/**
  * Provides a dataset of links for sorting products.
  */
 function SortLinks()
 {
     if (count(ProductGroup::get_sort_options()) <= 0) {
         return null;
     }
     $sort = isset($_GET['sortby']) ? Convert::raw2sql($_GET['sortby']) : "Title";
     $dos = new DataObjectSet();
     foreach (ProductGroup::get_sort_options() as $field => $name) {
         $current = $field == $sort ? 'current' : false;
         $dos->push(new ArrayData(array('Name' => $name, 'Link' => $this->Link() . "?sortby={$field}", 'Current' => $current)));
     }
     return $dos;
 }