title: RESTful expand by default
body: <p>How can I return model relations without adding expand parameter in url? I tried add some code in model</p>
  
  <pre><code>public function fields()
  {
      $fields = parent::fields();
  
      $fields['profile'] = $this-&gt;profile;
  
      return $fields;
  }
  </code></pre>
  
  <p>But i am getting the error:</p>
  
  <pre><code>call_user_func() expects parameter 1 to be a valid callback, no array or string given
  </code></pre>
  
  <p>This method works:</p>
  
  <pre><code>$_GET['expand'] = 'profile';
  </code></pre>
  
  <p>but it's bad solution.</p>