Lombok @Builder 사용 시 MapStruct @AfterMapping 동작 이슈

MappingTarget

@Getter
@ToString(exclude = "orders")
@Table(name = "members")
@Entity
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@DynamicUpdate
public class Member {

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private Long id;
	private String name;
	private Integer age;
	
	@Enumerated(EnumType.STRING)
	private Gender gender;
	
	@Setter
	private String email;
	
	@Column(name = "phone_number")
	private String phoneNumber;
	
	@Column(name = "join_at")
	private LocalDateTime joinAt;
	
	@OneToMany(mappedBy = "member", fetch = FetchType.LAZY)
	private List<Order> orders = new ArrayList<>();
	
	@PrePersist
	private void onJoinAt() {
		this.joinAt = LocalDateTime.now();
	}
	
	@Builder
	public Member(Long id, String name, Integer age, Gender gender, String email, String phoneNumber) {
		this.id = id;
		this.name = name;
		this.age = age;
		this.gender = gender;
		this.email = email;
		this.phoneNumber = phoneNumber;
	}

 

Source

import lombok.Data;

@Data
public class MemberRequest {

	private String name;
	private Integer age;
	private String gender;
	private String email;
	private String phoneNumber;
}

 

Mapper

import org.mapstruct.AfterMapping;
import org.mapstruct.Mapper;
import org.mapstruct.MappingTarget;
import org.mapstruct.ReportingPolicy;
import org.mapstruct.factory.Mappers;

import com.ahn.jpa.dto.MemberRequest;
import com.ahn.jpa.model.Member;

@Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE)
public interface MemberMapper {

	MemberMapper MAPPER = Mappers.getMapper(MemberMapper.class);
	
	Member mapToModel(MemberRequest request);
	
	@AfterMapping
	default void add(MemberRequest request, @MappingTarget Member member) {
		member.setEmail("야호");
	}
}

 

Mapper 구현체

import com.ahn.jpa.dto.MemberRequest;
import com.ahn.jpa.model.Member;
import com.ahn.jpa.model.enums.Gender;
import javax.annotation.Generated;

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2024-03-15T15:51:10+0900",
    comments = "version: 1.5.3.Final, compiler: Eclipse JDT (IDE) 1.4.50.v20210914-1429, environment: Java 17.0.1 (Eclipse Adoptium)"
)
public class MemberMapperImpl implements MemberMapper {

    @Override
    public Member mapToModel(MemberRequest request) {
        if ( request == null ) {
            return null;
        }

        Member.MemberBuilder member = Member.builder();

        member.age( request.getAge() );
        member.email( request.getEmail() );
        if ( request.getGender() != null ) {
            member.gender( Enum.valueOf( Gender.class, request.getGender() ) );
        }
        member.name( request.getName() );
        member.phoneNumber( request.getPhoneNumber() );

        return member.build();
    }
}

 

위와 같이 @AfterMapping을 설정하였지만 실제 구현된 코드에는 "add()" 메소드가 추가되어 있지 않다.

Builder를 사용할 경우엔 @TargetMapping에 실제 맵핑할 대상이 아닌 대상의 Builder를 추가해줘야 한다.

공식 문서에도 기재되어 있는 내용으로 보인다.
https://mapstruct.org/documentation/stable/reference/html/#customizing-mappings-with-before-and-after

MapStruct 1.5.5.Final Reference Guide

Important: when using a builder, the @AfterMapping annotated method must have the builder as @MappingTarget annotated parameter so that the method is able to modify the object going to be build. The build method is called when the @AfterMapping annotated method scope finishes. MapStruct will not call the @AfterMapping annotated method if the real target is used as @MappingTarget annotated parameter.

문서 내용 적용하여 변경된 코드

import org.mapstruct.AfterMapping;
import org.mapstruct.Mapper;
import org.mapstruct.MappingTarget;
import org.mapstruct.ReportingPolicy;
import org.mapstruct.factory.Mappers;

import com.ahn.jpa.dto.MemberRequest;
import com.ahn.jpa.model.Member;

@Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE)
public interface MemberMapper {

	MemberMapper MAPPER = Mappers.getMapper(MemberMapper.class);
	
	Member mapToModel(MemberRequest request);
	
	@AfterMapping
	default void add(MemberRequest request, @MappingTarget Member.MemberBuilder member) {
		member.email("야호");
	}
}

 

변경된 구현체

import com.ahn.jpa.dto.MemberRequest;
import com.ahn.jpa.model.Member;
import com.ahn.jpa.model.enums.Gender;
import javax.annotation.Generated;

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2024-03-15T16:03:36+0900",
    comments = "version: 1.5.3.Final, compiler: Eclipse JDT (IDE) 1.4.50.v20210914-1429, environment: Java 17.0.1 (Eclipse Adoptium)"
)
public class MemberMapperImpl implements MemberMapper {

    @Override
    public Member mapToModel(MemberRequest request) {
        if ( request == null ) {
            return null;
        }

        Member.MemberBuilder member = Member.builder();

        member.age( request.getAge() );
        member.email( request.getEmail() );
        if ( request.getGender() != null ) {
            member.gender( Enum.valueOf( Gender.class, request.getGender() ) );
        }
        member.name( request.getName() );
        member.phoneNumber( request.getPhoneNumber() );

        add( request, member );

        return member.build();
    }
}