Add toBodilessEntity to ClientResponse and WebClient.ResponseSpec

See gh-23498

Author: poutsma

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/ClientResponse.java

@@ -59,6 +59,7 @@
  *     {@link #toEntity(ParameterizedTypeReference)}</li>
  * <li>{@link #toEntityList(Class)} or
  *     {@link #toEntityList(ParameterizedTypeReference)}</li>
+*  <li>{@link #toBodilessEntity()}</li>
  * <li>{@link #releaseBody()}</li>
  * </ul>
  * You can use {@code bodyToMono(Void.class)} if no response content is
@@ -184,6 +185,15 @@ public interface ClientResponse {
 	 */
 	<T> Mono<ResponseEntity<List<T>>> toEntityList(ParameterizedTypeReference<T> elementTypeRef);
 
+	/**
+	 * Return this response as a delayed {@code ResponseEntity} containing
+	 * status and headers, but no body. Calling this method will
+	 * {@linkplain #releaseBody() release} the body of the response.
+	 * @return {@code Mono} with the bodiless {@code ResponseEntity}
+	 * @since 5.2
+	 */
+	Mono<ResponseEntity<Void>> toBodilessEntity();
+
 	/**
 	 * Creates a {@link WebClientResponseException} based on the status code,
 	 * headers, and body of this response as well as the corresponding request.

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultClientResponse.java

@@ -162,6 +162,12 @@ public Mono<Void> releaseBody() {
 				.then();
 	}
 
+	@Override
+	public Mono<ResponseEntity<Void>> toBodilessEntity() {
+		return releaseBody()
+				.then(WebClientUtils.toEntity(this, Mono.empty()));
+	}
+
 	@Override
 	public <T> Mono<ResponseEntity<T>> toEntity(Class<T> bodyType) {
 		return WebClientUtils.toEntity(this, bodyToMono(bodyType));

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultWebClient.java

@@ -562,6 +562,14 @@ public <T> Mono<ResponseEntity<List<T>>> toEntityList(ParameterizedTypeReference
 							handleBodyFlux(response, response.bodyToFlux(elementTypeRef))));
 		}
 
+		@Override
+		public Mono<ResponseEntity<Void>> toBodilessEntity() {
+			return this.responseMono.flatMap(response ->
+					WebClientUtils.toEntity(response, handleBodyMono(response, Mono.<Void>empty()))
+							.doOnNext(entity -> response.releaseBody()) // body is drained in other cases
+			);
+		}
+
 
 		private static class StatusHandler {
 

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/WebClient.java

@@ -751,6 +751,18 @@ ResponseSpec onRawStatus(IntPredicate statusCodePredicate,
 		 * @since 5.2
 		 */
 		<T> Mono<ResponseEntity<List<T>>> toEntityList(ParameterizedTypeReference<T> elementTypeRef);
+
+		/**
+		 * Return the response as a delayed {@code ResponseEntity} containing status and headers,
+		 * but no body.  By default, if the response has status code 4xx or 5xx, the {@code Mono}
+		 * will contain a {@link WebClientException}. This can be overridden with
+		 * {@link #onStatus(Predicate, Function)}.
+		 * Calling this method will {@linkplain ClientResponse#releaseBody() release} the body of
+		 * the response.
+		 * @return {@code Mono} with the bodiless {@code ResponseEntity}
+		 * @since 5.2
+		 */
+		Mono<ResponseEntity<Void>> toBodilessEntity();
 	}
 
 

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/WebClientUtils.java

@@ -44,8 +44,7 @@ public static  <T> Mono<ResponseEntity<T>> toEntity(ClientResponse response, Mon
 			int status = response.rawStatusCode();
 			return bodyMono
 					.map(body -> createEntity(body, headers, status))
-					.switchIfEmpty(Mono.defer(
-							() -> Mono.just(createEntity(null, headers, status))));
+					.switchIfEmpty(Mono.fromCallable( () -> createEntity(null, headers, status)));
 		});
 	}
 
@@ -62,7 +61,7 @@ public static <T> Mono<ResponseEntity<List<T>>> toEntityList(ClientResponse resp
 		});
 	}
 
-	private static  <T> ResponseEntity<T> createEntity(@Nullable T body, HttpHeaders headers, int status) {
+	public static  <T> ResponseEntity<T> createEntity(@Nullable T body, HttpHeaders headers, int status) {
 		HttpStatus resolvedStatus = HttpStatus.resolve(status);
 		return resolvedStatus != null
 				? new ResponseEntity<>(body, headers, resolvedStatus)

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/support/ClientResponseWrapper.java

@@ -123,6 +123,11 @@ public Mono<Void> releaseBody() {
 		return this.delegate.releaseBody();
 	}
 
+	@Override
+	public Mono<ResponseEntity<Void>> toBodilessEntity() {
+		return this.delegate.toBodilessEntity();
+	}
+
 	@Override
 	public <T> Mono<ResponseEntity<T>> toEntity(Class<T> bodyType) {
 		return this.delegate.toEntity(bodyType);

spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientDataBufferAllocatingTests.java

@@ -16,6 +16,7 @@
 package org.springframework.web.reactive.function.client;
 
 import java.time.Duration;
+import java.util.Collections;
 import java.util.Map;
 import java.util.function.Function;
 
@@ -34,6 +35,7 @@
 import org.springframework.core.io.buffer.NettyDataBufferFactory;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
 import org.springframework.http.client.reactive.ReactorClientHttpConnector;
 import org.springframework.http.client.reactive.ReactorResourceFactory;
 import org.springframework.web.reactive.function.UnsupportedMediaTypeException;
@@ -185,6 +187,29 @@ public void releaseBody(String displayName, DataBufferFactory bufferFactory) {
 				.verify(Duration.ofSeconds(3));
 	}
 
+	@ParameterizedDataBufferAllocatingTest
+	public void exchangeToBodilessEntity(String displayName, DataBufferFactory bufferFactory) {
+		super.bufferFactory = bufferFactory;
+
+		this.server.enqueue(new MockResponse()
+				.setResponseCode(201)
+				.setHeader("Foo", "bar")
+				.setBody("foo bar"));
+
+		Mono<ResponseEntity<Void>> result  = this.webClient.get()
+				.exchange()
+				.flatMap(ClientResponse::toBodilessEntity);
+
+		StepVerifier.create(result)
+				.assertNext(entity -> {
+					assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.CREATED);
+					assertThat(entity.getHeaders()).containsEntry("Foo", Collections.singletonList("bar"));
+					assertThat(entity.getBody()).isNull();
+				})
+				.expectComplete()
+				.verify(Duration.ofSeconds(3));
+	}
+
 
 	private void testOnStatus(Throwable expected,
 			Function<ClientResponse, Mono<? extends Throwable>> exceptionFunction) {

spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientIntegrationTests.java

@@ -291,6 +291,62 @@ void retrieveShouldReceiveJsonAsResponseEntityString(ClientHttpConnector connect
 		});
 	}
 
+	@ParameterizedWebClientTest
+	void exchangeBodilessEntity(ClientHttpConnector connector) {
+		startServer(connector);
+
+		prepareResponse(response -> response
+				.setHeader("Content-Type", "application/json").setBody("{\"bar\":\"barbar\",\"foo\":\"foofoo\"}"));
+
+		Mono<ResponseEntity<Void>> result = this.webClient.get()
+				.uri("/json").accept(MediaType.APPLICATION_JSON)
+				.exchange()
+				.flatMap(ClientResponse::toBodilessEntity);
+
+		StepVerifier.create(result)
+				.consumeNextWith(entity -> {
+					assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.OK);
+					assertThat(entity.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_JSON);
+					assertThat(entity.getHeaders().getContentLength()).isEqualTo(31);
+					assertThat(entity.getBody()).isNull();
+				})
+				.expectComplete().verify(Duration.ofSeconds(3));
+
+		expectRequestCount(1);
+		expectRequest(request -> {
+			assertThat(request.getPath()).isEqualTo("/json");
+			assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo("application/json");
+		});
+	}
+
+	@ParameterizedWebClientTest
+	void retrieveBodilessEntity(ClientHttpConnector connector) {
+		startServer(connector);
+
+		prepareResponse(response -> response
+				.setHeader("Content-Type", "application/json").setBody("{\"bar\":\"barbar\",\"foo\":\"foofoo\"}"));
+
+		Mono<ResponseEntity<Void>> result = this.webClient.get()
+				.uri("/json").accept(MediaType.APPLICATION_JSON)
+				.retrieve()
+				.toBodilessEntity();
+
+		StepVerifier.create(result)
+				.consumeNextWith(entity -> {
+					assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.OK);
+					assertThat(entity.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_JSON);
+					assertThat(entity.getHeaders().getContentLength()).isEqualTo(31);
+					assertThat(entity.getBody()).isNull();
+				})
+				.expectComplete().verify(Duration.ofSeconds(3));
+
+		expectRequestCount(1);
+		expectRequest(request -> {
+			assertThat(request.getPath()).isEqualTo("/json");
+			assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo("application/json");
+		});
+	}
+
 	@ParameterizedWebClientTest
 	void retrieveEntityWithServerError(ClientHttpConnector connector) {
 		startServer(connector);
@@ -314,6 +370,29 @@ void retrieveEntityWithServerError(ClientHttpConnector connector) {
 		});
 	}
 
+	@ParameterizedWebClientTest
+	void retrieveBodilessEntityWithServerError(ClientHttpConnector connector) {
+		startServer(connector);
+
+		prepareResponse(response -> response.setResponseCode(500)
+				.setHeader("Content-Type", "text/plain").setBody("Internal Server error"));
+
+		Mono<ResponseEntity<Void>> result = this.webClient.get()
+				.uri("/").accept(MediaType.APPLICATION_JSON)
+				.retrieve()
+				.toBodilessEntity();
+
+		StepVerifier.create(result)
+				.expectError(WebClientResponseException.class)
+				.verify(Duration.ofSeconds(3));
+
+		expectRequestCount(1);
+		expectRequest(request -> {
+			assertThat(request.getPath()).isEqualTo("/");
+			assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo("application/json");
+		});
+	}
+
 	@ParameterizedWebClientTest
 	void retrieveEntityWithServerErrorStatusHandler(ClientHttpConnector connector) {
 		startServer(connector);