title: Bulk updates of related models
body: <p>Update single...</p>
  <p><code>$modelA-&gt;update(['status_id' =&gt; 1])</code></p>
  <p>Update multiple...</p>
  <p><code>ModelA::whereIn('id', $data['ids'])-&gt;update(['status_id' =&gt; 1])</code></p>
  <p>SO</p>
  <p>Updating a model <strong>related</strong> to a single row can work as follows...</p>
  <p><code>$modelA-&gt;relatedModel()-&gt;update(['status_id' =&gt; 1])</code></p>
  <p>($modelA instance is supplied via route model binding, and the relatedModel() method/relationship is defined in the &quot;ModelA&quot; model)</p>
  <p>BUT</p>
  <p>When attempting the following,</p>
  <p><code>ModelA::whereIn('id', $data['ids'])-&gt;relatedModel()-&gt;update(['status_id' =&gt; 1])</code></p>
  <p>I get an error</p>
  <p>Call to undefined method Illuminate\Database\Eloquent\Builder::relatedModel()</p>
  <p>It seems that I am not really understanding what is being returned by</p>
  <p><code>ModelA::whereIn('id', $data['ids'])</code></p>
  <p>So what I'm looking for is a method of updating the related models of multiple rows (obviously without a loop of any kind).</p>