父指令属性更改时子指令未更新 [英] Child directive not updated when parent directive property changes

问题描述

这是对这两个问题的跟进:

1. 在父子指令之间传递参数
2. 父指令控制器在传递给子指令时未定义

我有这部分工作；但是，当父指令的 ng-disabled 值发生变化时，子指令的值不会更新.

请参阅简单的 plunkr 示例.

HTML:

<div ng-controller="MyController">{{菜单状态}}<tmp-menu ng-disabled="menuStatus"><tmp-menu-link></tmp-menu-link><tmp-menu-link></tmp-menu-link></tmp-菜单><button ng-click="updateStatus()">更新</button>

JavaScript(AngularJS):

angular.module('myApp', []).controller('MyDirectiveController', MyDirectiveController).controller('MyController', function($scope){$scope.menuStatus = false;$scope.updateStatus = function(){$scope.menuStatus = $scope.menuStatus?false:true;}}).directive('tmpMenu', function() {返回 {限制:'AE'，替换:真，转置:真，范围:{禁用:'=?ngDisabled'},控制器:'MyDirectiveController'，模板:'<div>myDirective Disabled: {{ disabled }}<ng-transclude></ng-transclude></div>',链接:函数(范围，元素，属性){}};}).directive('tmpMenuLink', function() {返回 {限制:'AE'，替换:真，转置:真，范围:{},要求:'^^tmpMenu',模板: '<div>childDirective disabled: {{ disabled }}</div>',链接:函数(范围、元素、属性、MyDirectiveCtrl){控制台.log(MyDirectiveCtrl);scope.disabled = MyDirectiveCtrl.isDisabled();}};})函数 MyDirectiveController($scope) {this.isDisabled = function() {返回 $scope.disabled;};}

如何检测父指令的变化并将其传递给子指令而不添加角度观察器.

解决方案

解决方案 1

我在这里设置了一个有效的 plnkr:https://plnkr.co/edit/fsxMJPAc05imhBqefaRk?p=preview

这种行为的原因是 tmpMenuLink 保留了从 MyDirectiveCtrl.isDisabled() 返回的值的副本.没有设置观察者，因此解决此问题的唯一方法是手动观察任何更改，然后更新该字段.

scope.$watch(function(){返回 MyDirectiveCtrl.isDisabled();}， 功能(){scope.disabled = MyDirectiveCtrl.isDisabled();})

解决方案 2

没有观察者的替代方法是传递对象的引用而不是原始类型，例如:

$scope.menuStatus = {status: false};

新 plnkr 在这里:https://plnkr.co/edit/RGEK6TUuE7gkPDS6ygZe?p=preview

This is follow up to these 2 questions:

1. Pass argument between parent and child directives
2. Parent directive controller undefined when passing to child directive

I have this part working; however, when the value for ng-disabled for parent directive changes, the child directive values don't get updated.

Please see thin plunkr example.

HTML:

<div ng-app="myApp">
  <div ng-controller="MyController">
    {{menuStatus}}
    <tmp-menu ng-disabled="menuStatus">
      <tmp-menu-link></tmp-menu-link>
      <tmp-menu-link></tmp-menu-link>
    </tmp-menu>
    <button ng-click="updateStatus()">Update</button>
  </div>
</div>

JavaScript(AngularJS):

angular.module('myApp', [])
.controller('MyDirectiveController', MyDirectiveController)
.controller('MyController', function($scope){
  $scope.menuStatus = false;
  $scope.updateStatus = function(){
    $scope.menuStatus = $scope.menuStatus?false:true;
  }
})
.directive('tmpMenu', function() {
  return {
    restrict: 'AE',
    replace:true,
    transclude:true,
    scope:{
      disabled: '=?ngDisabled'
    },
    controller: 'MyDirectiveController',
    template: '<div>myDirective Disabled: {{ disabled }}<ng-transclude></ng-transclude></div>',
    link: function(scope, element, attrs) {


    }
  };
})
.directive('tmpMenuLink', function() {
  return {
    restrict: 'AE',
    replace:true,
    transclude:true,
    scope:{
    },
    require:'^^tmpMenu',
    template: '<div>childDirective disabled: {{ disabled }}</div>',
    link: function(scope, element, attrs, MyDirectiveCtrl) {
      console.log(MyDirectiveCtrl);

      scope.disabled = MyDirectiveCtrl.isDisabled();

    }
  };
})

function MyDirectiveController($scope) {
  this.isDisabled = function() {
    return $scope.disabled;
  };
}

How can I detect change in parent directive and pass it to child directive without adding angular watcher.

解决方案

Solution 1

i've set up a working plnkr here: https://plnkr.co/edit/fsxMJPAc05imhBqefaRk?p=preview

the reason of this behaviour is that tmpMenuLink kept a copy of the value returned from MyDirectiveCtrl.isDisabled(). no watcher is set up , so the only way to resolve this is to manually watch for any changes and then update the field.

scope.$watch(function(){
  return MyDirectiveCtrl.isDisabled();
}, function(){
   scope.disabled = MyDirectiveCtrl.isDisabled();
})

Solution 2

An alternative without watchers is to pass the reference of an object instead of a primitive type, something like:

$scope.menuStatus = {status: false};

new plnkr here: https://plnkr.co/edit/RGEK6TUuE7gkPDS6ygZe?p=preview

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