在实体中两次使用嵌入式ID类型

Question

In my spring-boot project, I have a custom type for ID field of my entity. I can use the type with the help of @Embeddable and @EmbeddedId .

But when I want to add another field with the same type into a single entity, I get a column mapping exception as follows:

Caused by: org.hibernate.MappingException: Repeated column in mapping for entity: 
com.example.demo.CarEntity column: id (should be mapped with insert="false" update="false")

CarId class:

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Embeddable
public class CarId implements Serializable {
    private String id;

    @Override
    public String toString() {
        return id;
    }
}

CarEntity class:

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Entity
public class CarEntity {

    @EmbeddedId
    private CarId id;

    private String name;

    private CarId anotherId;

}

Repository class:

@Repository
public interface CarRepository extends JpaRepository<CarEntity, CarId> {
}

application class:

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

    @Bean
    CommandLineRunner runner(CarRepository repository) {
        return args -> {
            CarId carId = new CarId(UUID.randomUUID().toString());
            String carName = "a car";
            CarEntity carEntity = new CarEntity(carId, carName, carId);
            repository.save(carEntity);
            repository.findAll().forEach(carEntity1 -> {System.out.println(carEntity1.getId());});
        };
    }
}

How can I add multiple fields with the same type into the entry class?

Answer 1

The solution I found is to override the field name on anotherId as follows:

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Entity
public class CarEntity {

    @EmbeddedId
    private CarId id;

    private String name;

    @Embedded
    @AttributeOverride(name="id", column = @Column(name = "anotherId"))
    private CarId anotherId;

}