$inv_maincategory = new Inv_maincategory($_POST['key']);
         $inv_maincategory->populate();
         $inv_maincategory->store();
         $inv_subcategories = Inv_subcategory::findByMainCategoryCode($_POST['key']);
         foreach ($inv_subcategories as $inv_subcategory) {
             $inv_subcategory->setMainCategoryCode($_POST['category_code']);
             $inv_subcategory->store();
         }
     } catch (fExpectedException $e) {
         echo $e->printMessage();
     }
 } else {
     if ($_POST['type'] == "delete") {
         try {
             $inv_maincategory = new Inv_maincategory($_POST['key']);
             $inv_maincategory->delete();
             $inv_subcategories = Inv_subcategory::findByMainCategoryCode($_POST['key']);
             foreach ($inv_subcategories as $inv_subcategory) {
                 $inv_subcategory->delete();
             }
         } catch (fExpectedException $e) {
             echo $e->printMessage();
         }
     } else {
         if ($_POST['type'] == "add") {
             try {
                 $inv_maincategory = new Inv_maincategory();
                 $inv_maincategory->populate();
                 $inv_maincategory->store();
             } catch (fExpectedException $e) {
                 echo $e->printMessage();