spring boot override default REST exception handler

Question

I am not able to override default spring boot error response in REST api. I have following code

@ControllerAdvice
@Controller
class ExceptionHandlerCtrl {

    @ResponseStatus(value=HttpStatus.UNPROCESSABLE_ENTITY, reason="Invalid data")
    @ExceptionHandler(BusinessValidationException.class)
    @ResponseBody
    public ResponseEntity<BusinessValidationErrorVO> handleBusinessValidationException(BusinessValidationException exception){
        BusinessValidationErrorVO vo = new BusinessValidationErrorVO()
        vo.errors = exception.validationException
        vo.msg = exception.message
        def result =  new ResponseEntity<>(vo, HttpStatus.UNPROCESSABLE_ENTITY);
        result

    }

Then in my REST api I am throwing this BusinessValidationException. This handler is called (I can see it in debugger) however I still got default spring boot REST error message. Is there a way to override and use default only as fallback? Spring Boot version 1.3.2 with groovy. Best Regards

Answer 1

Remove @ResponseStatus from your method. It creates an undesirable side effect and you don't need it, since you are setting HttpStatus.UNPROCESSABLE_ENTITY in your ResponseEntity.

From the JavaDoc on ResponseStatus:

Warning: when using this annotation on an exception class, or when setting the reason attribute of this annotation, the HttpServletResponse.sendError method will be used.

With HttpServletResponse.sendError, the response is considered complete and should not be written to any further. Furthermore, the Servlet container will typically write an HTML error page therefore making the use of a reason unsuitable for REST APIs. For such cases it is preferable to use a ResponseEntity as a return type and avoid the use of @ResponseStatus altogether.