如何使 Jpql 查询在 Spring Jpa 存储库中使用可选返回？

Question

我在我的 JpaRepository 中使用 Jpql 查询。 问题是每次我调用带有可选返回的方法时，都会收到此错误：

java.lang.ClassCastException：class [Ljava.lang.Object； cannot be cast to class com.netpos.pagvendas.campaignuser.entity.CampaignUser ([Ljava.lang.Object; is in module java.base of loader 'bootstrap'; com.netpos.pagvendas.campaignuser.entity.CampaignUser is in unnamed加载器模块 org.springframework.boot.devtools.restart.classloader.RestartClassLoader @1c069e07)

这是我的存储库 class，我尝试使用的方法是：

findByCampaignCodUniqueCampaignAndCodTenant(String codUniqueCampaign, String codTenant)

@Repository
public interface CampaignUserRepository extends JpaRepository<CampaignUser, CampaignUserPk> {

    @Query("SELECT campaignUser, campaignUser.campaign from CampaignUser campaignUser " +
            "where campaignUser.codTenant = :codTenant " +
            "and campaignUser.flgFinished = false " +
            "and :now >= campaignUser.campaign.datStart and :now <= campaignUser.campaign.datEnd " +
            "order by campaignUser.datCreation ASC")
    List<CampaignUser> findActiveCampaign(String codTenant, ZonedDateTime now);

    @Query("SELECT campaignUser, campaignUser.campaign from CampaignUser campaignUser " +
            "where campaignUser.idtCampaign = :idtCampaign ")
    List<CampaignUser> findByIdtCampaign(long idtCampaign);

    @Query("SELECT campaignUser, campaignUser.campaign from CampaignUser campaignUser " +
            "where campaignUser.campaign.codUniqueCampaign = :codUniqueCampaign " +
            "and campaignUser.codTenant = :codTenant")
    Optional<CampaignUser> findByCampaignCodUniqueCampaignAndCodTenant(String codUniqueCampaign, String codTenant);
}

是否可以在 JpaRepository 中将 Optional 与 Jpql 查询一起使用？

Answer 1

为什么选择中有两个对象？ 要通过单个查询加载CampaignUser和Campaign ，您必须以这种方式启动查询

select campaignUser from CampaignUser campaignUser join fetch campaignUser.campaign campaign

甚至

from CampaignUser campaignUser join fetch campaignUser.campaign campaign

 @Query("SELECT campaignUser from CampaignUser campaignUser join fetch campaignUser.campaign campaign " +
                "where campaign.codUniqueCampaign = :codUniqueCampaign " +
                "and campaignUser.codTenant = :codTenant")
 Optional<CampaignUser> findByCampaignCodUniqueCampaignAndCodTenant(String codUniqueCampaign, String codTenant);