$on 加载一次新的引用 AngularFire 0.5.0 [英] $on loaded fires once for new references AngularFire 0.5.0

问题描述

假设使用 pushState 来导航路线:

Let's say were using pushState to navigate routes:

$locationProvider.html5Mode(true);

并且有两个路由，有两个不同的控制器:

And there are two routes with two different controllers:

$stateProvider.state('one', {
  url:'/one',
  templateUrl:'one.html',
  controller: 'oneCtrl'
});

$stateProvider.state('two', {
  url:'/two',
  templateUrl:'two.html',
  controller: 'twoCtrl'
});

oneCtrl 创建对与 twoCtrl 相同资源的新引用:

oneCtrl creates a new reference to the same resource as twoCtrl:

.controller('oneCtrl', ["$scope", "$firebase", function($scope, $firebase) {

  var oneRef = new Firebase("https://example.firebaseio.com/stuff");
  $scope.stuff = $firebase(oneRef);
  $scope.stuff.$on("loaded", function(value) {
    console.log(value);
  });
}])

.controller('twoCtrl', ["$scope", "$firebase", function($scope, $firebase) {

  var twoRef = new Firebase("https://example.firebaseio.com/stuff");
  $scope.stuff = $firebase(twoRef);
  $scope.stuff.$on("loaded", function(value) {
    console.log(value);
  });
}])

• 如果我们导航到 /one，$on("loaded") 事件会按预期触发 - oneRef 独有.立>
• 如果我们然后从 /one 导航到 /two，$on("loaded") 事件不会触发.
• If we navigate to /one the $on("loaded") event fires as expected - unique to the oneRef.
• If we then navigate from /one to /two the $on("loaded") event does not fire.

如果一个新的 ref 被实例化 - twoRef - 为什么回调不会第二次触发?

If a new ref was instantiated - twoRef - why doesn't the callback fire a second time?

推荐答案

这是因为本地缓存的数据会在 Firebase 中同步触发 value 事件.

This is due to the fact that locally cached data fires value events synchronously in Firebase.

在第一次加载时，angularFire 的 _getInitialValue<异步联系服务器/a> 方法.但是，在第二次加载时，由于该值已经是本地的，广播事件 同步发生，因此在您的 $on('loaded'...) 处理程序被附加之前.

On the first load, the server is contacted asynchronously by angularFire's _getInitialValue method. However, on the second load, since the value is already local, the broadcast event happens synchronously, and therefore before your $on('loaded'...) handler gets attached.

我想到了一些想法:如果控制器使用相同的 $firebase 数据，那么在最常见的用例中可能只有一个.应将其移至服务并相应地共享.

A couple thoughts come to mind: If the controllers are utilizing the same $firebase data, there should probably--in most common use cases--only be one. It should be moved to a service and shared accordingly.

另一种解决方法是将加载状态存储在服务或 $rootScope 中.

Another workaround would be to store the loaded state in a service or in the $rootScope.

最终，它应该在angularFire中更正，以便加载的事件触发，即使值"已同步加载.

Ultimately, it should be corrected in angularFire so that the loaded event triggers even if the 'value' is already loaded synchronously.

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