title: Conditionally set the disabled state of a bootstrap button
body: <p>I have the following button in my view:</p>
  
  <pre><code>&lt;button type="button" class="btn btn-lg btn-primary"&gt;Primary button&lt;/button&gt;
  </code></pre>
  
  <p>I want to add the <code>disabled</code> property to it if and only a certain condition is <code>true</code>. How do I this in an elegant way?</p>