利用Mapstruct映射双向关系对象
利用Mapstruct映射双向关系对象
提问于 2019-04-12 15:51:58
我想知道Mapstruct是否以及如何帮助映射具有双向关系的对象(在我的例子中是一对多)：
public class A{
private Set<B> listB;
}
public class B{
private A a;
}从实体映射/映射到实体会生成StackOverflowError。(我预计这会发生)。另一方面，封闭的Mapstruct问题469和1163似乎暗示mapstruct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
但这是行不通的。无论是否应用"CycleAvoidingMappingContext“，堆栈溢出错误都保持不变。
那么如何使用循环和利用mapstruct来映射对象呢？(我希望避免完全手动映射)
回答 2
Stack Overflow用户
发布于 2019-04-14 14:47:46
为了使映射正常工作，您可以尝试使用以下映射程序：
@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);
}如果不存在从Set<B>映射到Set<B>的方法，则不会映射A中的集合。
Stack Overflow用户
发布于 2019-04-16 15:59:20
同时，我找到了一个解决方案:首先忽略有问题的字段，并将其映射到"AfterMapping“中。在我的例子中，我还想独立地映射子对象。在我的例子中，@Context只包含一个Boolean (boolean不工作)，它告诉我进入循环的位置(startedFromPru pru是父进程)：
父级映射器(包含一组许可证)：
@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);
}
}
}子级映射器：
@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));
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/55646904
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