org.hibernate.LazyInitializationException in spring data jpa

Question

I met 'org.hibernate.LazyInitializationException: could not initialize proxy - no Session' in spring data jpa.

Below is my code.

    // this is service layer
    @Transactional(rollbackFor = Exception.class)
    public BlogEntity saveBlog(BlogEntity blogEntityInput) {
        BlogEntity blogEntity = blogDao.find(blogEntityInput.getId());
        System.out.println(blogEntity);
        return blogDao.saveBlog(blogEntityInput);
    }

   // this is dao layer which will call
   @Override
   public BlogEntity find(Integer id) {
    return blogRepository.getOne(id); // JpaRepository#getOne
   }

The exception will occur when I print the blogEntity after I call getOne. I know that getOne is lazy loaded. But I have already add the @Transactional which will ensure the inner method will be in a hibernate session. How could the LazyInitializationException still occur?

Thanks.

Below is my full database related spring code.

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
  entityManagerFactoryRef = "h2_entityManagerFactory",
  basePackages = { "com.taobao.rest.repository.h2" },
        transactionManagerRef = "h2_manager"

)
public class H2DBConfig {

  @Primary
  @Bean(name = "h2_dataSource")
  public DataSource dataSource(){
      DriverManagerDataSource dataSource = new DriverManagerDataSource();
      dataSource.setDriverClassName("org.h2.Driver");
      dataSource.setUrl("jdbc:h2:~/new-taobao");
      dataSource.setUsername("taobao");
      dataSource.setPassword("");

      return dataSource;
  }

  @Primary
  @Bean(name = "h2_entityManagerFactory")
  public LocalContainerEntityManagerFactoryBean h2EntityManagerFactory() {
      LocalContainerEntityManagerFactoryBean em
              = new LocalContainerEntityManagerFactoryBean();
      em.setDataSource(dataSource());
      em.setPackagesToScan(new String[] { "com.taobao.rest.entity.h2" });
      em.setPersistenceUnitName("h2_unit");
      JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
      em.setJpaVendorAdapter(vendorAdapter);
      em.setJpaProperties(additionalProperties());

      return em;
  }

  Properties additionalProperties() {
        Properties properties = new Properties();
        properties.setProperty("hibernate.hbm2ddl.auto", "update");
        properties.setProperty(
                "hibernate.dialect", "org.hibernate.dialect.H2Dialect");
        properties.setProperty("hibernate.show_sql", "true");
        return properties;
    }


    @Bean(name = "h2_manager")
    public PlatformTransactionManager transactionManager(
            @Qualifier("h2_entityManagerFactory") EntityManagerFactory emf){
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(emf);
        return transactionManager;
    }
}