AngularJS $ watch根范围变量进行更改 [英] AngularJS $watch root scope variable for changes

问题描述

我有以下$ rootScope变量，该变量用于保存当前登录的用户特权级别，然后从其他控制器访问此变量.有没有一种方法可以监视rootScope变量的更改，以便通过对根范围变量的任何更改来更新控制器特定的变量?以下是到目前为止我正在使用的代码，有人可以告诉我我在做什么错以及如何解决吗?谢谢

I have the following $rootScope variable which I use to save the current logged in user privilege level, then I access this variable from other controllers. Is there a way I can watch the rootScope variable for changes in order to update controllers specific variables with any changes to the root scope variable? Below is the code I am using so far, can someone please tell me what I am doing wrong and how to fix it? Thanks

在.run下的app.js中:

In app.js under .run:

 $rootScope.uPLevel = 0;

.controller

.controller

   $scope.$watch($rootScope.uPLevel, function() {
            $scope.userPLevel = $rootScope.uPLevel;
   }, true);

推荐答案

$watch的第一个参数应该是字符串或函数(

The first parameter to $watch should either be a string or a function (docs). Right now you're passing it the value of $rootScope.uPLevel on controller initialization.

$scope.$watch(function() {
  return $rootScope.uPLevel;
}, function() {
  $scope.userPLevel = $rootScope.uPLevel;
}, true);

两个旁注:

• 最好将此值存储在服务中，而不要存储在$rootScope中.
• 如果uPLevel仅是一个整数(如您的示例所示)，则无需将true作为第三个参数传递-仅用于数组和对象.如果您确实想观看收藏，则建议使用$watchCollection代替.

• It may be prudent to store this value in a service instead of $rootScope.
• If uPLevel is only an integer (as your example suggests) then you don't need to pass true as the third parameter - that's only for arrays and objects. If you do want to watch a collection, then I suggest using $watchCollection instead.

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