Java 使用一对一关系时，如何修复“具有相同标识符值的不同对象已与会话关联”错误

我试图在两个实体之间创建一对一的关系：

项目实体

@Entity
@Table(name = "projects")
public class Project {

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

    @OneToOne(mappedBy = "project", cascade = CascadeType.ALL, optional = false, fetch = FetchType.LAZY)
    private CrawlerConfiguration crawlerConfiguration;

    // Getters and setters ...

    public void setCrawlerConfiguration(CrawlerConfiguration crawlerConfiguration) {
        if (crawlerConfiguration == null) {
            if (this.crawlerConfiguration != null) {
                this.crawlerConfiguration.setProject(null);
            }
        } else {
            crawlerConfiguration.setProject(this);
        }

        this.crawlerConfiguration = crawlerConfiguration;
    }

爬虫配置实体

@Entity
@Table(name = "crawler_configurations")
public class CrawlerConfiguration {

    @Id
    private Long id;

    @OneToOne(fetch = FetchType.LAZY)
    @MapsId
    private Project project;

    // Getters and setters ...
}

当用户创建新项目时，还应为该项目创建配置

@Transactional
public Project createProject(Project project) {
    project.setCrawlerConfiguration(new CrawlerConfiguration());
    return projectRepository.save(project);
}

不幸的是，它会导致以下异常：

javax.persistence.EntityExistsException:具有 相同的标识符值已与会话关联： [com.github.peterbencze.serritorcloud.model.entity.crawlerConfiguration 1]

创建实体的正确方法是什么？

试试这个

 @OneToOne(fetch = FetchType.LAZY)
 @PrimaryKeyJoinColumn
 private Project project;

---

在您的爬网配置实体中

感谢您的帮助。我尝试添加PrimaryKeyJoinColumn注释，结果出现了另一个异常：org.hibernate.id.IdentifierGenerationException:调用save之前必须手动分配此类的id:com.github.peterbencze.serritorcloud.model.entity.crawlerConfiguration抱歉，没有找到。您的爬虫配置表是否有Id列？您还应该在CrawlerConfiguration实体的Id上添加@GeneratedValuestrategy=GenerationType.IDENTITY，还可以添加@Columnname=Id、unique=true、nullable=False在添加这两个注释后，它不再引发异常。但是，它会在数据库中为配置生成2行。请从爬虫_配置中选择*；ID 1 2

@Entity
@Table(name = "crawler_configurations")
public class CrawlerConfiguration {

    @Id
    private Long id;

    @OneToOne(fetch = FetchType.LAZY)
    @MapsId
    private Project project;

    // Getters and setters ...
}