范围。$手表指令链接功能没有得到所谓的 [英] scope.$watch in directive link function not getting called

问题描述

我有这样的工厂，

.factory('authentication', [function() {

    return {
      loginRequired: false
    };
  }]);

我有这样的控制器，

I have this controller,

.controller('TopNavCtrl', ['$scope', 'authentication', function($scope, authentication) {

  $scope.login = function() {
    authentication.loginRequired = true;
  };

}]);

和我有一个指令，这个链接功能，

and I have this link function in a directive,

link: function(scope, element, attrs) {

    scope.show = false;

    scope.$watch(authentication.loginRequired, function(value) {
      scope.show = value;
    });
  }

在 authentication.loginRequired = TRUE; 在控制器完成后， $范围看中的指令不叫。

When authentication.loginRequired = true; is done in the controller, the scope.$watch in the directive isn't called.

任何想法，为什么？

推荐答案

范围。$看接受作为第一个参数前pression或功能。你所传递的第一个参数是一个值保存在 authetication.loginRequired 。

Scope.$watch accepts as first parameter expression or function. What you are passing as first parameter is a value stored in authetication.loginRequired.

下面的工作（假设你已经正确地注入 authetication 厂）：

Following will work (assuming you have correctly injected authetication factory):

link: function(scope, element, attrs) {

    scope.show = false;

    scope.$watch(function(){return authentication.loginRequired;}, function(value) {
      scope.show = value;
    });
  }

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