Payload Route Handler

[Camila]

Hello, Thank you for this tutorial! I have a question, can you help me? Thinking in Spark 2.6.0, I`m using the RouteGroup for map my routes: public class Service { public static void main(String[] args) { ... path("/areas", AreaRouteGroup.paths); } } And the "AreaRouteGroup" is look like this: public class AreaRouteGroup { private static ResponseTransformer transformer = new JsonResponseTransformer(); private static String acceptType = "application/json"; public static RouteGroup paths = () -> { get("", AreaController.listAll, transformer); get("/:id", AreaController.findById, transformer); post("", acceptType, AreaController.create, transformer); put("/:id", acceptType, AreaController.change); }; } An exemplo of the controller method is the create: public class AreaController { ... public static Route create = (Request request, Response response) -> { AreaPayload payload = JsonMapper.jsonToData(request.body(), AreaPayload.class); Map<String, String> errors = payload.validate(); if (!errors.isEmpty()) { return HttpResponse.badRequest(response, errors); } Area area = dao.create(payload.getName()); return HttpResponse.created(response, area); }; ... } I`m trying to remove the boilerplate from lines 1-6 in the above controller method using the an interface PayloadHandler: public interface PayloadHandler<V extends Validable> extends Route { @SuppressWarnings({ "unchecked", "unused" }) public default Object handle(Request request, Response response) throws Exception { try { // TODO: get the valueClass of generic type; Class<?> valueClass = null; V value = null; if (valueClass == EmptyPayload.class) { value = (V) JsonMapper.jsonToData(request.body(), valueClass); } Map<String, String> errors = value.validate(); if (!errors.isEmpty()) { return HttpResponse.badRequest(response, errors); } else { return handle(value, request, response); } } catch (JsonMappingException e) { System.out.println(e.getMessage()); String error = "Invalid JSON"; return HttpResponse.internalError(response, error); } finally { request.session().invalidate(); } } Object handle(V value, Request request, Response response); } But this solution is not working because I`m do not know how to get the valueClass of generic type in the first line after the try. I`m imagining a solution similar the Exception handler where is possible to say the class type of Exception: https://github.com/perwendel/spark/blob/master/src/main/java/spark/ExceptionHandler.java exception(Exception.class, (exception, request, response) -> { response.status(500); response.body(exception.getMessage()); }); Is it possible? Thank you again.