title: REST API with complex queries
body: <p>I don't fully understand how to make complex queries with REST API on the backend, and a backbone web app on the frontend. Say I have a <code>user</code> table that has a relation with a <code>user_group</code> table:</p>
  
  <pre><code>user.group_ref =&gt; user_group.id
  </code></pre>
  
  <p>If I do a <code>GET</code> on <code>/api/v1/user/1/?format=json</code> it will do something like <code>SELECT * FROM users WHERE id = 1</code>. Right, ok, now... how about if I wanted to <code>JOIN</code> with my <code>user_group</code> where <code>user.group_ref = user_group.id</code> to instantly have access to the data on <code>user_group</code>. I don't want to do an extra query to go and fetch that data. </p>
  
  <p>Maybe I got the whole idea wrong ... Is there a simpler way?</p>