Vue: Binding radio to boolean : <p>I'm having trouble binding radiobuttons to boolean values in model.</p>

<p>In this example: <a href="https://jsfiddle.net/krillko/npv1snzv/2/" rel="noreferrer">https://jsfiddle.net/krillko/npv1snzv/2/</a></p>

<p>On load, the radio radio button is not checked, and when I try to change them, the 'primary' value in model is becomes empty.</p>

<p>I've tried:</p>

<pre><code>:checked="variation.primary == true"
</code></pre>

<p>but with no effect. </p>
