指令链接函数中的 scope.$watch 未被调用 [英] scope.$watch in directive link function not getting called

问题描述

我有这家工厂，

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

    return {
      loginRequired: false
    };
  }]);

我有这个控制器，

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

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

}]);

我在指令中有这个链接函数，

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;
    });
  }

当 authentication.loginRequired = true; 在控制器中完成时，指令中的 scope.$watch 不会被调用.

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

知道为什么吗?

推荐答案

Scope.$watch 接受作为第一个参数表达式或函数.您作为第一个参数传递的是存储在 authetication.loginRequired 中的 值.

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

以下将起作用(假设您已正确注入 authetication 工厂):

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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