title: get nested relations data $lookup
body: <p>i have collection page and page has many widgets:</p>
  
  <p>page collection :</p>
  
  <pre><code>_id
  name
  slug,
  widget_codes
  </code></pre>
  
  <p>widget collection :</p>
  
  <pre><code>_id
  name
  code
  type
  product_ids
  category_ids
  </code></pre>
  
  <p>product collection:</p>
  
  <pre><code>_id
  name
  type
  </code></pre>
  
  <p>category collection:</p>
  
  <pre><code>_id
  name
  type
  </code></pre>
  
  <p>for retrieve data i use like this:</p>
  
  <pre><code>public function getData($page) {
      return $page-&gt;raw(function ($collection) use ($page) {
          return $collection-&gt;aggregate([
              [
                  '$lookup' =&gt; [
                      'from'         =&gt; 'widgets',
                      'localField'   =&gt; 'widget_codes',
                      'foreignField' =&gt; 'code',
                      'as'           =&gt; 'widgets',
                  ]
              ],
              [
                  '$match' =&gt; ['slug' =&gt; $page-&gt;slug]
              ]
          ]);
      });
  }
  </code></pre>
  
  <p>it works perfect and get widget data now i want to get product and category data with widget using that widget has product_ids and category_ids what query can i use.</p>