Jpa合并抛出StaleObjectStateException？

Question

有代码，当我试图创建四个客户时。1.将Customer3 1，2写入数据库；2.合并Customer3(具有相同的id，例如1)；3. merget Customer4(再次使用相同的id )--我想创建相同实体的任何版本

所以,

public static void main(String[] args) {
        EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("Info");
        EntityManager entityManager = entityManagerFactory.createEntityManager();

        Customer customer1 = new Customer("1", "Vladislav");
        Customer customer2 = new Customer("2", "Maria");
        Customer customer3 = new Customer("1", "Ekaterina");
        Customer customer4 = new Customer("1", "Helen");

        entityManager.getTransaction().begin();
        entityManager.persist(customer1);
        entityManager.persist(customer2);
        entityManager.getTransaction().commit();

        entityManager.getTransaction().begin();
        entityManager.merge(customer3);
        entityManager.getTransaction().commit();

        entityManager.getTransaction().begin();
        entityManager.merge(customer4);
        entityManager.getTransaction().commit();

        //get versions here:
        entityManager = entityManagerFactory.createEntityManager();
        AuditReader auditReader = AuditReaderFactory.get(entityManager);
        List<Number> versions = auditReader.getRevisions(Customer.class, "1");
        System.out.println("========");
        System.out.println(Arrays.toString(versions.toArray()));

        entityManager.close();
        entityManagerFactory.close();
    }

客户实体：

package entity;

import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import org.hibernate.envers.Audited;

import javax.persistence.*;


@Getter
@Setter
@NoArgsConstructor
@Entity
@Audited
public class Customer {
    @Id
    @Column(length = 100, nullable = false)
    private String id;
    private String name;

    @Version
    int version;

    public Customer(String id, String name) {
        this.id = id;
        this.name = name;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", version=" + version +
                '}';
    }
}

当我坚持只有客户1,2和合并客户3-一切都好。

但是我在customer4实体中添加了mergin -有错误消息occours -

线程"main“javax.persistence.OptimisticLockException: Row中的异常被另一个事务更新或删除(或未保存的值映射不正确)：由: org.hibernate.StaleObjectStateException: Row引起的entity.Customer#1被另一个事务更新或删除(或未保存-值映射不正确)：entity.Customer#1 .

为什么我任何时候都不能合并？

Answer 1

您只能将客户与具有最新版本的实例合并。

customer1有version=0

id = '1‘的当前版本现在是0

customer3有version=0，因此合并是可能的，并在合并version=1之后进行。

id = '1‘的当前版本现在是1

customer4有version=0，因此不再可能合并。