$stateChangeStart事件,这显然是错误的.这样event.preventDefault()就没有必要了.