使用 MapStruct 将多个字段映射为一个

Question

我将这 3 个类放在不同的文件中

public class Book {

   @Id
    @GeneratedValue
    private Long id;

    @NonNull
    private String title;

    @NonNull
    private Author author;

}

public class Author {

    @Id
    @GeneratedValue
    private Long id;

    @NonNull
    private String firstName;

    @NonNull
    private String lastName;

}

public class BookDTO {

    private Long id;

    @NonNull
    private String title;

    @NonNull
    private String author;

}

我有以下映射器

@Mapper
public interface BookMapper { 

    BookMapper INSTANCE = Mappers.getMapper(BookMapper.class);

    @Mappings({
            @Mapping(source = "author.lastName", target = "author")
    })
    BookDTO toDTO(Book book);

}

这目前只映射lastName和works，我想用

映射Book中的作者字符串

author.firstName + " " + author.lastName

我怎么能这样做？我无法在 MapStruct 文档中找到任何内容。

Answer 1

MapSruct 不支持将多个源属性映射到单个目标属性。

您有两种方法可以实现这一目标：

使用映射#表达式

@Mapping( target = "author", expression = "java(book.getAuthor().getFirstName() + \" \" + book.getAuthor().getLastName())")

使用@AfterMapping 或@BeforeMapping

@Mapper
public interface BookMapper { 

    BookMapper INSTANCE = Mappers.getMapper(BookMapper.class);


    @Mapping(target = "author", ignore = true)
    BookDTO toDTO(Book book);

    @AfterMapping
    default void setBookAuthor(@MappingTarget BookDTO bookDTO, Book book) {
        Author author = book.getAuthor();
        bookDTO.setAuthor(author.getFirstName() + " " + author.getLastName());
    }

}