[예제] 상속관계 매핑

1. 요구사항 추가

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• 상품의 종류는 음반, 도서, 영화가 있고 이후 더 확장이 될 수 있어
• 모든 데이터는 등록일과 수정일이 필수!

 

2. 도메인 모델

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3. 도메인 모델 상세

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4. 테이블 설계

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5. Item class

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• @Inheritance(strategy = InheritanceType.SINGLE_TABLE)
• @DiscriminatorColumn

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn
public abstract class Item {

    @Id
    @GeneratedValue() //default = auto.
    @Column(name = "ITEM_ID")
    private Long id;

Hibernate: 
    
    create table Item (
       DTYPE varchar(31) not null,
        ITEM_ID bigint not null,
        name varchar(255),
        price integer not null,
        stockQuantity integer not null,
        actor varchar(255),
        director varchar(255),
        author varchar(255),
        isbn varchar(255),
        artist varchar(255),
        etc varchar(255),
        primary key (ITEM_ID)
    )

 

6. Test

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• book 을 저장해 보자.

Book book = new Book();
book.setName("booook");
book.setAuthor("nananana");
em.persist(book);
tx.commit();

• 전략을 JOINED로 바꿔보자.

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorColumn
public abstract class Item {

Hibernate: 
    
    create table Book (
       author varchar(255),
        isbn varchar(255),
        ITEM_ID bigint not null,
        primary key (ITEM_ID)
    )

 

7. @MappedSuperclass

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• BaseEntity

@MappedSuperclass
public abstract class BaseEntity {

    private String createdBy;
    private LocalDateTime createdDate;
    private String modifiedBy;
    private String lastModifiedBy;
    private LocalDateTime lastModifiedDate;

• Item class를 상속받는 class는 BaseEntity를 별도로 상속받을 필요 없음
• Item이 BaseEntity 상속받음
• 각 테이블에 BaseEntity 속성이 추가된 것을 확인할 수 있다.

Hibernate: 
    
    create table Team (
       TEAM_ID bigint not null,
        createdBy varchar(255),
        createdDate timestamp,
        lastModifiedBy varchar(255),
        lastModifiedDate timestamp,
        modifiedBy varchar(255),
        name varchar(255),
        primary key (TEAM_ID)
    )

 

8. Github : 210811 EXAMPLE

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GitHub - bsh6463/JPA_EXAMPLE