javascript - 用户界面路由器 : Difference between onEnter and onStart?

Question

我正在切换到新版本的 ui-router (1.0.0-alpha.5) 并试图找出在哪里使用 onEnter 钩子(Hook)以及在哪里 < strong>onStart:

$transitions.onStart()

和

$transitions.onEnter()

在它只是事件之前 $stateChangeStart

Answer 1

这是如何the doc描述了转换生命周期钩子(Hook)的执行顺序:

onBefore
onStart/onInvalid
onEnter (for individual states)
onSuccess
onError

...但它似乎有点过时了(我稍后再谈)。不过，它清楚地表明 onEnter Hook 是关于进入状态，而 onStart Hook 是关于开始状态之间的转换 em>.

实际上，the hook doc pages 中对该关键区别进行了很好的描述:

onStart hooks are invoked asynchronously, in priority order, when the Transition starts running. At this point, the Transition has not exited nor entered any states yet.

onEnter hooks are invoked asynchronously, in priority order, when the Transition is entering a state. States are entered after the onRetain hooks.

onStart Hook 似乎是验证转换的好地方 - 例如，检查用户是否经过身份验证。这是该文档中给出的代码示例:

$transitions.onStart( { to: 'auth.*' }, function(MyAuthService, $state) {
  // If the user is not authenticated
  if (!MyAuthService.isAuthenticated()) {

    // Then return a promise for a successful login.
    // The transition will wait for this promise to settle
    return MyAuthService.authenticate().catch(function() {

      // Redirect to a state that we know doesn't require auth.
      return $state.target("guest");
    });
  }
});

---

从最后一页来看，顺序实际上是:

onBefore - Transition is about to start; one can register other hooks here "on-the-fly"
onStart  - Transition starts running
onExit   - Transition is exiting a state
onRetain - Transition retains a state
onEnter  - Transition is entering a state 
onFinish - Transition is about to be completed, all states are entered and exited

onSuccess/onError - Transition is completed (either successfully or not)

注意:除了最后两个钩子(Hook)之外的所有钩子(Hook)都可以修改转换 - 更改目标状态等。onSuccess 和 onError 在事后触发:转换结束。