如何在 mapstruct 映射器中使用 spring 注入，存储库 class？

Question

@Data
public class FilesDTO {

    private int issue;
    private String uniqueStr;
    private StorageDomain xml;
    private StorageDomain pdf;
    private StorageDomain stop;
}
@Data
public class BackHalfDomain {
    private int articleId;
    private String uniqueStrr;
    private long xmlContentId;
    private long pdfContentId;
    private long stopId;
    private int issueNumber;
}

Using a repository class I have to fetch a StorageDomain object from the ID in BackHalfDomain . So I have to map StorageDomain object with respective fields. like StorgeDomain sd = repo.findById(id).get(); and set this sd object in FilesDTO 's xml field and so on. This is my mapper

@Mapper(componentModel = "spring")
public interface FilesDTOMapper {

    public static final FilesDTOMapper fileDTOMapper = Mappers.getMapper(FilesDTOMapper.class);

    @Mapping(target = "issue", source = "domain.issueNumber")
    @Mapping(target = "DOI", source = "domain.doi")
    public FilesDTO map(BackHalfDomain domain);

}

I have used uses but wasn't successful. I have used @Mapping(target="xyz", expression="java(repo.findById(id))")" but all I got was NullPointerException Spring injection isin't working. Can someone have a solution for this? I am just started with mapstruct

Answer 1

Since mapstruct 1.2 you can use a combination of @AfterMapping and @Context.

@Mapper(componentModel="spring")
public interface FilesDTOMapper { 

   @Mapping(target = "xyz", ignore = true)
   @Mapping(target = "issue", source = "domain.issueNumber")
   @Mapping(target = "DOI", source = "domain.doi")
   FilesDTO map( BackHalfDomain domain, @Context MyRepo repo);

   @AfterMapping
   default void map( @MappingTarget FilesDTO target, BackHalfDomain domain, @Context MyRepo repo) {
        target.setXYZ(repo.findById(domain.getId()));
   }
 }

In 1.1 you would need to transform the mapper to a abstract class

@Mapper(unmappedTargetPolicy = org.mapstruct.ReportingPolicy.IGNORE,
        componentModel = "spring",
        uses = {})
public abstract class FilesDTOMapper {

    @Autowired
    protected MyRepo repo;


    @Mapping(target = "issue", source = "domain.issueNumber")
    @Mapping(target = "DOI", source = "domain.doi")
    @Mapping(target="xyz", expression="java(repo.findById(domain.getId())))")
    public FilesDTO map(BackHalfDomain domain);

}

Answer 2

I ran into this same problem. The solution was to use a Decorator as suggested in this answer . Following your code, the solution would be something like the following.

First, we have to specifiy the Decorator in the Mapper:

@Mapper(componentModel = "spring", unmappedTargetPolicy = ReportingPolicy.IGNORE)
@Primary
@DecoratedWith(FilesDTOMapperDecorator.class)
public interface FilesDTOMapper {
      // basic mapping here
      public FilesDTO map(BackHalfDomain domain);
}

Then, implement the Decorator:

public abstract class FilesDTOMapperDecorator implements FilesDTOMapper {

    @Autowired
    @Qualifier("delegate")
    private FilesDTOMapper delegate;

    @Autowired
    private SomeRepository someRepository;

    @Override
    public FilesDTO map(BackHalfDomain domain) {
        // Delegate basic mapping
        FilesDTO filesDTO = delegate.map(domain);

        // Use the repository as needed to set additional mapping
        filesDTO.setSomeValue(repo.findById(id).getSomeValue());

        return filesDTO;
    }
}