Question

我很困惑关于角度的2路数据绑定。看看代码吧！ var bah可以访问父对象$scope.something但是当我单击按钮时，控制器中的值更改为false但不是指令。怎么了？那是一个错误吗？

如何解决这个问题？感谢帮助我，希望你能写一个例子或参考链接

HTML

<div ng-controller="myController">
  show me something {{ something }} <br>
  <button ng-click="toggleSomething"><button>

  <!-- this is a canvas -->
  <my-directive></my-directive>
</div>

JS

angular.module('fooBar',[]).controller('myController', ['$scope', function($scope) {
   // this is the something
   $scope.something = true;

   $scope.toggleSomething = function(){
     if($scope.something) { 
       $scope.something = false 
     } else { 
       $scope.something = true 
     }
   }

}]).directive('myDirective', function(){
  return {
    template: '<canvas width="500px" height="500px"></canvas>',
    link: function(scope, el, attr) {
      //how to access that 'something'
      var bah = scope.$parent.something;
    }
  };
});

UPDATE 非常感谢大家。特别是对于你@immirza

很抱歉，我不能一一回复你。它只需添加$parent

//how to access that 'something'
var bah = scope.$parent.something

Answer 1

您可以直接访问$scope.something中的myDirective，而无需使用$parent，因为该指令有shared scope

并且对于你的问题，如果你试图检测指令内的something更改你不能只放一个console.log($scope.something)并检查因为它只执行了一次并且在点击之后它不再打印，这并不意味着something内的directive没有变化。

并且你在ng-click中犯了一个错误，例如ng-click="toggleSomething"它应该是ng-click="toggleSomething()"，因为你调用的函数不仅仅是一个变量。

这是一个DEMO

我已将<h1> ... {{ something }}</h1>放在指令模板中，以显示某些内容在指令中也按预期工作。

通过这个优秀的directive series

Answer 2

我已经为您的代码添加了一个plunker并添加了对该指令的双向绑定。你可以在plnkr

看到它

angular.module('fooBar',[]).controller('myctr', ['$scope', function($scope) {
   // this is the something
   $scope.something = true;

   $scope.toggleSomething = function(){
     if($scope.something) { 
       $scope.something = false 
     } else { 
       $scope.something = true 
     }
   }

}]).directive('myDirective', function(){
  return {
    //changed canvas to span so for simplixity.
    template: '<span width="500px" height="500px">{{blah}} --- {{ dsomething }}</span>',
    scope: { dsomething: "=" },
    link: function(scope, el, attr) {

      //watching $parent.variable is not recommonded as it makes your
      //directive less reusable and forces who ever wants to use your
      //directive to create the variable.  dsomething will just update
      //nicely w/o any code in this link function. the code below is just to demonstrate
      //how to get it done by using $watch with $parent scope.

      //how to access that 'something'
      if(!scope.dsomething){
        scope.dsomething = "something";
      }

      //because blah is a local variable and not a two-way binding variable
      //we need to use $watch to update the value.
      //you can use "dsomething" instead of "$parent.something"
      //
      scope.$watch("$parent.something", function(newVal, oldVal){
         scope.blah = newVal;
      })
    }
  };
});

您可以将您的指令用作：

<div ng-controller="myctr">
  show me something {{ something }}             <br />
  <button ng-click="toggleSomething()">Update Something</button>
  <button>
    <!-- this is a canvas -->
    <my-directive dsomething="something"></my-directive>
  </button>
</div>

注意ng-click =＆＃34; toggleSomething（）＆＃34;。它是一个不通过函数的函数调用。纳克单击=＆＃34; toggleSomething＆＃34;不会工作。

Answer 3

问题是你误解了双向数据绑定是什么，基本上任何带有指令的two way bound元素都可以被控制器或指令更新，而另一个会立即看到这个变化反映在其中

当您使用$parent访问它时，您正在强行读取指令中的值，仅此而已，没有人告诉指令重新评估var bah = scope.$parent.something，因为scope.something的值已经在父控制器中更新。

2路数据绑定指令角度

3 个答案: