title: How to implement ngModel on custom elements?
body: <p>Given a simple <code>input</code> element I can do this:</p>
  <pre class="lang-html prettyprint-override"><code>&lt;input [(ngModel)]=&quot;name&quot; /&gt; {{ name }}
  </code></pre>
  <p>This doesn't work for my custom elements:</p>
  <pre class="lang-html prettyprint-override"><code>&lt;my-selfmade-combobox [(ngModel)]=&quot;name&quot; values=&quot;getValues()&quot; required&gt;&lt;/my-selfmade-combobox&gt;
  </code></pre>
  <p>How can I implement it?</p>