有没有办法使用Spring Data的CrudRepository＃save（）方法保存带有预定义@EmbeddedId值的@Entity？

Question

I'm creating a new service with the goal of consuming Kafka events in an idempotent manner and storing the data into a new PostgreSQL database.

The event will provide data which will be used in the composite key:

@Embeddable
public class MyCompositeKey implements Serializable {

    @Column(name="field1", nullable = false)
    private UUID field1;

    @Column(name="field2", nullable = false)
    private UUID field2;

    @Column(name="field3", nullable = false)
    private UUID field3;

... boilerplate Constructors/getters ...

And the Entity will be referencing it via @EmbeddedId :

@Entity
@Table
public class MyEntity implements Serializable {

  @EmbeddedId private MyCompositeKey myCompositeKey;

... Columns/Constructors/getters ...

When an event is consumed, I want to let spring-data-jpa be smart enough to know whether we are replacing data from an existing MyEntity, or creating a new row.

The logic was deemed safe enough to use the CrudRepository#save method before researching the expectation of the logic within that method:

    @Transactional
    public <S extends T> S save(S entity) {
        if (this.entityInformation.isNew(entity)) {
            this.em.persist(entity);
            return entity;
        } else {
            return this.em.merge(entity);
        }
    }

I've gotten to the point where the transactions appear to be completed, but no records are persisted to the table.

I've confirmed via debugging that the call to #save is branching into the return this.em.merge(entity) logic referenced above.

I've only found one possibly helpful blog post[1] for a similar scenario, and am lost on where to go next after it didn't seem to resolve the issue.

The only other option I can foresee is to manually go through a potential three-query execution:

1. findById
2. if exists, delete
3. save

Components

• spring-boot-starter 2.0.6
• spring-boot-starter-data-jpa 2.0.6
• hibernate 5.2.x

References

[1] https://jivimberg.io/blog/2018/11/05/using-uuid-on-spring-data-jpa-entities/

Answer 1

Alright, I found the issue. All of this design was working fine, it was the configuration which was missing.

For some context - Spring Boot seems to configure default javax.sql.DataSource , default javax.persistence.EntityManagerFactory , and default org.springframework.transaction.PlatformTransactionManager beans.

My context was configured with a javax.sql.DataSource bean in order to specify a configuration prefix distinction using org.springframework.boot.context.properties.ConfigurationProperties .

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = {"com.myservice"})
public class RepositoryConfiguration {

  @Bean
  @ConfigurationProperties(prefix = "myservice.datasource")
  public DataSource dataSource() {
    return DataSourceBuilder.create().build();
  }
}

My context did not add in replacements for the dependent javax.persistence.EntityManagerFactory and org.springframework.transaction.PlatformTransactionManager beans.

The fix was to add in all of the configuration. From the docs :

You must create LocalContainerEntityManagerFactoryBean and not EntityManagerFactory directly, since the former also participates in exception translation mechanisms in addition to creating EntityManagerFactory.

The resulting configuration:

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = {"com.myservice"})
public class RepositoryConfiguration {

  @Bean
  @ConfigurationProperties(prefix = "myservice.datasource")
  public DataSource dataSource() {
    return DataSourceBuilder.create().build();
  }

  @Bean
  public LocalContainerEntityManagerFactoryBean entityManagerFactory() {

    HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();

    LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
    factory.setJpaVendorAdapter(vendorAdapter);
    factory.setPackagesToScan("com.myservice");
    factory.setDataSource(dataSource());
    return factory;
  }

  @Bean
  public PlatformTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
    JpaTransactionManager txManager = new JpaTransactionManager();
    txManager.setEntityManagerFactory(entityManagerFactory);
    return txManager;
  }
}