title: Angular 2 - Assign value to checkbox using reactive form
body: <p>I'm trying to assign a value to a checkbox when checked and nothing (or <code>false</code>) when unchecked:</p>
  
  <pre><code>&lt;input type="checkbox" [value]="key" [formControlName]="variable"/&gt;
  </code></pre>
  
  <p>This doesn't work and the values are either <code>true</code> or <code>false</code>. Is it possible to assign a variable?</p>