✅ 값 타입 컬렉션

• 값 타입을 하나 이상 저장할 때 사용
• @ElementCollection, @CollectionTable 사용
• 데이터베이스는 컬렉션을 같은 테이블에 저장할 수 없다.
• 컬렉션을 저장하기 위한 별도의 테이블이 필요함

@Entity
public class Member extends BaseEntity{

    @Id @GeneratedValue
    @Column(name = "MEMBER_ID")
    private Long id;
    @Column(name = "USERNAME")
    private String username;

    @Embedded
    private Address homeAddress;

    **@ElementCollection
    @CollectionTable(name = "FAVORITE_FOOD", joinColumns =
        @JoinColumn(name = "MEMBER_ID")
    )
    @Column(name = "FOOD_NAME")
    private Set<String> favoriteFoods = new HashSet<>();

    @ElementCollection
    @CollectionTable(name = "ADDRESS", joinColumns =
        @JoinColumn(name = "MEMBER_ID")
    )
    private List<Address> addressHisotry = new ArrayList<>();**
}

@Embeddable
public class Address {
    private String city;
    private String street;
    private String zipcode;

    public Address() {
    }

    public Address(String city, String street, String zipcode) {
        this.city = city;
        this.street = street;
        this.zipcode = zipcode;
    }

		@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Address address = (Address) o;
        return Objects.equals(city, address.city) &&
                Objects.equals(street, address.street) &&
                Objects.equals(zipcode, address.zipcode);
    }

    @Override
    public int hashCode() {
        return Objects.hash(city, street, zipcode);
    }
}

✅ 값 타입 컬렉션 사용

• 값 타입 저장 예제

→ member만 persist해도 값 타입 컬렉션들도 자동으로 삽입됨 (본인 스스로의 라이프 사이클 없기 때문 → member에 소속되어 있음)

Member member = new Member();
member.setUsername("member1");
member.setHomeAddress(new Address("homeCity", "street", "10000"));

member.getFavoriteFoods().add("치킨");
member.getFavoriteFoods().add("족발");
member.getFavoriteFoods().add("피자");

member.getAddressHisotry().add(new Address("old1", "street", "10000"));
member.getAddressHisotry().add(new Address("old2", "street", "10000"));

em.persist(member);

tx.commit();