public function invoke($filter)
 {
     $AllCustomers = new CustomerView();
     if ($filter == "") {
         if (isset($_SESSION['role']) && $_SESSION['role'] == "Administrator") {
             $AllCustomers->showCustomers();
         } else {
             $AllCustomers->showCustomersONLY();
         }
     } else {
         if (isset($_SESSION['role']) && $_SESSION['role'] == "Administrator") {
             $AllCustomers->showCustomersfiltered($filter);
         } else {
             $AllCustomers->showCustomersfilteredONLY($filter);
         }
     }
 }