[Java] Mapstruct 타입이 다른 필드 매핑하기

Mapstruct를 통해 객체 매핑 작업을 할 때 필드명은 같지만 타입이 다를 때 타입변환이 자동으로 되는데

String -> int 필드로 변환할 때는 주의해야한다.

@NoArgsConstructor
@AllArgsConstructor
@Data
@SuperBuilder
public class WishListDto {
    private Integer index;
    private String title;
    private String category;
    private String address;
    private String roadAddress;
    private String homePageLink;
    private String imageLink;
    private boolean isVisit;
    private int visitCount;
    private LocalDateTime lastVisitDate;
    private String sameFieldName;	//타입은 다르고 변수명은 동일한 필드
}

@NoArgsConstructor
@AllArgsConstructor
@Data
@Entity
@Table(name = "WishList")
@SequenceGenerator(name="RES_SEQ_GEN", sequenceName = "RES_SEQ", initialValue = 1, allocationSize = 1)
public class WishListEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "RES_SEQ_GEN")
    private Integer index;

    private String title;
    private String category;
    private String address;
    private String roadAddress;
    private String homePageLink;
    private String imageLink;
    private boolean isVisit;
    private int visitCount;
    @UpdateTimestamp
    private LocalDateTime lastVisitDate;
    private int sameFieldName;	//타입은 다르고 변수명은 동일한 필드
}

Mapper Interface

@Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE)
public interface WishListMapper extends EntityMapper<WishListDto, WishListEntity> {
    WishListMapper INSTANCE = Mappers.getMapper(WishListMapper.class);

    WishListDto toDto(WishListEntity wishListEntity);

    WishListEntity toEntity(WishListDto wishListDto);
}

Compile된 Mapper 구현체

public class WishListMapperImpl implements WishListMapper {

    @Override
    public WishListDto toDto(WishListEntity wishListEntity) {
        if ( wishListEntity == null ) {
            return null;
        }

        WishListDto.WishListDtoBuilder<?, ?> wishListDto = WishListDto.builder();

        wishListDto.index( wishListEntity.getIndex() );
        wishListDto.title( wishListEntity.getTitle() );
        wishListDto.category( wishListEntity.getCategory() );
        wishListDto.address( wishListEntity.getAddress() );
        wishListDto.roadAddress( wishListEntity.getRoadAddress() );
        wishListDto.homePageLink( wishListEntity.getHomePageLink() );
        wishListDto.imageLink( wishListEntity.getImageLink() );
        wishListDto.visitCount( wishListEntity.getVisitCount() );
        wishListDto.lastVisitDate( wishListEntity.getLastVisitDate() );
        wishListDto.sameFieldName( String.valueOf( wishListEntity.getSameFieldName() ) );		//필드 타입이 다를 때 형변환

        return wishListDto.build();
    }

    @Override
    public WishListEntity toEntity(WishListDto wishListDto) {
        if ( wishListDto == null ) {
            return null;
        }

        WishListEntity wishListEntity = new WishListEntity();

        wishListEntity.setIndex( wishListDto.getIndex() );
        wishListEntity.setTitle( wishListDto.getTitle() );
        wishListEntity.setCategory( wishListDto.getCategory() );
        wishListEntity.setAddress( wishListDto.getAddress() );
        wishListEntity.setRoadAddress( wishListDto.getRoadAddress() );
        wishListEntity.setHomePageLink( wishListDto.getHomePageLink() );
        wishListEntity.setImageLink( wishListDto.getImageLink() );
        wishListEntity.setVisit( wishListDto.isVisit() );
        wishListEntity.setVisitCount( wishListDto.getVisitCount() );
        wishListEntity.setLastVisitDate( wishListDto.getLastVisitDate() );
        if ( wishListDto.getSameFieldName() != null ) {
            wishListEntity.setSameFieldName( Integer.parseInt( wishListDto.getSameFieldName() ) );		//필드 타입이 다를 때 형변환
        }

        return wishListEntity;
    }
}

String 변수를 null 체크는 하지만 "" 공란일 때는 체크하지 않고 Integer.parseInt()를 타게 되면 NumberFormatException 발생된다.

class WishListDtoTest {

    @Test
    void testMapToDto_whenStringFieldIsNotEmpty() {
        WishListDto dto = WishListDto.builder()
                .index(1)
                .title("title")
                .address("address")
                .sameFieldName("0") // String 필드에 "0"
                .build();
        WishListEntity entity = WishListMapper.INSTANCE.toEntity(dto);

        assertThat(entity.getSameFieldName()).isEqualTo(0);
    }

    @Test
    void testMapToDto_whenStringFieldIsNull() {
        WishListDto dto = WishListDto.builder()
                .index(1)
                .title("title")
                .address("address")
                .sameFieldName(null) // String 필드에 null
                .build();

        WishListEntity entity = WishListMapper.INSTANCE.toEntity(dto);

        assertThat(entity.getSameFieldName()).isEqualTo(0);
    }

    @Test
    void testMapToDto_whenStringFieldIsEmpty() {
        WishListDto dto = WishListDto.builder()
                .index(1)
                .title("title")
                .address("address")
                .sameFieldName("") // String 필드에 공란
                .build();

        assertThatThrownBy(() -> {
            WishListEntity entity = WishListMapper.INSTANCE.toEntity(dto);      //Mapstruct 객체 매핑 시 NumberFormatException
        }).isInstanceOf(NumberFormatException.class);
    }

}

Mapstruct mapper interface에서 String -> int 형변환을 qualifiedByName을 사용해 명시적으로 선언

@Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE)
public interface WishListMapper extends EntityMapper<WishListDto, WishListEntity> {
    WishListMapper INSTANCE = Mappers.getMapper(WishListMapper.class);

    WishListDto toDto(WishListEntity wishListEntity);

    @Mapping(target = "sameFieldName", source = "sameFieldName", qualifiedByName = "mapToInteger")
    WishListEntity toEntity(WishListDto wishListDto);

    @Named("mapToInteger")
    default int mapToInteger(String str) {
        if (str == null || str.isEmpty()) {
            return 0;
        }
        return Integer.parseInt(str);
    }
}

Compile된 Mapper 구현체

public class WishListMapperImpl implements WishListMapper {

    @Override
    public WishListDto toDto(WishListEntity wishListEntity) {
        if ( wishListEntity == null ) {
            return null;
        }

        WishListDto.WishListDtoBuilder<?, ?> wishListDto = WishListDto.builder();

        wishListDto.index( wishListEntity.getIndex() );
        wishListDto.title( wishListEntity.getTitle() );
        wishListDto.category( wishListEntity.getCategory() );
        wishListDto.address( wishListEntity.getAddress() );
        wishListDto.roadAddress( wishListEntity.getRoadAddress() );
        wishListDto.homePageLink( wishListEntity.getHomePageLink() );
        wishListDto.imageLink( wishListEntity.getImageLink() );
        wishListDto.visitCount( wishListEntity.getVisitCount() );
        wishListDto.lastVisitDate( wishListEntity.getLastVisitDate() );
        wishListDto.sameFieldName( String.valueOf( wishListEntity.getSameFieldName() ) );

        return wishListDto.build();
    }

    @Override
    public WishListEntity toEntity(WishListDto wishListDto) {
        if ( wishListDto == null ) {
            return null;
        }

        WishListEntity wishListEntity = new WishListEntity();

        wishListEntity.setSameFieldName( mapToInteger( wishListDto.getSameFieldName() ) );
        wishListEntity.setIndex( wishListDto.getIndex() );
        wishListEntity.setTitle( wishListDto.getTitle() );
        wishListEntity.setCategory( wishListDto.getCategory() );
        wishListEntity.setAddress( wishListDto.getAddress() );
        wishListEntity.setRoadAddress( wishListDto.getRoadAddress() );
        wishListEntity.setHomePageLink( wishListDto.getHomePageLink() );
        wishListEntity.setImageLink( wishListDto.getImageLink() );
        wishListEntity.setVisit( wishListDto.isVisit() );
        wishListEntity.setVisitCount( wishListDto.getVisitCount() );
        wishListEntity.setLastVisitDate( wishListDto.getLastVisitDate() );

        return wishListEntity;
    }
}

 "" 공란일 때도 0으로 정상 변환

@Test
void testMapToDto_whenStringFieldIsEmpty() {
    WishListDto dto = WishListDto.builder()
            .index(1)
            .title("title")
            .address("address")
            .sameFieldName("") // String 필드에 공란
            .build();
    WishListEntity entity = WishListMapper.INSTANCE.toEntity(dto);
    
    assertThat(entity.getSameFieldName()).isEqualTo(0);
}

 

 

https://mapstruct.org/documentation/stable/reference/html/#selection-based-on-qualifiers

MapStruct 1.5.5.Final Reference Guide