title: Angular orderBy multiple fields with priority given to one field
body: <p>Following on from a previous question on this topic (<a href="https://stackoverflow.com/questions/17037524/orderby-multiple-fields-in-angular">orderBy multiple fields in Angular</a>), I'm wondering if it is possible to achieve <a href="http://jsfiddle.net/abyrne85/apfw1Lm5/3/" rel="nofollow noreferrer">this</a>.   Essentially, I want to orderBy multiple fields, but give priority to one of the fields if their value isn't null.</p>
  
  <p>I'm using orderBy like so: </p>
  
  <pre><code>orderBy:['-sub','group']
  </code></pre>
  
  <p>From what I understand, the first item in the list of fields is given priority, but they are appearing at the bottom of the list.  </p>