Accessing ModelView attributes in Spring ResponseBodyAdvice - spring

Question

For all my RestControllers handlers, which all return a subtype of MyResponseType, I would like to write a Spring ResponseBodyAdvice which manipulates the response based on some #ModelAttribute. However, I don't know how to access the ModelView at this place.
#ControllerAdvice
public class MyGoldenAdvice implements ResponseBodyAdvice<MyResponseType> {
#Override
public boolean supports(final MethodParameter returnType, final Class<? extends HttpMessageConverter<?>> converterType) {
return true;
}
#Override
public RepresentationModel<?> beforeBodyWrite(
final MyResponseType body,
final MethodParameter returnType,
final MediaType selectedContentType,
final Class<? extends HttpMessageConverter<?>> selectedConverterType,
final ServerHttpRequest request,
final ServerHttpResponse response) {
// here I would like to access the ModelView
return body;
}
}
Unfortunately, since I have to implement the interface ResponseBodyAdvice, I cannot have #ModelAttribute arguments.
Of course, I could also use an interceptor. However, there the response is already written, thus I could only manipulate the JSON of my MyResponseType instance.
Any idea?

Answer 1

Although it is not a solution to the concrete question (Access zu #ModelAttributes) and violates the idea behind #ControllerAdvice, you can use #RequestAttributes for the same purpose. For this, the advice needs a dependency to current HttpServletRequest to store and get the attribute (the ServerHttpRequest argument of beforeBodyWrite does not provide request attributes).
public class MyGoldenAdvice implements ResponseBodyAdvice<MyResponseType> {
public final static String ATTRIBUTE_NAME="MyGoldenAdviceAttribute";
private final HttpServletRequest currentRequest;
// spring injects a proxy to the current request
#Autowired
public MyGoldenAdvice(HttpServletRequest currentRequest) {
this.currentRequest = currentRequest;
}
// in order that the advice method is triggered, we have to annotate it
// with #ModelAttribute, although we store the attribute in the request
#ModelAttribute
public MyModelAttributeType createModelAttribute() {
MyModelAttributeType attribute = MyModelAttributeType.build();
currentRequest.setAttribute(ATTRIBUTE_NAME, attribute);
return attribute;
}
#Override
public boolean supports(final MethodParameter returnType, final Class<? extends HttpMessageConverter<?>> converterType) {
return true;
}
#Override
public RepresentationModel<?> beforeBodyWrite(
final MyResponseType body,
final MethodParameter returnType,
final MediaType selectedContentType,
final Class<? extends HttpMessageConverter<?>> selectedConverterType,
final ServerHttpRequest request,
final ServerHttpResponse response) {
// get the request attribute
MyModelAttributeType attribute = (MyModelAttributeType) currentRequest.getAttribute(ATTRIBUTE_NAME);
// do something with the body
return body;
}
}
In some REST controller, you can use the request attribute as follows
#GetMapping
public handleGetRequest(#RequestAttribute(name=MyGoldenAdvice.ATTRIBUTE_NAME)
MyModelAttributeType attribute) {
// pass attribute around in services and so on...
}