Spring Data JPA：在 save() 方法之后从实体中获取数据

Question

我在我的项目中使用 Spring Data JPA 和 Hibernate JPA 提供程序。 在我的服务中，我有一个方法，它将实体保存在数据库中，而不是使用返回的对象，我尝试获取有关该实体的更多详细信息。 因此，不会获取详细信息。在日志中我只看到插入语句，没有选择详细信息。

这是我的代码：

配置：

@Configuration
@Profile("test")
@EnableJpaRepositories(basePackages = {"pl.lodz.uml.sonda.common.repositories"})
@EnableTransactionManagement
@PropertySource(value = "classpath:db.test.properties")
public class PersistenceConfigTest {
  @Autowired
  private Environment env;
  @Value("classpath:sql/test-initialization.sql")
  private Resource sqlInitializationScript;

  @Bean
  public DataSource dataSource() {
    BasicDataSource dataSource = new BasicDataSource();

    dataSource.setDriverClassName(env.getProperty("jdbc.driverClassName"));
    dataSource.setUrl(env.getProperty("jdbc.url"));
    dataSource.setUsername(env.getProperty("jdbc.username"));
    dataSource.setPassword(env.getProperty("jdbc.password"));

    return dataSource;
  }

  @Bean
  public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
    LocalContainerEntityManagerFactoryBean entityManagerFactory = new LocalContainerEntityManagerFactoryBean();
    HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();

    adapter.setShowSql(env.getProperty("hibernate.showSQL", Boolean.class));
    adapter.setGenerateDdl(env.getProperty("hibernate.hbm2ddl", Boolean.class));

    entityManagerFactory.setDataSource(dataSource());
    entityManagerFactory.setPackagesToScan("pl.lodz.uml.sonda.common.domains");
    entityManagerFactory.setJpaVendorAdapter(adapter);

    Properties properties = new Properties();
    properties.put("hibernate.hbm2ddl.auto", env.getProperty("hibernate.hbm2ddl.auto"));

    entityManagerFactory.setJpaProperties(properties);

    return entityManagerFactory;
  }

  @Bean(name = "transactionManager")
  public PlatformTransactionManager platformTransactionManager() {
    EntityManagerFactory entityManagerFactory = entityManagerFactory().getObject();
    return new JpaTransactionManager(entityManagerFactory);
  }

  @Bean
  public DataSourceInitializer dataSourceInitializer() {
    ResourceDatabasePopulator populator = new ResourceDatabasePopulator();
    populator.addScript(sqlInitializationScript);

    DataSourceInitializer initializer = new DataSourceInitializer();
    initializer.setDataSource(dataSource());
    initializer.setDatabasePopulator(populator);
    initializer.setEnabled(env.getProperty("db.initialization", Boolean.class));

    return initializer;
  }

  @Bean
  public ProbeService probeService() {
    return new ProbeServiceImpl();
  }
}

服务：

@Service
@Transactional
public class ProbeServiceImpl implements ProbeService {
  @Autowired
  private ProbeRepository probeRepository;

  @Override
  public Probe saveProbe(Probe probe) {
    Probe saved = probeRepository.save(probe);
    saved.getGroup().getName();

    return saved;
  }
}

简单测试：

@RunWith(SpringJUnit4ClassRunner.class)
@ActiveProfiles("test")
@ContextConfiguration(classes = {PersistenceConfigTest.class})
@Transactional
@TransactionConfiguration(defaultRollback = true)
@TestExecutionListeners({
  DependencyInjectionTestExecutionListener.class,
  DirtiesContextTestExecutionListener.class,
  TransactionalTestExecutionListener.class
})
public class ProbeServiceImplTest {
  @Autowired
  private ProbeService probeService;

  @Test
  public void test() {
    Probe probe = ProbeFixtures.generateProbeSample("Test one");
    probe.setGroup(ProbeFixtures.generateProbeGroupSample(1));

    Probe saved = probeService.saveProbe(probe);
    System.out.println("Group name: " + saved.getGroup().getName());
  }
}

实体：

@Entity
@Table(name = "probes")
public class Probe {
  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  @Column(name = "probe_id")
  private long probeId;

  @Column(name = "probe_title", nullable = false)
  private String title;

  @Column(name = "probe_description", nullable = true)
  private String description;

  @ManyToOne(fetch = FetchType.EAGER)
  @JoinColumn(name = "probe_group_id", nullable = true)
  private ProbeGroup group;

  @OneToOne(fetch = FetchType.EAGER)
  @JoinColumn(name = "probe_image_id", nullable = true)
  private ProbeFile image;

  @Column(name = "probe_published_date", nullable = false)
  private Date published;

  @Column(name = "probe_last_updated_date", nullable = false)
  private Date updated;

  @Column(name = "probe_expire_date", nullable = false)
  private Date expires;

  @Column(name = "probe_is_active", nullable = false)
  private boolean isActive;

  @OneToMany(mappedBy = "probe", fetch = FetchType.LAZY)
  private List<Question> questions;

  @OneToMany(mappedBy = "probe", fetch = FetchType.LAZY)
  private List<Vote> votes;

  public Probe() {
    questions = new LinkedList<>();
    votes = new LinkedList<>();
  }
  // getters & setters ...


@Entity
@Table(name = "probe_groups")
public class ProbeGroup {
  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  @Column(name = "probe_group_id")
  private long probeGroupId;

  @Column(name = "probe_group_name", nullable = false, unique = true)
  private String name;

  @Column(name = "probe_group_description", nullable = true)
  private String description;

  @OneToMany(mappedBy = "group", fetch = FetchType.LAZY)
  private List<Probe> probes;

  public ProbeGroup() {
    probes = new LinkedList<>();
  }
  // getters & setters ...

最后几行日志：

Hibernate: insert into probes (probe_description, probe_expire_date, probe_group_id, probe_image_id, probe_is_active, probe_published_date, probe_title, probe_last_updated_date) values (?, ?, ?, ?, ?, ?, ?, ?)
Group name: null

我也尝试过在save()之后运行spring data jpa方法-getOne(id)，但是还是不行（insert statement调用，select not）；

更新： 我从我的服务和测试中删除了@Transactional 注释。现在，当我保存一个实体然后获取同一个实体时，我在日志中有两个 sql 语句：插入然后选择。 也许我的问题是因为错误的持久性/事务配置。你怎么看？

Answer 1

这可能有点过时了，但我遇到了同样的问题，发现问题是休眠二级缓存。

Answer 2

save() 方法可能会也可能不会立即将您的更改写入数据库。如果要立即提交更改，则需要使用T saveAndFlush(T entity) 方法。

Answer 3

打印语句返回 null，因为只有 getName() 返回 null。 这意味着您的数据正在被保存，并且对象被返回。如果“保存”的对象为空，它应该抛出一个空指针异常。