Spring exception handler , can't access request attributes

manpreet Best Answer 2 years ago

I have this controller using spring boot 2.1

@Controller
@AllArgsConstructor
@ControllerAdvice
public class AdminPoolsController {

@PostMapping("admin/pools/edit")
    public String update(@Valid final PoolDto pool,
                         @RequestParam(name = "image-upload", required = false) final MultipartFile file,
                         final BindingResult bindingResult,
                         final RedirectAttributes redirectAttrs) throws IOException {
        //some logic
    }


    @ExceptionHandler(MaxUploadSizeExceededException.class)
    public String fileSizeLimitExc(
            final HttpServletRequest request,
            final RedirectAttributes redirectAttributes,
            final MaxUploadSizeExceededException exc
    ) {
        final Object id = request.getAttribute("id");
        redirectAttributes.addFlashAttribute(
                "errors",
                ImmutableMap.of(
                        "logo",
                        String.format(
                                "File exceeded max size of %d bytes",
                                exc.getMaxUploadSize()
                        )
                )
        );
        return "redirect:/admin/pools/edit" + (id == null ? "" : "?id=" + id.toString());
    }

}

As you see I have PoolDto in POST method , this DTO has id , binding happen through html form

<input type="hidden" name="id" id="id" th:value="${pool.id}">

In html form I can provide file using input type file , but this file is limited in size therefore I catch MaxUploadSizeExceededException My problem is , HttpServletRequest inside error handling method doesn't have any request attributes , in my case I want to get id from original request , but it is always null. How can I catch original request attributes using ExceptionHandler ?

manpreet 2 years ago

If a request hits the maximum upload size, the request body is never fully processed. Instead, it is cancelled when the limit is reached. Therefore, data transmitted in the request body is not available. That is not related to Spring Boot. It's a more fundamental restriction.

To pass some ID, you basically have three options:

1. Put the ID in the URL, e.g. admin/pool/edit/123 or admin/pool/edit?id=123

2. Store the ID in a cookie.

3. Store the ID in the session. The session ID is retained via a cookie.