How to get the #RequestBody in an #ExceptionHandler (Spring REST) - spring

Question

I am using Spring Boot 1.4.1 which includes spring-web-4.3.3. I have a class annotated with #ControllerAdvice and methods annotated with #ExceptionHandler to handle exceptions thrown by the service code. When handling these exceptions, I would like to log the #RequestBody that was part of the request for PUT and POST operations so I can see the request body that caused the problem which in my case is crucial for diagnosis.
Per Spring Docs the method signature for #ExceptionHandler methods can include various things including the HttpServletRequest. The request body can normally be obtained from here via getInputStream() or getReader(), but if my controller methods parse the request body like "#RequestBody Foo fooBody" as all of mine do, the HttpServletRequest's input stream or reader is already closed by the time my exception handler method is called. Essentially the request body has already been read by Spring, similar to the issue described here. It is a common problem working with servlets that the request body can only be read once.
Unfortunately #RequestBody is not one of the options available for the exception handler method, if it were then I could use that.
I can add an InputStream to the exception handler method, but that ends up being the same thing as the HttpServletRequest's InputStream and so has the same issue.
I also tried getting the current request with ((ServletRequestAttributes) RequestContextHolder.currentRequestAttributes()).getRequest() which is another trick for getting the current request, but this ends up being the same HttpServletRequest that Spring passes into the exception handler method and so has the same problem.
I have read about a few solutions like this and this that involve inserting a custom request wrapper in the filter chain that will read the contents of the request and cache them so they can be read more than once. I don't like this solution because I don't want to interrupt the entire filter/request/response chain (and potentially introduce performance or stability problems) just to implement logging, and if I have any large requests such as uploaded documents (which I do), I don't want to cache that in memory. Besides, Spring probably has the #RequestBody cached somewhere already if I could only find it.
Incidentally many solutions recommend using the ContentCachingRequestWrapper Spring class but in my experience this does not work. Aside from not being documented, looking at its source code it looks like it only caches the parameters, but not the request body. Trying to get the request body from this class always results in an empty string.
So I am looking for any other options that I may have missed. thanks for reading.

Answer 1

Accepted answer creates a new POJO to pass things around, but the same behaviour can be achieved without creating additional objects by reusing the http request.
Example code for Controller mapping:
public ResponseEntity savePerson(#RequestBody Person person, WebRequest webRequest) {
webRequest.setAttribute("person", person, RequestAttributes.SCOPE_REQUEST);
And later in the ExceptionHandler class / method you can use:
#ExceptionHandler(Exception.class)
public ResponseEntity exceptionHandling(WebRequest request,Exception thrown) {
Person person = (Person) request.getAttribute("person", RequestAttributes.SCOPE_REQUEST);

Answer 2

You can reference the request body object to a request-scoped bean. And then inject that request-scoped bean in your exception handler to retrieve the request body (or other request-context beans that you wish to reference).
// #Component
// #Scope("request")
#ManagedBean
#RequestScope
public class RequestContext {
// fields, getters, and setters for request-scoped beans
}
#RestController
#RequestMapping("/api/v1/persons")
public class PersonController {
#Inject
private RequestContext requestContext;
#Inject
private PersonService personService;
#PostMapping
public Person savePerson(#RequestBody Person person) throws PersonServiceException {
requestContext.setRequestBody(person);
return personService.save(person);
}
}
#ControllerAdvice
public class ExceptionMapper {
#Inject
private RequestContext requestContext;
#ExceptionHandler(PersonServiceException.class)
protected ResponseEntity<?> onPersonServiceException(PersonServiceException exception) {
Object requestBody = requestContext.getRequestBody();
// ...
return responseEntity;
}
}

Answer 3

You should be able to get the content of the request body by using the RequestBodyAdvice interface. If you implement this on a class annotated with #ControllerAdvice it should be picked up automatically.
To get other request information like the HTTP method and query params I'm using an interceptor. I'm capturing all this request info for error reporting in a ThreadLocal variable which I clear on the afterCompletion hook in that same interceptor.
The class below implements this and can be used in your ExceptionHandler to get all request information:
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.MethodParameter;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
import org.springframework.web.servlet.mvc.method.annotation.RequestBodyAdvice;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Type;
import java.util.HashMap;
import java.util.Map;
#ControllerAdvice
public class RequestInfo extends HandlerInterceptorAdapter implements RequestBodyAdvice {
private static final Logger logger = LoggerFactory.getLogger(RequestInfo.class);
private static final ThreadLocal<RequestInfo> requestInfoThreadLocal = new ThreadLocal<>();
private String method;
private String body;
private String queryString;
private String ip;
private String user;
private String referrer;
private String url;
public static RequestInfo get() {
RequestInfo requestInfo = requestInfoThreadLocal.get();
if (requestInfo == null) {
requestInfo = new RequestInfo();
requestInfoThreadLocal.set(requestInfo);
}
return requestInfo;
}
public Map<String,String> asMap() {
Map<String,String> map = new HashMap<>();
map.put("method", this.method);
map.put("url", this.url);
map.put("queryParams", this.queryString);
map.put("body", this.body);
map.put("ip", this.ip);
map.put("referrer", this.referrer);
map.put("user", this.user);
return map;
}
private void setInfoFromRequest(HttpServletRequest request) {
this.method = request.getMethod();
this.queryString = request.getQueryString();
this.ip = request.getRemoteAddr();
this.referrer = request.getRemoteHost();
this.url = request.getRequestURI();
if (request.getUserPrincipal() != null) {
this.user = request.getUserPrincipal().getName();
}
}
public void setBody(String body) {
this.body = body;
}
private static void setInfoFrom(HttpServletRequest request) {
RequestInfo requestInfo = requestInfoThreadLocal.get();
if (requestInfo == null) {
requestInfo = new RequestInfo();
}
requestInfo.setInfoFromRequest(request);
requestInfoThreadLocal.set(requestInfo);
}
private static void clear() {
requestInfoThreadLocal.remove();
}
private static void setBodyInThreadLocal(String body) {
RequestInfo requestInfo = get();
requestInfo.setBody(body);
setRequestInfo(requestInfo);
}
private static void setRequestInfo(RequestInfo requestInfo) {
requestInfoThreadLocal.set(requestInfo);
}
// Implementation of HandlerInterceptorAdapter to capture the request info (except body) and be able to add it to the report in case of an error
#Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
RequestInfo.setInfoFrom(request);
return true;
}
#Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception exception) {
RequestInfo.clear();
}
// Implementation of RequestBodyAdvice to capture the request body and be able to add it to the report in case of an error
#Override
public boolean supports(MethodParameter methodParameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
return true;
}
#Override
public HttpInputMessage beforeBodyRead(HttpInputMessage inputMessage, MethodParameter parameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
return inputMessage;
}
#Override
public Object afterBodyRead(Object body, HttpInputMessage inputMessage, MethodParameter parameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
RequestInfo.setBodyInThreadLocal(body.toString());
return body;
}
#Override
public Object handleEmptyBody(Object body, HttpInputMessage inputMessage, MethodParameter parameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
return body;
}
}

Answer 4

Just an enhancement to quintencls answer
I got request body and can use it anywhere inside exception handler class.
#ControllerAdvice
public class CustomErrorHandler extends ResponseEntityExceptionHandler implements RequestBodyAdvice {
...
private Object reqBody;
...
#ExceptionHandler(NoSuchElementException.class)
public ResponseEntity<Object> handleNoSuchElementException(final NoSuchElementException ex,
final WebRequest request) {
System.out.println("===================================" + reqBody);
return handleNotFoundException(ex, request);
}
...
#Override
public boolean supports(MethodParameter methodParameter, Type targetType,
Class<? extends HttpMessageConverter<?>> converterType) {
return true;
}
#Override
public HttpInputMessage beforeBodyRead(HttpInputMessage inputMessage, MethodParameter parameter, Type targetType,
Class<? extends HttpMessageConverter<?>> converterType) throws IOException {
return inputMessage;
}
#Override
public Object afterBodyRead(Object body, HttpInputMessage inputMessage, MethodParameter parameter, Type targetType,
Class<? extends HttpMessageConverter<?>> converterType) {
// capture request body here to use in our controller advice class
this.reqBody = body;
return body;
}
#Override
public Object handleEmptyBody(Object body, HttpInputMessage inputMessage, MethodParameter parameter,
Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
return body;
}
}

Answer 5

Here is a solution in Kotlin syntax that I used for some fields validation control.
I needed to enhance the default handleMethodArgumentNotValid(...) method from the #RestControllerAdvice, to systematically log a field that was embedded in that same request body object.
override fun handleMethodArgumentNotValid(e: MethodArgumentNotValidException, headers: HttpHeaders, status: HttpStatus, request: WebRequest): ResponseEntity<Any> {
val error = e.bindingResult.fieldErrors.first()
val requestBody = try {
val field = error.javaClass.getDeclaredField("violation").apply { trySetAccessible() }
((field[error] as ConstraintViolationImpl<Any>).rootBean as MyRequestBodyObject)
} catch (ex : Exception) {
//do some failsafe here
}
}

Answer 6

See here: https://stackoverflow.com/a/61813076/1036433 - for a clean way to have access to the HttpServerRequest.