无法为 X 类创建自链接.未找到持久实体

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问题描述

使用 Spring Data REST 时出现标题错误.如何解决?

Getting the error in the title when using Spring Data REST. How to resolve?

Party.java:

@Entity
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@JsonTypeInfo(use=JsonTypeInfo.Id.CLASS, property="@class")
@JsonSubTypes({ @JsonSubTypes.Type(value=Individual.class, name="Individual") })
public abstract class Party {
  @Id
  @GeneratedValue(strategy=GenerationType.IDENTITY)
  protected Long id;

  protected String name;

  @Override
  public String toString() {
    return id + " " + name;
  }

  ...getters, setters...
}

Individual.java:

@Entity
public class Individual extends Party {

  private String gender;

  @Override
  public String toString() {
    return gender + " " + super.toString();
  }

  ...getters, setters...
}

PartyRepository.java:

public interface PartyRepository extends JpaRepository<Party,Long> {
}

如果我发布，它会正确保存到数据库:

If I POST, it saves to the db correctly:

POST /parties {"@class":"com.example.Individual", "name":"Neil", "gender":"MALE"}

但返回 400 错误:

But returns a 400 error:

{"cause":null,"message":"Cannot create self link for class com.example.Individual! No persistent entity found!"}

从存储库中检索后看起来它是个人:

It looks like it's an Individual after retrieving from repository:

System.out.println(partyRepository.findOne(1L));
//output is MALE 1 Neil

看起来 Jackson 可以确定它是一个人:

Looks like Jackson can figure out that it's an individual:

System.out.println( new ObjectMapper().writeValueAsString( partyRepository.findOne(1L) ) );
//output is {"@class":"com.example.Individual", "id":1, "name":"Neil", "gender":"MALE"}

为什么 SDR 想不通?

Why can SDR not figure it out?

如何解决?最好使用 XML 配置.

How to fix? Preferably with XML config.

版本:
SDR 2.2.0.RELEASE
SD JPA 1.7.0.RELEASE
休眠 4.3.6.Final

Versions:
SDR 2.2.0.RELEASE
SD JPA 1.7.0.RELEASE
Hibernate 4.3.6.Final

推荐答案

SDR 存储库需要一个非抽象实体，在您的情况下它将是个人.您可以在 google 或此处搜索有关 SDR 为何需要非抽象实体的解释.

SDR repositories expect a non-abstract entity, in your case it would be Individual. You can google or search here for explaination on why SDR expects a non-abstract entity.

您看到该错误是因为 SDR 在构建链接时找不到引用个人的存储库.只需添加单个存储库而不导出它就可以解决您的问题.

You are seeing that error since SDR could not find a repository refering Individual while constructing links. Simply adding Individual respository and not exporting it would solve your problem.

@RepositoryRestResource(exported = false)
public interface IndividualRepository extends JpaRepository<Individual,Long> {
}

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