#1134 - Make sure we don't accidentally drop customizations made to W…

…ebClient.

We now use the API introduced in Spring Framework 5.2.2 to customize a WebClient to add hypermedia related en- and decoders without dropping customizations potentially made to the WebClient instance.

src/main/java/org/springframework/hateoas/config/WebClientConfigurer.java

@@ -15,17 +15,19 @@
  */
 package org.springframework.hateoas.config;
 
-import lombok.RequiredArgsConstructor;
-
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Consumer;
 
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.codec.Decoder;
 import org.springframework.core.codec.Encoder;
 import org.springframework.hateoas.config.EnableHypermediaSupport.HypermediaType;
+import org.springframework.http.codec.ClientCodecConfigurer;
+import org.springframework.http.codec.CodecConfigurer.CustomCodecs;
 import org.springframework.http.codec.json.Jackson2JsonDecoder;
 import org.springframework.http.codec.json.Jackson2JsonEncoder;
+import org.springframework.util.Assert;
 import org.springframework.util.MimeType;
 import org.springframework.web.reactive.function.client.ExchangeStrategies;
 import org.springframework.web.reactive.function.client.WebClient;
@@ -36,40 +38,57 @@
  * Assembles {@link ExchangeStrategies} needed to wire a {@link WebClient} with hypermedia support.
  *
  * @author Greg Turnquist
+ * @author Oliver Drotbohm
  * @since 1.0
  */
 @Configuration
-@RequiredArgsConstructor
 public class WebClientConfigurer {
 
-	private final ObjectMapper mapper;
-	private final List<HypermediaMappingInformation> hypermediaTypes;
+	Consumer<ClientCodecConfigurer> configurer;
 
 	/**
-	 * Return a set of {@link ExchangeStrategies} driven by registered {@link HypermediaType}s.
+	 * Creates a new {@link WebClientConfigurer} for the given {@link ObjectMapper} and
+	 * {@link HypermediaMappingInformation}s.
 	 *
-	 * @return a collection of {@link Encoder}s and {@link Decoder} assembled into a {@link ExchangeStrategies}.
+	 * @param mapper must not be {@literal null}.
+	 * @param hypermediaTypes must not be {@literal null}.
 	 */
-	public ExchangeStrategies hypermediaExchangeStrategies() {
+	public WebClientConfigurer(ObjectMapper mapper, List<HypermediaMappingInformation> hypermediaTypes) {
+
+		Assert.notNull(mapper, "ObjectMapper must not be null!");
+		Assert.notNull(hypermediaTypes, "HypermediaMappingInformations must not be null!");
 
 		List<Encoder<?>> encoders = new ArrayList<>();
 		List<Decoder<?>> decoders = new ArrayList<>();
 
-		this.hypermediaTypes.forEach(hypermedia -> {
+		hypermediaTypes.forEach(hypermedia -> {
 
-			ObjectMapper objectMapper = hypermedia.configureObjectMapper(this.mapper.copy());
+			ObjectMapper objectMapper = hypermedia.configureObjectMapper(mapper.copy());
 			MimeType[] mimeTypes = hypermedia.getMediaTypes().toArray(new MimeType[0]);
 
 			encoders.add(new Jackson2JsonEncoder(objectMapper, mimeTypes));
 			decoders.add(new Jackson2JsonDecoder(objectMapper, mimeTypes));
 		});
 
-		return ExchangeStrategies.builder().codecs(clientCodecConfigurer -> {
+		this.configurer = it -> {
 
-			encoders.forEach(encoder -> clientCodecConfigurer.customCodecs().encoder(encoder));
-			decoders.forEach(decoder -> clientCodecConfigurer.customCodecs().decoder(decoder));
+			CustomCodecs codecs = it.customCodecs();
 
-		}).build();
+			encoders.forEach(codecs::encoder);
+			decoders.forEach(codecs::decoder);
+		};
+	}
+
+	/**
+	 * Return a set of {@link ExchangeStrategies} driven by registered {@link HypermediaType}s.
+	 *
+	 * @return a collection of {@link Encoder}s and {@link Decoder} assembled into a {@link ExchangeStrategies}.
+	 */
+	public ExchangeStrategies hypermediaExchangeStrategies() {
+
+		return ExchangeStrategies.builder() //
+				.codecs(configurer) //
+				.build();
 	}
 
 	/**
@@ -79,6 +98,9 @@ public ExchangeStrategies hypermediaExchangeStrategies() {
 	 * @return mutated webClient with hypermedia support.
 	 */
 	public WebClient registerHypermediaTypes(WebClient webClient) {
-		return webClient.mutate().exchangeStrategies(hypermediaExchangeStrategies()).build();
+
+		return webClient.mutate() //
+				.exchangeStrategies(it -> it.codecs(configurer)) //
+				.build();
 	}
 }

src/test/java/org/springframework/hateoas/config/CustomHypermediaWebFluxTest.java

@@ -19,11 +19,12 @@
 import static org.springframework.hateoas.support.CustomHypermediaType.*;
 import static org.springframework.hateoas.support.MappingUtils.*;
 
+import reactor.core.publisher.Mono;
+
 import java.io.IOException;
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import reactor.core.publisher.Mono;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -55,7 +56,7 @@ void setUp() {
 
 		this.testClient = WebTestClient.bindToApplicationContext(ctx).build() //
 				.mutate() //
-				.exchangeStrategies(webClientConfigurer.hypermediaExchangeStrategies()) //
+				.exchangeStrategies(it -> it.codecs(webClientConfigurer.configurer)) //
 				.build();
 	}