Refactor department-level permission checks and enhance handling of empty department filters across routes and related object methods.

services/nginx/app/objects/users_o.php

@@ -653,7 +653,7 @@ class users_o extends db
         self::requireSelected();
         // Get the group of the user
         $group = new groups_o();
-        $group->select($this->group_id->value());
+        $group->select((int)$this->group_id->value());
         return $group;
     }