Turns out this can be achieved using the provided decorators: ServerWebExchangeDecorator, ServerHttpRequestDecorator and ServerHttpResponseDecorator, respectively.
Here's a sample request decorator that accumulates the DataBuffer contents as its read by the request's default subscriber:
@Slf4j
public class CachingServerHttpRequestDecorator extends ServerHttpRequestDecorator {
@Getter
private final OffsetDateTime timestamp = OffsetDateTime.now();
private final StringBuilder cachedBody = new StringBuilder();
CachingServerHttpRequestDecorator(ServerHttpRequest delegate) {
super(delegate);
}
@Override
public Flux<DataBuffer> getBody() {
return super.getBody().doOnNext(this::cache);
}
@SneakyThrows
private void cache(DataBuffer buffer) {
cachedBody.append(UTF_8.decode(buffer.asByteBuffer())
.toString());
}
public String getCachedBody() {
return cachedBody.toString();
}
Just make sure that, when you decorate the ServerWebExchange passed by the WebFilter, you also override getRequest() to return the request decorator as well:
public final class PartnerServerWebExchangeDecorator extends ServerWebExchangeDecorator {
private final ServerHttpRequestDecorator requestDecorator;
private final ServerHttpResponseDecorator responseDecorator;
public PartnerServerWebExchangeDecorator(ServerWebExchange delegate) {
super(delegate);
this.requestDecorator = new PartnerServerHttpRequestDecorator(delegate.getRequest());
this.responseDecorator = new PartnerServerHttpResponseDecorator(delegate.getResponse());
}
@Override
public ServerHttpRequest getRequest() {
return requestDecorator;
}
@Override
public ServerHttpResponse getResponse() {
return responseDecorator;
}
}
On the filter:
@Component
public class TracingFilter implements WebFilter {
@Override
public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
return chain.filter(new PartnerServerWebExchangeDecorator(exchange));
}
}
Which can be used as such (beware the statically imported functions):
@Bean
public HttpHandler myRoute(MyHandler handler) {
final RouterFunction<ServerResponse> routerFunction =
route(POST("/myResource"), handler::persistNotification);
return webHandler(toWebHandler(routerFunction))
.filter(new TracingFilter())
.build();
}
