title: Load relations only when a field in parent table is true
body: <p>I have a parent table named <code>Post</code> which has a boolean column named <code>is_anonymous</code>. The <code>Post</code> table has a relation to <code>Users</code> table. I want to load this relation only when <code>is_anonymous</code> set to <code>false</code>. Is there a way I can achieve this?</p>
  
  <p>The below relation gives users for all the posts.</p>
  
  <pre><code>$institute = Institute::where('inst_id', '=', $institute_id)-&gt;with(
          ['posts' =&gt; function ($posts) {
              $posts-&gt;with(['user', 'tags']);
          }]
      )-&gt;orderBy('created_at', 'DESC')-&gt;skip($skip)-&gt;take(10)-&gt;get();
  </code></pre>