Fix issue where links are wrongly serialized when MappingJacksonValue is used as a return type

pom.xml

@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-rest-parent</artifactId>
-	<version>5.2.0-SNAPSHOT</version>
+	<version>5.2.0-1544-SNAPSHOT</version>
 	<packaging>pom</packaging>
 
 	<name>Spring Data REST</name>

spring-data-rest-core/pom.xml

@@ -11,7 +11,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-rest-parent</artifactId>
-		<version>5.2.0-SNAPSHOT</version>
+		<version>5.2.0-1544-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-rest-distribution/pom.xml

@@ -13,7 +13,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-rest-parent</artifactId>
-		<version>5.2.0-SNAPSHOT</version>
+		<version>5.2.0-1544-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-rest-hal-explorer/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-rest-parent</artifactId>
-		<version>5.2.0-SNAPSHOT</version>
+		<version>5.2.0-1544-SNAPSHOT</version>
 	</parent>
 
 	<artifactId>spring-data-rest-hal-explorer</artifactId>

spring-data-rest-tests/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-rest-parent</artifactId>
-		<version>5.2.0-SNAPSHOT</version>
+		<version>5.2.0-1544-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-rest-tests/spring-data-rest-tests-core/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-rest-tests</artifactId>
-		<version>5.2.0-SNAPSHOT</version>
+		<version>5.2.0-1544-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
@@ -21,7 +21,7 @@
 		<dependency>
 			<groupId>org.springframework.data</groupId>
 			<artifactId>spring-data-rest-webmvc</artifactId>
-			<version>5.2.0-SNAPSHOT</version>
+			<version>5.2.0-1544-SNAPSHOT</version>
 		</dependency>
 
 	</dependencies>

spring-data-rest-tests/spring-data-rest-tests-jpa/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-rest-tests</artifactId>
-		<version>5.2.0-SNAPSHOT</version>
+		<version>5.2.0-1544-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
@@ -21,7 +21,7 @@
 		<dependency>
 			<groupId>org.springframework.data</groupId>
 			<artifactId>spring-data-rest-tests-core</artifactId>
-			<version>5.2.0-SNAPSHOT</version>
+			<version>5.2.0-1544-SNAPSHOT</version>
 			<type>test-jar</type>
 		</dependency>
 

spring-data-rest-tests/spring-data-rest-tests-mongodb/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-rest-tests</artifactId>
-		<version>5.2.0-SNAPSHOT</version>
+		<version>5.2.0-1544-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
@@ -33,7 +33,7 @@
 		<dependency>
 			<groupId>org.springframework.data</groupId>
 			<artifactId>spring-data-rest-tests-core</artifactId>
-			<version>5.2.0-SNAPSHOT</version>
+			<version>5.2.0-1544-SNAPSHOT</version>
 			<type>test-jar</type>
 		</dependency>
 

spring-data-rest-tests/spring-data-rest-tests-security/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-rest-tests</artifactId>
-		<version>5.2.0-SNAPSHOT</version>
+		<version>5.2.0-1544-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
@@ -22,7 +22,7 @@
 		<dependency>
 			<groupId>org.springframework.data</groupId>
 			<artifactId>spring-data-rest-tests-core</artifactId>
-			<version>5.2.0-SNAPSHOT</version>
+			<version>5.2.0-1544-SNAPSHOT</version>
 			<type>test-jar</type>
 		</dependency>
 

spring-data-rest-tests/spring-data-rest-tests-shop/pom.xml

@@ -4,7 +4,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-rest-tests</artifactId>
-		<version>5.2.0-SNAPSHOT</version>
+		<version>5.2.0-1544-SNAPSHOT</version>
 	</parent>
 	<name>Spring Data REST Tests - Shop</name>
 	<artifactId>spring-data-rest-tests-shop</artifactId>

spring-data-rest-webmvc/pom.xml

@@ -11,7 +11,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-rest-parent</artifactId>
-		<version>5.2.0-SNAPSHOT</version>
+		<version>5.2.0-1544-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/config/MappingJacksonValueResponseBodyAdvice.java

@@ -0,0 +1,139 @@
+/*
+ * Copyright 2024-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.rest.webmvc.config;
+
+import tools.jackson.databind.ser.FilterProvider;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.jspecify.annotations.Nullable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.core.MethodParameter;
+import org.springframework.http.MediaType;
+import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.http.server.ServerHttpRequest;
+import org.springframework.http.server.ServerHttpResponse;
+import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;
+
+/**
+ * {@link ResponseBodyAdvice} that transparently handles
+ * {@link org.springframework.http.converter.json.MappingJacksonValue} return values from
+ * {@link org.springframework.data.rest.webmvc.RepositoryRestController} methods. In Spring Framework 7,
+ * {@code MappingJacksonValue} is no longer supported as a direct return type by the Jackson message converters
+ * (which now use Jackson 3 / {@code tools.jackson}). This advice unwraps the inner value so that the HAL
+ * message converters can serialize it correctly, producing proper {@code _links} output.
+ *
+ * <p>Any {@link FilterProvider} set on the {@code MappingJacksonValue} is propagated as a Jackson 3 converter
+ * hint provided it is already an instance of {@link tools.jackson.databind.ser.FilterProvider}. If a legacy
+ * Jackson 2 ({@code com.fasterxml.jackson.databind.ser.FilterProvider}) instance is detected, a warning is
+ * logged and the filter is skipped; callers should migrate to Jackson 3's
+ * {@link tools.jackson.databind.ser.std.SimpleFilterProvider} instead.
+ *
+ * <p>Serialization views set via {@code MappingJacksonValue#setSerializationView(Class)} are always forwarded
+ * as hints regardless of the Jackson version.
+ *
+ * @author Steve Rutherford
+ * @see ResponseBodyAdvice#determineWriteHints(Object, MethodParameter, MediaType, Class)
+ */
+@SuppressWarnings({ "deprecation", "removal" })
+class MappingJacksonValueResponseBodyAdvice implements ResponseBodyAdvice<Object> {
+
+	private static final Logger logger = LoggerFactory.getLogger(MappingJacksonValueResponseBodyAdvice.class);
+
+	/**
+	 * Thread-local storage for hints extracted from a {@code MappingJacksonValue} during
+	 * {@link #beforeBodyWrite}. These are consumed in {@link #determineWriteHints}, which is
+	 * called immediately after on the same thread by the Spring MVC infrastructure.
+	 */
+	private static final ThreadLocal<Map<String, Object>> PENDING_HINTS = new ThreadLocal<>();
+
+	/**
+	 * The hint key used by {@code AbstractJacksonHttpMessageConverter} for a Jackson 3
+	 * {@link FilterProvider}. The key is the fully-qualified class name of
+	 * {@link tools.jackson.databind.ser.FilterProvider}.
+	 */
+	private static final String FILTER_PROVIDER_HINT = FilterProvider.class.getName();
+
+	/**
+	 * The hint key used by {@code AbstractJacksonHttpMessageConverter} for a JSON serialization view.
+	 * The key is the fully-qualified class name of {@link Class}.
+	 */
+	private static final String JSON_VIEW_HINT = Class.class.getName();
+
+	@Override
+	public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
+		return org.springframework.http.converter.json.MappingJacksonValue.class
+				.isAssignableFrom(returnType.getParameterType())
+				|| hasWrappedMappingJacksonValueGeneric(returnType);
+	}
+
+	@Override
+	public @Nullable Object beforeBodyWrite(@Nullable Object body, MethodParameter returnType,
+			MediaType selectedContentType, Class<? extends HttpMessageConverter<?>> selectedConverterType,
+			ServerHttpRequest request, ServerHttpResponse response) {
+
+		if (!(body instanceof org.springframework.http.converter.json.MappingJacksonValue wrapper)) {
+			return body;
+		}
+
+		Map<String, Object> hints = new HashMap<>();
+
+		Object rawFilters = wrapper.getFilters();
+		if (rawFilters != null) {
+			if (rawFilters instanceof FilterProvider jackson3Filters) {
+				// The filter is already a Jackson 3 FilterProvider — pass it as a hint
+				hints.put(FILTER_PROVIDER_HINT, jackson3Filters);
+			} else {
+				logger.warn("MappingJacksonValue contains a Jackson 2 FilterProvider ({}), which is incompatible "
+						+ "with the Jackson 3 message converters used by Spring Data REST. The filter will be ignored. "
+						+ "Migrate to tools.jackson.databind.ser.std.SimpleFilterProvider instead.",
+						rawFilters.getClass().getName());
+			}
+		}
+
+		Class<?> serializationView = wrapper.getSerializationView();
+		if (serializationView != null) {
+			hints.put(JSON_VIEW_HINT, serializationView);
+		}
+
+		if (!hints.isEmpty()) {
+			PENDING_HINTS.set(hints);
+		}
+
+		return wrapper.getValue();
+	}
+
+	@Override
+	public @Nullable Map<String, Object> determineWriteHints(@Nullable Object body, MethodParameter returnType,
+			MediaType selectedContentType, Class<? extends HttpMessageConverter<?>> selectedConverterType) {
+
+		Map<String, Object> hints = PENDING_HINTS.get();
+		PENDING_HINTS.remove();
+		return hints;
+	}
+
+	/**
+	 * Checks whether the return type is a generic wrapper (e.g. {@code ResponseEntity<MappingJacksonValue>})
+	 * whose type argument is {@code MappingJacksonValue}.
+	 */
+	private static boolean hasWrappedMappingJacksonValueGeneric(MethodParameter returnType) {
+
+		Class<?> nested = returnType.nested().getNestedParameterType();
+		return org.springframework.http.converter.json.MappingJacksonValue.class.isAssignableFrom(nested);
+	}
+}

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/config/RepositoryRestMvcConfiguration.java

@@ -163,6 +163,7 @@
  * @author Mark Paluch
  * @author Christoph Strobl
  * @author Will Fleury
+ * @author Steve Rutherford
  */
 @Configuration(proxyBeanMethods = false)
 @EnableHypermediaSupport(type = { HypermediaType.HAL, HypermediaType.HAL_FORMS })
@@ -657,6 +658,7 @@ public RequestMappingHandlerAdapter repositoryExporterHandlerAdapter(
 		handlerAdapter.setMessageConverters(defaultMessageConverters);
 
 		List<ResponseBodyAdvice<?>> advices = new ArrayList<>();
+		advices.add(new MappingJacksonValueResponseBodyAdvice());
 		advices.add(new HalFormsAdaptingResponseBodyAdvice<>());
 
 		if (repositoryRestConfiguration.getMetadataConfiguration().alpsEnabled()) {