AngularJS：ng-options刷新时ng-model不更新

Question

I'm new to AngularJS, so I apologize if this question is naive. 我是AngularJS的新手，所以我很抱歉这个问题很幼稚。

We have cascading selects that populate as you select values. 当您选择值时，我们会填充级联选择。 When the value of Select A changes, the values in Select B also change since they filter based on the value in Select A. 当选择A的值更改时，选择B中的值也会更改，因为它们基于选择A中的值进行过滤。

So here is the scenario: 所以这是场景：

Choose option from Select A 从选择A中选择选项
Choose option from Select B 从选择B中选择选项
Change selection for Select A 更改选择A的选择
Observe that options in Select B update accordingly. 请注意，选择B中的选项会相应更新。
Observe that bound model for Select B does not update accordingly. 请注意，Select B的绑定模型不会相应更新。

This seems so basic that we are really scratching our heads. 这似乎很基础，我们真的很难抓。 What is the point of two-way data binding if this scenario isn't covered? 如果不解决此问题，双向数据绑定有什么意义？

Here is my view: 这是我的看法：

    <body ng-controller="MainCtrl">
   Make:
    <select ng-model="makeng" ng-options="option.value as option.display for option in makes">
        <option ng-disabled="true"  ng-selected="true" value="">Select a make</option>
    </select>
  <br /> 
  {{makeng}}

  <br /> <br /> 

  Model:
    <select ng-model="modelng" ng-options="option.display for option in models | filter:{make:makeng}">
        <option ng-disabled="true"  ng-selected="true" value="">Select a model</option>
    </select>
    {{modelng}}
  </body>

Here's a Plunkr, demonstrating: http://plnkr.co/edit/9XrKgW?p=preview 这是一个Plunkr，演示： http ://plnkr.co/edit/9XrKgW?p=preview

PS The above example is purely fictional and forked from another plunkr. PS上面的例子纯粹是虚构的，是从另一个笨蛋派生出来的。 Just the easiest way to demonstrate what we are seeing. 展示我们所见所见的最简单方法。

Answer 1

This is how it is supposed to work. 这是应该如何工作的。 The select control changes the model in response to a user's selection, but if you change the set of allowed values from underneath it (ie by filtering out) it keeps the model intact. select控件会根据用户的选择更改模型，但是如果您从其下方更改允许值集（即通过过滤），则它将保持模型完整。

The way to make this work is by invalidating the model in response to a change in Select A : 进行此工作的方法是通过响应Select A的更改使模型无效：

Make:
<select ng-model="makeng" 
      ng-options="option.value as option.display for option in makes"
      ng-change="modelng = undefined">
   <option value="">Select a make</option>
</select>
<br /> 

Model:
<select ng-model="modelng" 
        ng-options="option.display for option in models | filter:{make:makeng}">
   <option value="">Select a model</option>
</select>

AngularJS：ng-options刷新时ng-model不更新

问题描述

1 个解决方案

解决方案1
3 已采纳 2015-02-18 21:48:44

AngularJS：ng-options刷新时ng-model不更新

问题描述

1 个解决方案

解决方案1 3 已采纳 2015-02-18 21:48:44

解决方案1
3 已采纳 2015-02-18 21:48:44