Hibernate 尝试为 OneToOne 实体关系外键插入 null答案

【问题标题】：Hibernate attempts to insert null for the OneToOne entity relationship foreign keyHibernate 尝试为 OneToOne 实体关系外键插入 null
【发布时间】：2017-09-14 09:20:24
【问题描述】：

这是我用于 oneToOne 映射的 SpringBoot Jpa 实现。当我保存时，Hibernate 尝试在company_details 表中为company_id 外键插入null，如下面的CompanyService.createCompany() 代码所示。感谢任何帮助。

CREATE TABLE companies (
  id                  BIGSERIAL PRIMARY KEY    NOT NULL,
  access_token        VARCHAR(255)             NOT NULL,
  access_secret       VARCHAR(255)             NOT NULL,
  token_expires_at    TIMESTAMP WITH TIME ZONE NOT NULL
);

CREATE TABLE company_details (
  id                   BIGSERIAL PRIMARY KEY    NOT NULL,
  company_id           BIGSERIAL                NOT NULL REFERENCES companies (id),
  company_name         VARCHAR(50)              NOT NULL
);

@Entity
@Table(name = "companies")
public class Company {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(updatable = false)
    private Long id;

    @OneToOne(
        fetch = FetchType.EAGER,
        mappedBy = "company",
        cascade = CascadeType.ALL
    )
    private CompanyDetails details;
    ...
}

@Entity
@Table(name = "company_details")
public class CompanyDetails {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @OneToOne
    @JoinColumn(name = "company_id")
    @MapsId
    @JsonBackReference // avoid cyclic references
    private Company company;

    @Size(max = 50)
    @NotNull
    private String companyName;
}

@Service
public class CompanyService {
    @Autowired
    private CompanyRepository companyRepository;

    @Transactional
    public Company createCompany() {
        CompanyDetails cd = new CompanyDetails();
        cd.setName("cd");

        Company c = new Company();
        c.setDetails(cd);
        this.companyRepository.save(c);
    }
}

【问题讨论】：

标签： hibernate jpa spring-boot spring-data

【解决方案1】：

您的实体似乎没有共享主键。

因此删除@MapsId 并保持如下：

@OneToOne
@JoinColumn(name = "company_id")
@JsonBackReference // avoid cyclic references
private Company company;

同时在 companyDetails 中设置公司：

    CompanyDetails cd = new CompanyDetails();
    cd.setName("cd");

    Company c = new Company();
    c.setDetails(cd);

    cd.setCompany(c);

    this.companyRepository.save(c);

【讨论】：

感谢您的帮助。