角 - 如何看在我的控制器cookie的值，而不会引起＆QUOT;错误$消化（）迭代达到＆QUOT; [英] Angular - How can I watch a cookie value in my controller without causing "Error $digest() iterations reached"

问题描述

我有一个应用程序，用户将项目添加到他们的购物车。如果他们没有登录到该网站的项目都存储在他们的饼干。我想创建的人有多少项目在他们的车一视觉指示器（即的CookieStore），因为它们增加一个项目，一旦更新。

I have an app where users add items to their cart. If they are not logged into the site the items are stored in their cookies. I am trying to create a a visual indicator of how many items the person has in their cart (i.e. cookiestore) that updates as soon as they add an item.

要做到这一点，我有以下code：

To do this I have the following code:

控制器

   $scope.temporaryCart = $cookieStore.get('cart').length;

   $scope.$watch(function () {
      return $cookieStore.get('cart');
    }, function () {
      $scope.temporaryCart = $cookieStore.get('cart').length;
    });

在我的部分我有：

And in my partial I have:

    <div class="words">{{temporaryCart || 0}}</div>

如果我不包括 $ $范围看的车没有及时更新，但是，当我做包含它，我得到：

If I do not include the $scope.$watch the cart does not update, however, when I do include it, I get:

Uncaught Error: [$rootScope:infdig] 10 $digest() iterations reached. Aborting!
Watchers fired in the last 5 iterations: [[{"msg":"fn: function () {\n      return $cookieStore.get('cart');\n    }"...

这是得到像饼干的东西，从实时更新正确的方法？ - 或者我怎么能避免所有的迭代，仍然追踪存储在cookie或数据库的动态更新值​​

Is this the right approach to get real time updates from things like Cookies - or how can I avoid all of the iterations and still track a dynamically updating value stored in cookies or a database?

推荐答案

要简单地说，你的$观看功能每次都返回不同的对象，因此消化周期从未平息。换句话说，以下为真：

To put simply, your "$watched" function returns a different object every time, and so the digest cycle never settles. In other words, the following is true:

$cookieStore.put("foo", {v: "bar"});
var c1 = $cookieStore.get("foo");
var c2 = $cookieStore.get("foo");

console.log(c1 === c2); // false

（顺便说一句， $的CookieStore 是德precated，但同样会是真实与 $ cookies.getObject ）

(btw, $cookieStore is deprecated, but the same would be true with $cookies.getObject)

如果您的必须的使用Cookies来跟踪变量（当然，如果没有一个服务，的localStorage 和的sessionStorage ，在评论中指出，更适合于它），你可以设置一个$手表的属性之一：

If you must use cookies to track variables (certainly, if not a service, localStorage and sessionStorage, as noted in comments, are more suited for it), you could set a $watch for one of its properties:

$scope.$watch(function(){
  return $cookies.getObject("cart").length;
}, function(v){
  $scope.temporaryCart = v;
});

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