AOP @Around: return BAD_REQUEST response

Question

In a Spring rest application, every single URL must start with an application id (appId). This appId must be validated in every single rest service. Instead of duplicating code, I tried to create an @Aspect with an @Around advice. This is correctly executed before any rest method.

However, if the application id is unknown, I do not want neither to create a stack trace or neither to return a 200 (response OK). Instead I do want to return a BAD_REQUEST response code.

If I throw an exception in my advice, I get a stack trace and no HTTP response. If I on the other hand return anything else (but do not call the pjp.proceed), I get a return code of 200.

Could anyone please assist me on returning a response code 400 to the requestor?

Below my code so far:

@Component
@Aspect
public class RequestMappingInterceptor {

    @Autowired
    ListOfValuesLookupUtil listOfValuesLookupUtil;

    @Around("@annotation(requestMapping)")
    public Object around(ProceedingJoinPoint pjp, RequestMapping requestMapping) throws Throwable {
        Object[] arguments = pjp.getArgs();
        if(arguments.length == 0 || !listOfValuesLookupUtil.isValidApplication(arguments[0].toString())) {
            // toto : return bad request here ...
            throw new BadRequestException("Application id unknown!");
        } else {
            return pjp.proceed();
        }
    }
}

Answer 1

You need to access the HttpServletResponse and use that to send the error code. You can do this via the RequestContextHolder

@Around("@annotation(requestMapping)")
public Object around(ProceedingJoinPoint pjp, RequestMapping requestMapping) throws Throwable {
    Object[] arguments = pjp.getArgs();
    if(arguments.length == 0 || !listOfValuesLookupUtil.isValidApplication(arguments[0].toString())) {
        HttpServletResponse response = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getResponse());
        response.sendError(HttpStatus.PRECONDITION_FAILED.value(), "Application Id Unknown!");
        return null;
    } else {
        return pjp.proceed();
    }
}