如何在下拉菜单中输入广播信号

Question

在angularjs和materialjs中。

选择在下拉列表中，收音机不在下拉列表中

Codepen

如何在下拉菜单中进行单选输入？我必须完全自己编写代码吗？还是有一些隐藏的属性？

    <div class="radioButtondemoBasicUsage" ng-app="MyApp">
  <form ng-controller="AppCtrl" ng-cloak="">
    <p>Selected Value: <span class="radioValue">{{ data.group1 }}</span> </p>

    <md-radio-group ng-model="data.group1">

      <md-radio-button value="Apple" class="md-primary">Apple</md-radio-button>
      <md-radio-button value="Banana"> Banana </md-radio-button>
      <md-radio-button value="Mango">Mango</md-radio-button>
    </md-radio-group>

    <hr>
      <div>
        <span>What is your favorite weapon?</span>
        <md-select ng-model="weapon" placeholder="Weapon" class="md-no-underline">
          <md-option value="axe">Axe</md-option>
          <md-option value="sword">Sword</md-option>
          <md-option value="wand">Wand</md-option>
          <md-option value="pen">Pen?</md-option>
        </md-select>
      </div>


  </form>
</div>