Spring REST Multipart error handling

Question

I have this REST Controller that should also handle exceptions.

The @ExceptionHandler(MultipartException.class) annotation is not working as explained.

So I am implementing HandlerExceptionResolver which is basically working but is not as handy for REST and JSON responses as @ExceptionHandler would be.

I would like to return my custom class ValidationReport in resolveException similar to the @ExceptionHandler handleBadRequest. I was not able to create a ModelAndView with a ValidationReport json response. Any Idea how I can combine both styles?

@RestController
class ValidationController implements HandlerExceptionResolver{
    static Logger LOG = LoggerFactory.getLogger(ValidationController.class);


@RequestMapping(value="/validate", method=[POST])
public ValidationReport validate(MultipartFile file) {
    LOG.info("received file ${file?.name}")
    ValidationReport report = new ValidationReport();
    return report
}


@ResponseStatus(BAD_REQUEST)
@ExceptionHandler(MultipartException.class)
@ResponseBody ValidationReport handleBadRequest(HttpServletRequest req, Exception ex) {
    return new ValidationReport(USER_ERROR, "you should not upload files bigger then xx MB")
}

@Override
ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
    if (ex instanceof MultipartException){
        response.sendError(BAD_REQUEST.value(),ex.message)
    }
    return null
}
}

I

Answer 1

This is not a solution I am not really happy with but one that works. I implement the HandlerExceptionResolver Interface to catch all exceptions.

In the implemented Method I handle only the exception I am interested in. Then I send the caller a error code and tell him what he did wrong.

@Override
ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {

    if (ex instanceof MultipartException){
        response.sendError(413,"Content is to big. Maximal allowed request size is: ${Application.MAX_REQUEST_SIZE}")
    }
}