title: how to get laravel-admin grid value
body: <p>i want to use laravel grid add a link with product_id (not PK) to open new window with iframe-tabs
  for search</p>
  
  <p>i have tried assign variable from grid ,but it always say </p>
  
  <p>Object of class Encore\Admin\Grid\Column could not be converted to string</p>
  
  <pre class="lang-php prettyprint-override"><code>protected function grid()  
  {
  
    $userModel = config('admin.database.pm_model');
  
    $grid = new Grid(new $userModel());
    $grid-&gt;id('ID')-&gt;sortable();
    $grid-&gt;sn(trans('admin.product_id'))-&gt;sortable();
    $product_id = $grid-&gt;sn(trans('admin.product_id'))-&gt;value();
  
    $grid-&gt;com_num(trans('admin.com_num'))-&gt;sortable()-&gt;link( 
        '/admin/com/search/'.$product_id,'','' );
  </code></pre>
  
  <p>1.how can i get $product_id from $grid->sn</p>
  
  <p>2.how can i set route to other page like /admin/com/search/123 for search not edit</p>