如何在 MapStruct 中映射扩展类

Question

Gotta question regarding mapStruct. I have case where I extend class from base entity and not sure how to map it. Here is my case.

BaseEntity:

public class BaseEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @Column(name = "id")
    private Long id;
}

BaseDto:

public class BaseDto {

    private Long id;
}

UserEntity:

public class User extends BaseEntity {
    private String name;
    private String lastName;
    private String username;
    private String password;
    private String profilePicturePath;
}

UserDto:

public class UserDto extends BaseDto {
    private String name;
    private String lastName;
    private String username;
    private String password;
    private String profilePicturePath;
}

And mapper is like this:

@Mapper(uses = {BaseMapper.class})
public interface UserMapper {

    User userDtoToUser(UserDto userDto);

    UserDto userToUserDto(User user);
}

BaseMapper:

@Mapper
public interface BaseMapper {

    BaseEntity dtoToEntity(BaseDto baseDto);

    BaseDto entityToDto(BaseEntity baseEntity);
}

Problem is that I don't get ID property mapped.

Thank you for your time.

EDIT:

There is no error shown, in mapper implementation (generated code) there is no mapping for that ID:

 @Override
    public User userDtoToUser(UserDto userDto) {
        if ( userDto == null ) {
            return null;
        }

        UserBuilder user = User.builder();

        user.name( userDto.getName() );
        user.lastName( userDto.getLastName() );
        user.username( userDto.getUsername() );
        user.password( userDto.getPassword() );
        user.profilePicturePath( userDto.getProfilePicturePath() );

        return user.build();
    }

Answer 1

I'm guessing (as you have not put buider code) the problem is that your builder class does not include parent class field. MapStruct makes some assumption while generating code for mapper. From documentation -

The default implementation of the BuilderProvider assumes the following:

1. The type has a parameterless public static builder creation method that returns a builder. So for example Person has a public static method that returns PersonBuilder.
2. The builder type has a parameterless public method (build method) that returns the type being build In our example PersonBuilder has a method returning Person.
3. In case there are multiple build methods, MapStruct will look for a method called build, if such method exists then this would be used, otherwise a compilation error would be created.

If you are using Lombok, you can solve this by using @SuperBuilder as -

@SuperBuilder
@Getter
@ToString
public class UserDto extends BaseDto {
  private String name;
  private String lastName;
  private String username;
  private String password;
  private String profilePicturePath;
}

@Getter
@SuperBuilder
class BaseDto {
  private Long id;
}

@SuperBuilder
@Getter
@ToString
public class User extends BaseEntity {
  private String name;
  private String lastName;
  private String username;
  private String password;
  private String profilePicturePath;
}

@Setter
@Getter
@SuperBuilder
class BaseEntity {
  private Long id;
}

And generated could looks like -

@Override
public User userDtoToUser(UserDto userDto) {
    if ( userDto == null ) {
        return null;
    }

    UserBuilder<?, ?> user = User.builder();

    user.id( userDto.getId() );
    user.name( userDto.getName() );
    user.lastName( userDto.getLastName() );
    user.username( userDto.getUsername() );
    user.password( userDto.getPassword() );
    user.profilePicturePath( userDto.getProfilePicturePath() );

    return user.build();
}