Question

我正在使用springBoot，我想将OneToMany的关系从父母映射到孩子。直接将entity与eager一起使用会获取递归记录，因此，尝试对ModelMapper使用DTO映射到Entity，但是我无法弄清楚去做吧。请假设getters和setters。

Parent.java

@Entity
public class Parent {

    @Id
    private int parentId;

    private String a;

    @OneToMany(mappedBy = "parent")
    private Set<Child> child;

Child.java

@Entity
public class Child {

    @Id
    private int childId;

    private String c;

    @ManyToOne
    @JoinColumn(name = "b")
    private Parent parent;

我有使用findAll方法的有效存储库和服务层。

ParentDto.java

public class ParentDto {

    private String a;

    private Set<Child> child;

ParentController.java

@RestController
public class ParentController {

    @Autowired
    private ModelMapper modelMapper;

    @Autowired
    private ParentService parentService;


    @RequestMapping(method = RequestMethod.GET, value="/parents" )
    public List<ParentDto> getParents() {
        List<Parent> parents =  parentService.getAll();
        return parents.stream()
                .map(x-> modelMapper.map(x, ParentDto.class))
                .collect(Collectors.toList());
    }
}

错误：：尝试获取http://localhost:8080/parents

时

.
.
ModelMapper mapping errors: 1) Converter org.modelmapper.internal.converter.CollectionConverter@51381583 failed to convert java.util.Set to java.util.Set. 1 error
org.modelmapper.MappingException: ModelMapper mapping errors:

1) Converter org.modelmapper.internal.converter.CollectionConverter@51381583 failed to convert java.util.Set to java.util.Set.

1 error
    at org.modelmapper.internal.Errors.throwMappingExceptionIfErrorsExist(Errors.java:380)
    at org.modelmapper.internal.MappingEngineImpl.map(MappingEngineImpl.java:80)
.
.

Answer 1

这与“ N + 1”和“无限递归”无关，可以在映射器中添加Conver方法；使用ModelMapper映射子级 https://amydegregorio.com/2018/10/03/mapping-children-with-modelmapper/

Answer 2

您需要在定义的父映射上使用@JsonIgnore批注在您的孩子实体中。

有关更多信息，请参阅此文档- https://fasterxml.github.io/jackson-annotations/javadoc/2.5/com/fasterxml/jackson/annotation/JsonIgnore.html

如何使用ModelMapper映射oneToMany

2 个答案: