How to modify request body before reaching controller in spring boot

Question

I have a spring boot application. I change the request body of every post request. Is it possible to modify the request body before the request reaches the controller. Pleas

Answer 1

One way to this is by reflection. ProceedingJoinPoint contains the args object passed to method

@Aspect
@Component
public class AopInterceptor {

    @Around(value = "@annotation(xyz.rpolnx.spring.web.poc.annotation.AopIntercepExample)")
    public Object handler(final ProceedingJoinPoint joinPoint) throws Throwable {
        HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();

        Object[] args = joinPoint.getArgs();

        Class someClass = args[0].getClass();

        Field field = someClass.getDeclaredField("custom");
        field.setAccessible(true);
        field.set(args[0], "custom");
        field.setAccessible(false);

        return joinPoint.proceed();
    }
}

@RestController
public class SimpleController {

    @PostMapping("/aop")
    @AopIntercepExample
    public Person handleAopIntercept(@RequestBody Person nodes) {
        return nodes;
    }
}

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface AopIntercepExample {
}

public class Person {
    private String name;
    private String id;
    private String custom;
}