Apply hints for pagined projections on fetchable Querydsl queries.

When using Querydsl predicates to build a fluent query, be sure to apply the projection hint that generates a fetch graph.

Resolves #2820.
Original pull request: #2827.

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/support/FetchableFluentQueryByPredicate.java

@@ -15,6 +15,8 @@
  */
 package org.springframework.data.jpa.repository.support;
 
+import jakarta.persistence.EntityManager;
+
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -23,8 +25,6 @@ import java.util.function.BiFunction;
 import java.util.function.Function;
 import java.util.stream.Stream;
 
-import jakarta.persistence.EntityManager;
-
 import org.springframework.dao.IncorrectResultSizeDataAccessException;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.PageImpl;
@@ -69,8 +69,7 @@ class FetchableFluentQueryByPredicate<S, R> extends FluentQuerySupport<S, R> imp
 	private FetchableFluentQueryByPredicate(Predicate predicate, Class<S> entityType, Class<R> resultType, Sort sort,
 			Collection<String> properties, Function<Sort, AbstractJPAQuery<?, ?>> finder,
 			BiFunction<Sort, Pageable, AbstractJPAQuery<?, ?>> pagedFinder, Function<Predicate, Long> countOperation,
-			Function<Predicate, Boolean> existsOperation,
-			EntityManager entityManager) {
+			Function<Predicate, Boolean> existsOperation, EntityManager entityManager) {
 
 		super(resultType, sort, properties, entityType);
 		this.predicate = predicate;
@@ -175,8 +174,13 @@ class FetchableFluentQueryByPredicate<S, R> extends FluentQuerySupport<S, R> imp
 
 	private Page<R> readPage(Pageable pageable) {
 
-		AbstractJPAQuery<?, ?> pagedQuery = pagedFinder.apply(sort, pageable);
-		List<R> paginatedResults = convert(pagedQuery.fetch());
+		AbstractJPAQuery<?, ?> query = pagedFinder.apply(sort, pageable);
+
+		if (!properties.isEmpty()) {
+			query.setHint(EntityGraphFactory.HINT, EntityGraphFactory.create(entityManager, entityType, properties));
+		}
+
+		List<R> paginatedResults = convert(query.fetch());
 
 		return PageableExecutionUtils.getPage(paginatedResults, pageable, () -> countOperation.apply(predicate));
 	}

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

@@ -15,18 +15,17 @@
  */
 package org.springframework.data.jpa.repository;
 
-import static java.util.Arrays.asList;
+import static java.util.Arrays.*;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
-import static org.springframework.data.domain.Example.of;
+import static org.springframework.data.domain.Example.*;
 import static org.springframework.data.domain.ExampleMatcher.GenericPropertyMatcher;
 import static org.springframework.data.domain.ExampleMatcher.StringMatcher;
 import static org.springframework.data.domain.ExampleMatcher.matching;
-import static org.springframework.data.domain.Sort.Direction.ASC;
-import static org.springframework.data.domain.Sort.Direction.DESC;
+import static org.springframework.data.domain.Sort.Direction.*;
+import static org.springframework.data.jpa.domain.Specification.*;
 import static org.springframework.data.jpa.domain.Specification.not;
-import static org.springframework.data.jpa.domain.Specification.where;
 import static org.springframework.data.jpa.domain.sample.UserSpecifications.userHasAgeLess;
 import static org.springframework.data.jpa.domain.sample.UserSpecifications.userHasFirstname;
 import static org.springframework.data.jpa.domain.sample.UserSpecifications.userHasFirstnameLike;
@@ -75,6 +74,7 @@ import org.springframework.data.domain.Sort.Direction;
 import org.springframework.data.domain.Sort.Order;
 import org.springframework.data.jpa.domain.Specification;
 import org.springframework.data.jpa.domain.sample.Address;
+import org.springframework.data.jpa.domain.sample.QUser;
 import org.springframework.data.jpa.domain.sample.Role;
 import org.springframework.data.jpa.domain.sample.SpecialUser;
 import org.springframework.data.jpa.domain.sample.User;
@@ -2444,6 +2444,47 @@ class UserRepositoryTests {
 				);
 	}
 
+	@Test // GH-2820
+	void findByFluentPredicateWithProjectionAndPageRequest() {
+
+		flushTestUsers();
+		em.clear();
+
+		Page<User> users = repository.findBy(QUser.user.firstname.contains("v"), q -> q //
+				.project("firstname") //
+				.page(PageRequest.of(0, 10)));
+
+		assertThat(users).extracting(User::getFirstname).containsExactlyInAnyOrder(firstUser.getFirstname(),
+				thirdUser.getFirstname(), fourthUser.getFirstname());
+	}
+
+	@Test // GH-2820
+	void findByFluentPredicateWithProjectionAndAll() {
+
+		flushTestUsers();
+		em.clear();
+
+		List<User> users = repository.findBy(QUser.user.firstname.contains("v"), q -> q //
+				.project("firstname") //
+				.all());
+
+		assertThat(users).extracting(User::getFirstname).containsExactlyInAnyOrder(firstUser.getFirstname(),
+				thirdUser.getFirstname(), fourthUser.getFirstname());
+	}
+
+	@Test // GH-2820
+	void findByFluentPredicateWithPageRequest() {
+
+		flushTestUsers();
+		em.clear();
+
+		Page<User> users = repository.findBy(QUser.user.firstname.contains("v"), q -> q //
+				.page(PageRequest.of(0, 10)));
+
+		assertThat(users).extracting(User::getFirstname).containsExactlyInAnyOrder(firstUser.getFirstname(),
+				thirdUser.getFirstname(), fourthUser.getFirstname());
+	}
+
 	@Test // GH-2274
 	void findByFluentSpecificationWithCollectionPropertyPathsDoesntLoadUnrequestedPaths() {
 

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

@@ -18,15 +18,29 @@ package org.springframework.data.jpa.repository.sample;
 import jakarta.persistence.EntityManager;
 import jakarta.persistence.QueryHint;
 
-import java.util.*;
+import java.util.Collection;
+import java.util.Date;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
 import java.util.stream.Stream;
 
-import org.springframework.data.domain.*;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Slice;
+import org.springframework.data.domain.Sort;
 import org.springframework.data.jpa.domain.sample.Role;
 import org.springframework.data.jpa.domain.sample.SpecialUser;
 import org.springframework.data.jpa.domain.sample.User;
-import org.springframework.data.jpa.repository.*;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.jpa.repository.QueryHints;
 import org.springframework.data.jpa.repository.query.Procedure;
+import org.springframework.data.querydsl.ListQuerydslPredicateExecutor;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.query.Param;
 import org.springframework.transaction.annotation.Transactional;
@@ -45,8 +59,8 @@ import org.springframework.transaction.annotation.Transactional;
  * @author Diego Krupitza
  * @author Geoffrey Deremetz
  */
-public interface UserRepository
-		extends JpaRepository<User, Integer>, JpaSpecificationExecutor<User>, UserRepositoryCustom {
+public interface UserRepository extends JpaRepository<User, Integer>, JpaSpecificationExecutor<User>,
+		UserRepositoryCustom, ListQuerydslPredicateExecutor<User> {
 
 	/**
 	 * Retrieve users by their lastname. The finder {@literal User.findByLastname} is declared in

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

@@ -32,8 +32,6 @@ import org.springframework.data.querydsl.EntityPathResolver;
 import org.springframework.data.querydsl.SimpleEntityPathResolver;
 import org.springframework.test.util.ReflectionTestUtils;
 
-import com.querydsl.core.types.EntityPath;
-
 /**
  * Unit tests for {@link EntityPathResolver} related tests on {@link JpaRepositoryFactoryBean}.
  *
@@ -47,14 +45,7 @@ class JpaRepositoryFactoryBeanEntityPathResolverIntegrationTests {
 	@EnableJpaRepositories(basePackageClasses = UserRepository.class, //
 			includeFilters = @Filter(type = FilterType.ASSIGNABLE_TYPE, classes = UserRepository.class))
 	static class BaseConfig {
-
-		static final EntityPathResolver RESOLVER = new EntityPathResolver() {
-
-			@Override
-			public <T> EntityPath<T> createPath(Class<T> domainClass) {
-				return null;
-			}
-		};
+		static final EntityPathResolver RESOLVER = SimpleEntityPathResolver.INSTANCE;
 	}
 
 	@Configuration