Avoid DTO Constructor Expression rewriting for selection of nested properties.

We back off from rewriting String-based queries to use DTO Constructor expressions if the query selects a property that is assignable to the return type.

Closes #3862

Author: mp911de

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/AbstractStringBasedJpaQuery.java

@@ -18,12 +18,17 @@
 import jakarta.persistence.EntityManager;
 import jakarta.persistence.Query;
 
+import java.util.List;
+import java.util.Map;
 import java.util.Objects;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.expression.ValueEvaluationContextProvider;
 import org.springframework.data.jpa.repository.QueryRewriter;
+import org.springframework.data.mapping.PropertyPath;
+import org.springframework.data.mapping.PropertyReferenceException;
 import org.springframework.data.repository.query.ResultProcessor;
 import org.springframework.data.repository.query.ReturnedType;
 import org.springframework.data.repository.query.ValueExpressionDelegate;
@@ -48,7 +53,8 @@
  */
 abstract class AbstractStringBasedJpaQuery extends AbstractJpaQuery {
 
-	private final DeclaredQuery query;
+	private final StringQuery query;
+	private final Map<Class<?>, Boolean> knownProjections = new ConcurrentHashMap<>();
 	private final Lazy<DeclaredQuery> countQuery;
 	private final ValueExpressionDelegate valueExpressionDelegate;
 	private final QueryParameterSetter.QueryMetadataCache metadataCache = new QueryParameterSetter.QueryMetadataCache();
@@ -120,7 +126,7 @@ public Query doCreateQuery(JpaParametersParameterAccessor accessor) {
 
 		Sort sort = accessor.getSort();
 		ResultProcessor processor = getQueryMethod().getResultProcessor().withDynamicProjection(accessor);
-		ReturnedType returnedType = processor.getReturnedType();
+		ReturnedType returnedType = getReturnedType(processor);
 		String sortedQueryString = getSortedQueryString(sort, returnedType);
 		Query query = createJpaQuery(sortedQueryString, sort, accessor.getPageable(), returnedType);
 
@@ -131,6 +137,81 @@ public Query doCreateQuery(JpaParametersParameterAccessor accessor) {
 		return parameterBinder.get().bindAndPrepare(query, metadata, accessor);
 	}
 
+	/**
+	 * Post-process {@link ReturnedType} to determine if the query is projecting by checking the projection and property
+	 * assignability.
+	 *
+	 * @param processor
+	 * @return
+	 */
+	private ReturnedType getReturnedType(ResultProcessor processor) {
+
+		ReturnedType returnedType = processor.getReturnedType();
+		Class<?> returnedJavaType = processor.getReturnedType().getReturnedType();
+
+		if (query.isDefaultProjection() || !returnedType.isProjecting() || returnedJavaType.isInterface()
+				|| query.isNativeQuery()) {
+			return returnedType;
+		}
+
+		Boolean known = knownProjections.get(returnedJavaType);
+
+		if (known != null && known) {
+			return returnedType;
+		}
+
+		if ((known != null && !known) || returnedJavaType.isArray()) {
+			if (known == null) {
+				knownProjections.put(returnedJavaType, false);
+			}
+			return new NonProjectingReturnedType(returnedType);
+		}
+
+		String alias = query.getAlias();
+		String projection = query.getProjection();
+
+		// we can handle single-column and no function projections here only
+		if (StringUtils.hasText(projection) && (projection.indexOf(',') != -1 || projection.indexOf('(') != -1)) {
+			return returnedType;
+		}
+
+		if (StringUtils.hasText(alias) && StringUtils.hasText(projection)) {
+			alias = alias.trim();
+			projection = projection.trim();
+			if (projection.startsWith(alias + ".")) {
+				projection = projection.substring(alias.length() + 1);
+			}
+		}
+
+		if (StringUtils.hasText(projection)) {
+
+			int space = projection.indexOf(' ');
+
+			if (space != -1) {
+				projection = projection.substring(0, space);
+			}
+
+			Class<?> propertyType;
+
+			try {
+				PropertyPath from = PropertyPath.from(projection, getQueryMethod().getEntityInformation().getJavaType());
+				propertyType = from.getLeafType();
+			} catch (PropertyReferenceException ignored) {
+				propertyType = null;
+			}
+
+			if (propertyType == null
+					|| (returnedJavaType.isAssignableFrom(propertyType) || propertyType.isAssignableFrom(returnedJavaType))) {
+				knownProjections.put(returnedJavaType, false);
+				return new NonProjectingReturnedType(returnedType);
+			} else {
+				knownProjections.put(returnedJavaType, true);
+			}
+		}
+
+		return returnedType;
+	}
+
 	String getSortedQueryString(Sort sort, ReturnedType returnedType) {
 		return querySortRewriter.getSorted(query, sort, returnedType);
 	}
@@ -348,4 +429,46 @@ public int hashCode() {
 			return result;
 		}
 	}
+
+	/**
+	 * Non-projecting {@link ReturnedType} wrapper that delegates to the original {@link ReturnedType} but always returns
+	 * {@code false} for {@link #isProjecting()}. This type is to indicate that this query is not projecting, even if the
+	 * original {@link ReturnedType} was because we e.g. select a nested property and do not want DTO constructor
+	 * expression rewriting to kick in.
+	 */
+	private static class NonProjectingReturnedType extends ReturnedType {
+
+		private final ReturnedType delegate;
+
+		NonProjectingReturnedType(ReturnedType delegate) {
+			super(delegate.getDomainType());
+			this.delegate = delegate;
+		}
+
+		@Override
+		public boolean isProjecting() {
+			return false;
+		}
+
+		@Override
+		public Class<?> getReturnedType() {
+			return delegate.getReturnedType();
+		}
+
+		@Override
+		public boolean needsCustomConstruction() {
+			return false;
+		}
+
+		@Override
+		@Nullable
+		public Class<?> getTypeToRead() {
+			return delegate.getTypeToRead();
+		}
+
+		@Override
+		public List<String> getInputProperties() {
+			return delegate.getInputProperties();
+		}
+	}
 }

spring-data-jpa/src/test/java/org/springframework/data/jpa/domain/sample/Address.java

@@ -17,6 +17,8 @@
 
 import jakarta.persistence.Embeddable;
 
+import org.springframework.util.ObjectUtils;
+
 /**
  * @author Thomas Darimont
  */
@@ -52,4 +54,26 @@ public String getStreetName() {
 	public String getStreetNo() {
 		return streetNo;
 	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (!(o instanceof Address address)) {
+			return false;
+		}
+		if (!ObjectUtils.nullSafeEquals(country, address.country)) {
+			return false;
+		}
+		if (!ObjectUtils.nullSafeEquals(city, address.city)) {
+			return false;
+		}
+		if (!ObjectUtils.nullSafeEquals(streetName, address.streetName)) {
+			return false;
+		}
+		return ObjectUtils.nullSafeEquals(streetNo, address.streetNo);
+	}
+
+	@Override
+	public int hashCode() {
+		return ObjectUtils.nullSafeHash(country, city, streetName, streetNo);
+	}
 }

spring-data-jpa/src/test/java/org/springframework/data/jpa/domain/sample/Role.java

@@ -19,6 +19,8 @@
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.Id;
 
+import org.springframework.util.ObjectUtils;
+
 /**
  * Sample domain class representing roles. Mapped with XML.
  *
@@ -55,4 +57,17 @@ public String toString() {
 	public boolean isNew() {
 		return id == null;
 	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (!(o instanceof Role role)) {
+			return false;
+		}
+		return ObjectUtils.nullSafeEquals(id, role.id);
+	}
+
+	@Override
+	public int hashCode() {
+		return ObjectUtils.nullSafeHash(id);
+	}
 }

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/UserRepositoryFinderTests.java

@@ -15,10 +15,8 @@
  */
 package org.springframework.data.jpa.repository;
 
-import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
-import static org.springframework.data.domain.Sort.Direction.ASC;
-import static org.springframework.data.domain.Sort.Direction.DESC;
+import static org.assertj.core.api.Assertions.*;
+import static org.springframework.data.domain.Sort.Direction.*;
 
 import jakarta.persistence.EntityManager;
 
@@ -33,6 +31,7 @@
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
+
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.data.domain.Limit;
@@ -43,6 +42,7 @@
 import org.springframework.data.domain.Slice;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.domain.Window;
+import org.springframework.data.jpa.domain.sample.Address;
 import org.springframework.data.jpa.domain.sample.Role;
 import org.springframework.data.jpa.domain.sample.User;
 import org.springframework.data.jpa.provider.PersistenceProvider;
@@ -422,6 +422,11 @@ void dtoProjectionShouldApplyConstructorExpressionRewriting() {
 
 		assertThat(dtos).flatExtracting(UserRepository.UserExcerpt::firstname) //
 				.contains("Dave", "Carter", "Oliver August");
+
+		dtos = userRepository.findRecordProjectionWithFunctions();
+
+		assertThat(dtos).flatExtracting(UserRepository.UserExcerpt::lastname) //
+				.contains("matthews", "beauford");
 	}
 
 	@Test // GH-3076
@@ -442,6 +447,29 @@ void dynamicDtoProjection() {
 				.contains("Dave", "Carter", "Oliver August");
 	}
 
+	@Test // GH-3862
+	void shouldNotRewritePrimitiveSelectionToDtoProjection() {
+
+		oliver.setAge(28);
+		em.persist(oliver);
+
+		assertThat(userRepository.findAgeByAnnotatedQuery(oliver.getEmailAddress())).contains(28);
+	}
+
+	@Test // GH-3862
+	void shouldNotRewritePropertySelectionToDtoProjection() {
+
+		Address address = new Address("DE", "Dresden", "some street", "12345");
+		dave.setAddress(address);
+		userRepository.save(dave);
+		em.flush();
+		em.clear();
+
+		assertThat(userRepository.findAddressByAnnotatedQuery(dave.getEmailAddress())).contains(address);
+		assertThat(userRepository.findCityByAnnotatedQuery(dave.getEmailAddress())).contains("Dresden");
+		assertThat(userRepository.findRolesByAnnotatedQuery(dave.getEmailAddress())).contains(singer);
+	}
+
 	@Test // GH-3076
 	void dtoProjectionWithEntityAndAggregatedValue() {
 

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java

@@ -455,7 +455,6 @@ void testOverwritingFinder() {
 
 	@Test
 	void testUsesQueryAnnotation() {
-
 		assertThat(repository.findByAnnotatedQuery("[email protected]")).isNull();
 	}
 

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/sample/UserRepository.java

@@ -37,6 +37,7 @@
 import org.springframework.data.domain.Slice;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.domain.Window;
+import org.springframework.data.jpa.domain.sample.Address;
 import org.springframework.data.jpa.domain.sample.Role;
 import org.springframework.data.jpa.domain.sample.SpecialUser;
 import org.springframework.data.jpa.domain.sample.User;
@@ -723,12 +724,39 @@ List<String> findAllAndSortByFunctionResultNamedParameter(@Param("namedParameter
 	@Query("select u from User u")
 	List<UserExcerpt> findRecordProjection();
 
+	@Query("select u.firstname, LOWER(u.lastname) from User u")
+	List<UserExcerpt> findRecordProjectionWithFunctions();
+
 	@Query("select u from User u")
 	<T> List<T> findRecordProjection(Class<T> projectionType);
 
 	@Query("select u.firstname, u.lastname from User u")
 	List<UserExcerpt> findMultiselectRecordProjection();
 
+	/**
+	 * Retrieves a user age by email.
+	 */
+	@Query("select u.age from User u where u.emailAddress = ?1")
+	Optional<Integer> findAgeByAnnotatedQuery(String emailAddress);
+
+	/**
+	 * Retrieves a user address by email.
+	 */
+	@Query("select u.address from User u where u.emailAddress = ?1")
+	Optional<Address> findAddressByAnnotatedQuery(String emailAddress);
+
+	/**
+	 * Retrieves a user roles by email.
+	 */
+	@Query("select u.roles from User u where u.emailAddress = ?1")
+	Set<Role> findRolesByAnnotatedQuery(String emailAddress);
+
+	/**
+	 * Retrieves a user address city by email.
+	 */
+	@Query("select u.address.city from User u where u.emailAddress = ?1")
+	String findCityByAnnotatedQuery(String emailAddress);
+
 	@UserRoleCountProjectingQuery
 	List<UserRoleCountDtoProjection> dtoProjectionEntityAndAggregatedValue();