Spring RequestContextHolder and WebTestClient

Question

I'm using Spring RequestContextHolder in the controller and it works fine. But in the unit test I get java.lang.IllegalStateException using WebTestClient . Here is an example:

package demo.reactive.controller;

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.context.request.RequestContextHolder;
import reactor.core.publisher.Mono;

@RestController
public class FooController {

  @GetMapping("/foo")
  public ResponseEntity<Mono<String>> foo() {

    String sessionId = RequestContextHolder.currentRequestAttributes().getSessionId();

    return ResponseEntity.ok(Mono.just(sessionId));
  }
}

package demo.reactive;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.reactive.WebFluxTest;
import org.springframework.test.web.reactive.server.WebTestClient;
import demo.reactive.controller.FooController;

@WebFluxTest(FooController.class)
class DemoReactiveApplicationTests {

  @Autowired private WebTestClient client;

  @Test
  void contextLoads() {
    client.get().uri("/foo").exchange().expectStatus().isOk();
  }
}

java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request. at org.springframework.web.context.request.RequestContextHolder.currentRequestAttributes(RequestContextHolder.java:131) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE] Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: Error has been observed at the following site(s): |_ checkpoint ⇢ HTTP GET "/foo" [ExceptionHandlingWebHandler] Stack trace: at org.springframework.web.context.request.RequestContextHolder.currentRequestAttributes(RequestContextHolder.java:131) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE] at demo.reactive.controller.FooController.foo(FooController.java:15) ~[classes/:na] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na] at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na] at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na] at org.springframework.web.reactive.result.method.InvocableHandlerMethod.lambda$invoke$0(InvocableHandlerMethod.java:147) ~[spring-webflux-5.2.5.RELEASE.jar:5.2.5.RELEASE] at reactor.core.publisher.FluxFlatMap.trySubscribeScalarMap(FluxFlatMap.java:151) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoFlatMap.subscribeOrReturn(MonoFlatMap .java:53) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:48) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:153) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55) ~[reactor-core -3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:150) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.innerNext(FluxConcatMap.java:274) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.FluxConcatMap$ConcatMapInner.onNext(FluxConcatMap.java:851) ~[reactor-core-3.3.4.RELEASE.Z6899 5FCBF432492D15484D04A9D2AC40Z:3.3.4.RELEASE] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onNext(MonoPeekTerminal.java:173) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2274) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.request(MonoPeekTerminal.java:132) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:162) ~ [reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2082) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:1956) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:90) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onSubscribe(MonoPeekTerminal.java:145) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:5 4) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.Mono.subscribe(Mono.java:4210) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:441) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe(FluxConcatMap.java:211) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:161) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86) ~[reactor-core-3.3.4.RELEASE.Z68995FCB F432492D15484D04A9D2AC40Z:3.3.4.RELEASE] at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.Mono.subscribe(Mono.java:4210) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:172) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at org.spring framework.test.web.reactive.server.HttpHandlerConnector.lambda$doConnect$1(HttpHandlerConnector.java:97) ~[spring-test-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.mock.http.client.reactive.MockClientHttpRequest.lambda$null$2(MockClientHttpRequest.java:121) ~[spring-test-5.2.5.RELEASE.jar:5.2.5.RELEASE] at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:44) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.Mono.subscribe(Mono.java:4210) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.FluxConcatIterable$ConcatIterableSubscriber.onComplete(FluxConcatIterable.Z93F725A07423FE1C889F448B33D21F 46Z:146) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.FluxConcatIterable.subscribe(FluxConcatIterable.java:60) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoFromFluxOperator.subscribe(MonoFromFluxOperator.java:72) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at org.springframework.test.web.reactive.server.HttpHandlerConnector.doConnect(HttpHandlerConnector.java:108) ~[spring-test-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.test.web.reactive.server.HttpHandlerConnector.lambda$connect$0(HttpHandlerConnector.java:79) ~[spring-test-5.2.5.RELEASE.jar:5.2.5.RELEASE] at reactor.core.publ isher.MonoDefer.subscribe(MonoDefer.java:44) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.Mono.subscribe(Mono.java:4210) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.publisher.MonoSubscribeOn$SubscribeOnSubscriber.run(MonoSubscribeOn.java:124) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.scheduler.WorkerTask.call(WorkerTask.java:84) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at reactor.core.scheduler.WorkerTask.call(WorkerTask.java:37) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE] at java.base/java.util.concurrent.FutureTask.run(FutureTask.Z93F725A07423FE 1C889F448B33D21F46Z:264) ~[na:na] at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304) ~[na:na] at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na] at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na] at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]

How can I get the unit test to work. Or it's not even suppose to use RequestContextHolder with WebFlux?

Answer 1

Spring RequestContextHolder cannot be used with Spring Webflux. RequestContextHolder primary works using java.lang.ThreadLocal . This clearly doesn't fit with Reactor architecture.

Having said that, We can implement an alternative using reactor's Mono#subscriberContext() operator. The best way to create a reusable solution is to implement spring WebFilter to get hold of request attributes and set it in the reactor context.

public class WebRequestAttributesContextFilter implements WebFilter {

  public static final String WEB_REQUEST_ATTRIBUTES = "WebRequestAttributes";

  @Override
  public Mono<Void> filter(ServerWebExchange serverWebExchange, WebFilterChain webFilterChain) {
    return webFilterChain.filter(serverWebExchange)
        .subscriberContext(context -> context.put(WEB_REQUEST_ATTRIBUTES, serverWebExchange.getAttributes()));
  }
}

The attributes (sessionId in your case) can then be read from the reactor context anywhere in the request processing pipeline as follows:

@GetMapping("/foo")
public Mono<String> helloWorld() {
  return Mono.subscriberContext().map(context -> (String) context.<Map<String, Object>>get(
          WebRequestAttributesContextFilter.WEB_REQUEST_ATTRIBUTES
      ).get("session"));
}

Answer 2

You should rather use subscriberContext from Mono/Flux API.

Take a look on docs: https://projectreactor.io/docs/core/release/api/reactor/core/publisher/Mono.html#subscriberContext--