Add support for returning Streamable from AOT repository methods.

Closes #4070

Author: mp911de

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/aot/JpaCodeBlocks.java

@@ -48,6 +48,7 @@
 import org.springframework.data.repository.aot.generate.AotQueryMethodGenerationContext;
 import org.springframework.data.repository.aot.generate.MethodReturn;
 import org.springframework.data.support.PageableExecutionUtils;
+import org.springframework.data.util.Streamable;
 import org.springframework.javapoet.CodeBlock;
 import org.springframework.javapoet.CodeBlock.Builder;
 import org.springframework.javapoet.TypeName;
@@ -703,8 +704,12 @@ public CodeBlock build() {
 						context.fieldNameOf(EntityManager.class));
 
 				if (collectionQuery) {
-					builder.addStatement("return ($T) $L", List.class, context.localVariable("resultList"));
 
+					if (isStreamable(methodReturn)) {
+						builder.addStatement("return ($1T) $1T.of($2L)", Streamable.class, context.localVariable("resultList"));
+					} else {
+						builder.addStatement("return ($T) $L", List.class, context.localVariable("resultList"));
+					}
 				} else if (returnCount) {
 					builder.addStatement("return $T.valueOf($L.size())",
 							ClassUtils.resolvePrimitiveIfNecessary(methodReturn.getActualReturnClass()),
@@ -770,7 +775,13 @@ public CodeBlock build() {
 				} else {
 
 					if (queryMethod.isCollectionQuery()) {
-						builder.addStatement("return ($T) $L.getResultList()", methodReturn.getTypeName(), queryVariableName);
+
+						if (isStreamable(methodReturn)) {
+							builder.addStatement("return ($T) $T.of($L.getResultList())", methodReturn.getTypeName(),
+									Streamable.class, queryVariableName);
+						} else {
+							builder.addStatement("return ($T) $L.getResultList()", methodReturn.getTypeName(), queryVariableName);
+						}
 					} else if (queryMethod.isStreamQuery()) {
 						builder.addStatement("return ($T) $L.getResultStream()", methodReturn.getTypeName(), queryVariableName);
 					} else if (queryMethod.isPageQuery()) {
@@ -800,6 +811,10 @@ public CodeBlock build() {
 			return builder.build();
 		}
 
+		private static boolean isStreamable(MethodReturn methodReturn) {
+			return methodReturn.toClass().equals(Streamable.class);
+		}
+
 		public static boolean returnsModifying(Class<?> returnType) {
 
 			return returnType == int.class || returnType == long.class || returnType == Integer.class

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

@@ -75,6 +75,7 @@
 import org.springframework.data.jpa.repository.sample.UserRepository;
 import org.springframework.data.jpa.repository.sample.UserRepository.NameOnly;
 import org.springframework.data.jpa.util.DisabledOnHibernate;
+import org.springframework.data.util.Streamable;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit.jupiter.SpringExtension;
 import org.springframework.transaction.annotation.Transactional;
@@ -2147,6 +2148,15 @@ void supportsJava8StreamForPageableMethod() {
 		}
 	}
 
+	@Test // GH-4070
+	void supportsStreamableForPageableMethod() {
+
+		flushTestUsers();
+
+		Streamable<User> users = repository.readStreamableAllByFirstnameNotNull(PageRequest.of(0, 2));
+		assertThat(users).hasSize(2);
+	}
+
 	@Test // DATAJPA-218
 	void findAllByExample() {
 

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

@@ -39,6 +39,7 @@
 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.util.Streamable;
 import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -199,6 +200,13 @@ void testDerivedFinderReturningListWithPageable() {
 		assertThat(users).extracting(User::getEmailAddress).containsExactly("han@smuggler.net", "kylo@new-empire.com");
 	}
 
+	@Test // GH-3830
+	void testDerivedQueryMethodReturningStreamable() {
+
+		Streamable<User> users = fragment.findStreamableByLastnameStartingWith("S");
+		assertThat(users).extracting(User::getEmailAddress).hasSize(4).contains("han@smuggler.net", "kylo@new-empire.com");
+	}
+
 	@Test // GH-3830
 	void testDerivedFinderReturningPage() {
 
@@ -526,13 +534,22 @@ void testDerivedDeleteSingle() {
 		assertThat(yodaShouldBeGone).isNull();
 	}
 
+	@Test // GH-3830
+	void shouldReturnStreamableDelete() {
+
+		Streamable<User> users = fragment.deleteStreamableByEmailAddress("yoda@jedi.org");
+
+		assertThat(users).hasSize(1);
+	}
+
 	@Test // GH-3830
 	void shouldOmitAnnotatedDeleteReturningDomainType() {
 
 		assertThatException().isThrownBy(() -> fragment.deleteAnnotatedQueryByEmailAddress("foo"))
 				.withRootCauseInstanceOf(NoSuchMethodException.class);
 	}
 
+
 	@Test // GH-3830
 	void shouldApplyModifying() {
 

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

@@ -36,6 +36,7 @@
 import org.springframework.data.jpa.repository.query.Procedure;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.query.Param;
+import org.springframework.data.util.Streamable;
 
 /**
  * @author Christoph Strobl
@@ -67,6 +68,8 @@ interface UserRepository extends CrudRepository<User, Integer> {
 
 	List<User> findByLastnameStartingWith(String lastname, Pageable page);
 
+	Streamable<User> findStreamableByLastnameStartingWith(String lastname);
+
 	Page<User> findPageOfUsersByLastnameStartingWith(String lastname, Pageable page);
 
 	Slice<User> findSliceOfUserByLastnameStartingWith(String lastname, Pageable page);
@@ -195,6 +198,8 @@ List<User> findWithParameterNameByLastnameStartingWithOrLastnameEndingWith(@Para
 
 	User deleteByEmailAddress(String username);
 
+	Streamable<User> deleteStreamableByEmailAddress(String username);
+
 	// cannot generate delete and return a domain object
 	@Modifying
 	@Query("delete from User u where u.emailAddress = ?1")

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

@@ -53,6 +53,7 @@
 import org.springframework.data.querydsl.ListQuerydslPredicateExecutor;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.query.Param;
+import org.springframework.data.util.Streamable;
 import org.springframework.transaction.annotation.Transactional;
 
 import com.querydsl.core.types.Predicate;
@@ -533,6 +534,8 @@ List<User> findUsersByFirstnameForSpELExpressionWithParameterIndexOnlyWithEntity
 	@Query("select u from User u")
 	Stream<User> streamAllPaged(Pageable pageable);
 
+	Streamable<User> readStreamableAllByFirstnameNotNull(Pageable pageable);
+
 	// DATAJPA-830
 	List<User> findByLastnameNotContaining(String part);