POST POST新实体时如何在Spring Data REST中引用具有继承的实体？ [英] How to reference an entity with inheritance in Spring Data REST when POSTing new entity?

问题描述

我有加入继承的实体：

支持者

@Entity
@Inheritance(strategy=InheritanceType.JOINED)
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "supporterType")
@JsonSubTypes({
    @JsonSubTypes.Type(value = PersonSupporterEntity.class, name = "PERSON"),
    @JsonSubTypes.Type(value = CompanySupporterEntity.class, name = "COMPANY")
})
@DiscriminatorColumn(name="supporter_type")
@Table(name = "supporter")
public class SupporterEntity extends UpdatableEntity {
    private long id;
    private SupporterType supporterType;
    private PartnerEntity partner;
...
}

PersonSupporter

PersonSupporter

@Entity
@DiscriminatorValue("PERSON")
@Table(name = "person_supporter")
public class PersonSupporterEntity extends SupporterEntity {
...
}

CompanySupporter

CompanySupporter

@Entity
@DiscriminatorValue("COMPANY")
@Table(name = "company_supporter")
public class CompanySupporterEntity extends SupporterEntity {
...
}

我有另一个引用SupporterEntity的实体

I have another entity which references SupporterEntity

@Entity
@Table(name = "contact")
public class ContactEntity extends UpdatableEntity {

    private long id;
    private SupporterEntity supporter;
...
    @ManyToOne // same error with @OneToOne
    @JoinColumn(name = "supporter_id", referencedColumnName = "id", nullable = false)
    public SupporterEntity getSupporter() {
        return supporter;
    }
...
}

存储库

@Transactional
@RepositoryRestResource(collectionResourceRel = "supporters", path = "supporters")
public interface SupporterEntityRepository extends JpaRepository<SupporterEntity, Long> {

    @Transactional(readOnly = true)
    @RestResource(path = "by-partner", rel = "by-partner")
    public Page<SupporterEntity> findByPartnerName(@Param("name") String name, Pageable pageable);
}

@Transactional
@RepositoryRestResource(collectionResourceRel = "person_supporters", path = "person_supporters")
public interface PersonSupporterEntityRepository extends JpaRepository<PersonSupporterEntity, Long> {

}

@Transactional
@RepositoryRestResource(collectionResourceRel = "company_supporters", path = "company_supporters")
public interface CompanySupporterEntityRepository extends JpaRepository<CompanySupporterEntity, Long> {

}

@Transactional
@RepositoryRestResource(collectionResourceRel = "contacts", path = "contacts")
public interface ContactEntityRepository extends JpaRepository<ContactEntity, Long> {

    @Transactional(readOnly = true)
    @RestResource(path = "by-supporter", rel = "by-supporter")
    public ContactEntity findBySupporterId(@Param("id") Long id);
}

我使用Spring Boot，Spring Data REST，Spring Data JPA，Hibernate，Jackson 。当我尝试使用这样的帖子请求创建一个新的ContactEntity时：

I use Spring Boot, Spring Data REST, Spring Data JPA, Hibernate, Jackson. When I try to create a new ContactEntity with a post request like this:

{
   "supporter":"/supporters/52",
   "postcode":"1111",
   "city":"Test City 1",
   "address":"Test Address 1",
   "email":"[e-mail]",
   "newsletter":true
}

我得到了这个例外：

Caused by: com.fasterxml.jackson.databind.JsonMappingException: Unexpected token (VALUE_STRING), expected FIELD_NAME: missing property 'supporterType' that is to contain type id  (for class com.facer.domain.supporter.SupporterEntity)
 at [Source: HttpInputOverHTTP@4321c221; line: 1, column: 2] (through reference chain: com.facer.domain.supporter.ContactEntity["supporter"])
at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:148) ~[jackson-databind-2.4.4.jar:2.4.4]

2天后调试我发现了一种方法，但我猜对了。所以，如果我这样发布：

After 2 days of debugging I found a way, but I kinda guessed it. So if I post it like this:

{
   "supporter":{
      "supporterType":"PERSON",
      "id":"52"
   },
   "postcode":"1111",
   "city":"Test City 1",
   "address":"Test Address 1",
   "email":"[e-mail]",
   "newsletter":true
}

它有效，但我不知道为什么。其他请求有什么问题？当引用的实体没有继承时，它就像其他地方一样。

It works, but I don't know why. What's wrong with the other request? It works like that everywhere else when the referenced entity does not have inheritance.

推荐答案

使用 RelProvider ：

1. 不要使用 @JsonTypeInfo



2. 为 SupporterEntity 子类创建 RelProvider

@Component
@Order(Ordered.HIGHEST_PRECEDENCE)
public class SupporterEntityRelProvider implements RelProvider {

  @Override
  public String getCollectionResourceRelFor(final Class<?> type) {
    return "supporters";
  }

  @Override
  public String getItemResourceRelFor(final Class<?> type) {
    return "supporter";
  }

  @Override
  public boolean supports(final Class<?> delimiter) {
    return org.apache.commons.lang3.ClassUtils.isAssignable(delimiter, SupporterEntity.class);
  }
}

另见：

• https://jira.spring.io/browse/DATAREST-344


• http://docs.spring.io/spring-hateoas/docs/current/reference/html/#configuration.at-启用

• https://jira.spring.io/browse/DATAREST-344
• http://docs.spring.io/spring-hateoas/docs/current/reference/html/#configuration.at-enable

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