Refine projections.

Author: mp911de

src/main/java/org/springframework/data/web/JsonProjectingMethodInterceptorFactory.java

@@ -131,18 +131,27 @@ private static boolean hasJsonPathAnnotation(Class<?> type) {
 		return false;
 	}
 
-	private static class InputMessageProjecting implements MethodInterceptor {
-
-		private final DocumentContext context;
-
-		public InputMessageProjecting(DocumentContext context) {
-			this.context = context;
-		}
+	private record InputMessageProjecting(DocumentContext context) implements MethodInterceptor {
 
 		@Override
 		public @Nullable Object invoke(MethodInvocation invocation) throws Throwable {
 
 			Method method = invocation.getMethod();
+
+			switch (method.getName()) {
+				case "equals" -> {
+					// Only consider equal when proxies are identical.
+					return (invocation.getThis() == invocation.getArguments()[0]);
+				}
+				case "hashCode" -> {
+					// Use hashCode of EntityManager proxy.
+					return context.hashCode();
+				}
+				case "toString" -> {
+					return context.jsonString();
+				}
+			}
+
 			TypeInformation<?> returnType = TypeInformation.fromReturnTypeOf(method);
 			ResolvableType type = ResolvableType.forMethodReturnType(method);
 			boolean isCollectionResult = type.getRawClass() != null && Collection.class.isAssignableFrom(type.getRawClass());

src/main/java/org/springframework/data/web/ProjectingJacksonHttpMessageConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2025 the original author or authors.
+ * Copyright 2025 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.
@@ -56,6 +56,7 @@
  * {@link HttpMessageConverter} implementation to enable projected JSON binding to interfaces annotated with
  * {@link ProjectedPayload}.
  *
+ * @author Mark Paluch
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @soundtrack Richard Spaven - Ice Is Nice (Spaven's 5ive)
@@ -115,28 +116,38 @@ public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
 	}
 
 	@Override
-	public boolean canRead(ResolvableType type, @Nullable MediaType mediaType) {
+	protected boolean supports(Class<?> clazz) {
 
-		if (!canRead(mediaType)) {
-			return false;
-		}
+		if (clazz.isInterface()) {
 
-		Class<?> rawType = type.resolve();
+			Boolean result = supportedTypesCache.get(clazz);
 
-		if (rawType == null) {
-			return false;
-		}
+			if (result != null) {
+				return result;
+			}
 
-		Boolean result = supportedTypesCache.get(rawType);
+			result = AnnotationUtils.findAnnotation(clazz, ProjectedPayload.class) != null;
+			supportedTypesCache.put(clazz, result);
 
-		if (result != null) {
 			return result;
 		}
 
-		result = rawType.isInterface() && AnnotationUtils.findAnnotation(rawType, ProjectedPayload.class) != null;
-		supportedTypesCache.put(rawType, result);
+		return false;
+	}
+
+	@Override
+	public boolean canRead(ResolvableType type, @Nullable MediaType mediaType) {
+
+		if (!super.canRead(type, mediaType)) {
+			return false;
+		}
+
+		Class<?> clazz = type.resolve();
+		if (clazz == null) {
+			return false;
+		}
 
-		return result;
+		return supports(clazz);
 	}
 
 	@Override

src/main/java/org/springframework/data/web/config/SpringDataWebConfiguration.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.web.config;
 
+import java.util.ArrayList;
 import java.util.List;
 
 import org.jspecify.annotations.Nullable;
@@ -39,6 +40,7 @@
 import org.springframework.data.web.XmlBeamHttpMessageConverter;
 import org.springframework.format.FormatterRegistry;
 import org.springframework.format.support.FormattingConversionService;
+import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.HttpMessageConverters;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -154,6 +156,17 @@ public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentRes
 	@Override
 	public void configureMessageConverters(HttpMessageConverters.Builder builder) {
 
+		List<HttpMessageConverter<?>> converters = new ArrayList<>();
+		configureMessageConverters(converters);
+
+		for (HttpMessageConverter<?> converter : converters) {
+			builder.additionalMessageConverter(converter);
+		}
+	}
+
+	@Override
+	public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
+
 		if (ClassUtils.isPresent("com.jayway.jsonpath.DocumentContext", context.getClassLoader())) {
 
 			if (ClassUtils.isPresent("tools.jackson.databind.ObjectReader", context.getClassLoader())) {
@@ -165,7 +178,7 @@ public void configureMessageConverters(HttpMessageConverters.Builder builder) {
 				converter.setBeanFactory(context);
 				forwardBeanClassLoader(converter);
 
-				builder.additionalMessageConverter(converter);
+				converters.add(0, converter);
 			} else if (ClassUtils.isPresent("com.fasterxml.jackson.databind.ObjectMapper", context.getClassLoader())) {
 
 				ObjectMapper mapper = context.getBeanProvider(ObjectMapper.class).getIfUnique(ObjectMapper::new);
@@ -174,13 +187,13 @@ public void configureMessageConverters(HttpMessageConverters.Builder builder) {
 				converter.setBeanFactory(context);
 				forwardBeanClassLoader(converter);
 
-				builder.additionalMessageConverter(converter);
+				converters.add(0, converter);
 			}
 		}
 
 		if (ClassUtils.isPresent("org.xmlbeam.XBProjector", context.getClassLoader())) {
 
-			builder.additionalMessageConverter(context.getBeanProvider(XmlBeamHttpMessageConverter.class) //
+			converters.add(0, context.getBeanProvider(XmlBeamHttpMessageConverter.class) //
 					.getIfAvailable(XmlBeamHttpMessageConverter::new));
 		}
 	}

src/test/java/org/springframework/data/web/ProjectingJacksonHttpMessageConverterUnitTests.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2025 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.web;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.core.ResolvableType;
+import org.springframework.http.MediaType;
+
+/**
+ * Unit tests for {@link ProjectingJacksonHttpMessageConverter}.
+ *
+ * @author Oliver Gierke
+ * @author Mark Paluch
+ */
+class ProjectingJacksonHttpMessageConverterUnitTests {
+
+	ProjectingJacksonHttpMessageConverter converter = new ProjectingJacksonHttpMessageConverter();
+	MediaType ANYTHING_JSON = MediaType.parseMediaType("application/*+json");
+
+	@Test // DATCMNS-885
+	void canReadJsonIntoAnnotatedInterface() {
+		assertThat(converter.canRead(SampleInterface.class, ANYTHING_JSON)).isTrue();
+	}
+
+	@Test // DATCMNS-885
+	void cannotReadUnannotatedInterface() {
+		assertThat(converter.canRead(UnannotatedInterface.class, ANYTHING_JSON)).isFalse();
+	}
+
+	@Test // DATCMNS-885
+	void cannotReadClass() {
+		assertThat(converter.canRead(SampleClass.class, ANYTHING_JSON)).isFalse();
+	}
+
+	@Test // DATACMNS-972
+	void doesNotConsiderTypeVariableBoundTo() throws Throwable {
+
+		var method = BaseController.class.getDeclaredMethod("createEntity", AbstractDto.class);
+
+		assertThat(converter.canRead(ResolvableType.forMethodParameter(method, 0), ANYTHING_JSON)).isFalse();
+	}
+
+	@Test // DATACMNS-972
+	void genericTypeOnConcreteOne() throws Throwable {
+
+		var method = ConcreteController.class.getMethod("createEntity", AbstractDto.class);
+
+		assertThat(converter.canRead(ResolvableType.forMethodParameter(method, 0), ANYTHING_JSON)).isFalse();
+	}
+
+	@ProjectedPayload
+	interface SampleInterface {}
+
+	interface UnannotatedInterface {}
+
+	class SampleClass {}
+
+	class AbstractDto {}
+
+	abstract class BaseController<D extends AbstractDto> {
+		public void createEntity(D dto) {}
+	}
+
+	class ConcreteController extends BaseController<AbstractDto> {}
+}