How can I use a ngModel on an ion-radio element?
<p>I'm trying to implement a ngModel on a ion-radio element but somehow it doesn't work. This is my code:</p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>import {
  Page
} from 'ionic-angular';

@Page({
  templateUrl: 'build/pages/settings/settings.html'
})

export class Settings {
  constructor() {
    this.unit = 2;
  }
}</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;ion-list radio-group&gt;
  &lt;ion-list-header&gt;
    Unit
  &lt;/ion-list-header&gt;

  &lt;ion-item&gt;
    &lt;ion-label&gt;Metric (kg)&lt;/ion-label&gt;
    &lt;ion-radio value="1" [(ngModel)]="unit"&gt;&lt;/ion-radio&gt;
  &lt;/ion-item&gt;

  &lt;ion-item&gt;
    &lt;ion-label&gt;Imperial (lbs)&lt;/ion-label&gt;
    &lt;ion-radio value="2" [(ngModel)]="unit"&gt;&lt;/ion-radio&gt;
  &lt;/ion-item&gt;
&lt;/ion-list&gt;</code></pre>
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</div>
</p>

<p>I've tried implementing it on a ion-input and ion-select and that just works fine. I also tried adding <code>directives: [FORM_DIRECTIVES]</code> to my @Page and added the corresponding import but that doesn't fix the problem.</p>

<p>Any ideas? </p>