使用Mapstruct与双向关系映射对象

Question

我想知道Mapstruct是否以及如何帮助映射具有双向关系的对象（在我的情况下是一对多）：

public class A{
     private Set<B> listB;
}

public class B{
     private A a;
}

从/向实体的映射产生StackOverflowError。 （我希望这会发生）。另一方面，封闭的Mapstruct问题469和1163似乎暗示maptruct不会直接支持它。我试过这个例子：

https://github.com/mapstruct/mapstruct-examples/tree/master/mapstruct-mapping-with-cycles

但这不起作用。无论是否应用“CycleAvoidingMappingContext”，stackoverflower都保持不变。

那么如何使用循环映射对象并利用mapstruct？ （我想避免完整的手动映射）

Answer 1

为了使映射起作用，您可以尝试使用以下映射器：

@Mapper
public interface MyMapper {

    A map(A a, @Context CycleAvoidingMappingContext context);

    Set<B> map(Set<B> b, @Context CycleAvoidingMappingContext context);

    B map(B b, @Context CycleAvoidingMappingContext context);
}

如果从Set<B>映射到Set<B>的方法不存在那么A中的集合将不会被映射。

Answer 2

与此同时，我找到了一个解决方案：首先，我忽略了有问题的字段并将其映射到“AfterMapping”中。在我的情况下，我想独立地映射孩子。在我的情况下，@Context只包含一个Boolean（boolean不工作）告诉我进入周期的地方（startedFromPru pru是父母）：

父映射器（包含许可证集）：

@Mapper(componentModel = "spring", uses = {DateTimeMapper.class, LicenseMapper.class, CompanyCodeMapper.class, ProductHierarchyMapper.class})
public abstract class ProductResponsibleUnitMapper {

    @Autowired
    private LicenseMapper licenseMapper;

    @Mappings({@Mapping(target = "licenses", ignore = true)})
    public abstract ProductResponsibleUnit fromEntity(ProductResponsibleUnitEntity entity, @Context Boolean startedFromPru);

    @Mappings({@Mapping(target = "licenses", ignore = true)})
    public abstract ProductResponsibleUnitEntity toEntity(ProductResponsibleUnit domain, @Context Boolean startedFromPru);

    @AfterMapping
    protected void mapLicenseEntities(ProductResponsibleUnit pru, @MappingTarget ProductResponsibleUnitEntity pruEntity, @Context Boolean startedFromPru){
        if(startedFromPru) {
            pruEntity.getLicenses().clear(); //probably not necessary
            pru.getLicenses().stream().map(license -> licenseMapper.toEntity(license, startedFromPru)).forEach(pruEntity::addLicense);
        }
    }

    @AfterMapping
    protected void mapLicenseEntities(ProductResponsibleUnitEntity pruEntity, @MappingTarget ProductResponsibleUnit pru, @Context Boolean startedFromPru){
        if(startedFromPru) {
            pru.getLicenses().clear(); //probably not necessary
            pruEntity.getLicenses().stream().map(licenseEntity -> licenseMapper.fromEntity(licenseEntity, startedFromPru)).forEach(pru::addLicense);
        }
    }

}

儿童映射器：

@Mapper(componentModel = "spring", uses = { DateTimeMapper.class, CompanyCodeMapper.class, ProductHierarchyMapper.class,
        CountryCodeMapper.class })
public abstract class LicenseMapper {

    @Autowired
    private ProductResponsibleUnitMapper pruMapper;

    @Mappings({ @Mapping(source = "licenseeId", target = "licensee"), @Mapping(target = "licensor", ignore = true) })
    public abstract License fromEntity(LicenseEntity entity, @Context Boolean startedFromPru);


    @Mappings({ @Mapping(source = "licensee", target = "licenseeId"), @Mapping(target = "licensor", ignore = true) })
    public abstract LicenseEntity toEntity(License domain, @Context Boolean startedFromPru);

    @AfterMapping
    protected void mapPru(LicenseEntity licenseEntity, @MappingTarget License license,
            @Context Boolean startedFromPru) {
        //only call ProductResponsibleUnitMapper if mapping did not start from PRU -> startedFromPru is false
        if (!startedFromPru) {
            license.setLicensor(pruMapper.fromEntity(licenseEntity.getLicensor(), startedFromPru));
        }
    }

    @AfterMapping
    protected void mapPru(License license, @MappingTarget LicenseEntity licenseEntity,
            @Context Boolean startedFromPru) {
        //only call ProductResponsibleUnitMapper if mapping did not start from PRU -> startedFromPru is false
        if (!startedFromPru) {
            licenseEntity.setLicensor(pruMapper.toEntity(license.getLicensor(), startedFromPru));
        }
    }