Spring DATA JPA with Java 8 Stream NonUniqueResultException

Question

I defined a repository based on PagingAndSortingRepository to have the below query implementation

@Query(" SELECT me FROM CustomerModelEntity me WHERE  me.planNum = :planNum AND me.customerModelStatusCode IN ('AVL','PHO')" +
        " AND me.modelCode IN (SELECT e.modelCode FROM ModelEntity e WHERE e.modelStatusCode IN ('AVL','PHO'))")
Stream<CustomerModelEntity> findByPlanNum(@Param("planNum") String planNum);

The result is expected to have multiple results. But, the result came out to be an exception as below

Caused by: javax.persistence.NonUniqueResultException: result returns more than one elements
    at org.hibernate.jpa.internal.QueryImpl.getSingleResult(QueryImpl.java:505) [hibernate-entitymanager-4.3.7.Final.jar:4.3.7.Final]
    at org.springframework.data.jpa.repository.query.JpaQueryExecution$SingleEntityExecution.doExecute(JpaQueryExecution.java:202) [spring-data-jpa-1.7.2.RELEASE.jar:]
    at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:74) [spring-data-jpa-1.7.2.RELEASE.jar:]
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:97) [spring-data-jpa-1.7.2.RELEASE.jar:]
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:88) [spring-data-jpa-1.7.2.RELEASE.jar:]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:395) [spring-data-commons-1.9.2.RELEASE.jar:]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:373) [spring-data-commons-1.9.2.RELEASE.jar:]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) [spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$DefaultMethodInvokingMethodInterceptor.invoke(RepositoryFactorySupport.java:486) [spring-data-commons-1.9.2.RELEASE.jar:]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) [spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99) [spring-tx-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281) [spring-tx-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) [spring-tx-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) [spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136) [spring-tx-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    ... 125 more

The same @Query implementation works good if I have List instead of a Stream

@Query(" SELECT me FROM CustomerModelEntity me WHERE  me.planNum = :planNum AND me.customerModelStatusCode IN ('AVL','PHO')" +
        " AND me.modelCode IN (SELECT e.modelCode FROM ModelEntity e WHERE e.modelStatusCode IN ('AVL','PHO'))")
List<CustomerModelEntity> findByPlanNum(@Param("planNum") String planNum);

Is it safe to assume that Java 8 support is not complete in Spring Data JPA/ am I doing something wrong here?

Answer 1

As per Spring data JPA documentation:

Not all Spring Data modules currently support Stream as a return type.

Try changing the PagingAndSortingRepository -> JpaRepository and see if it works.

Update:

I debugged it further and found out that Spring Data JPA 1.8.0 supports Streaming, if you are using some other version then upgrade to 1.8.0. I was getting the same exception on 1.7.2