Question

可以帮我解决将对象保存到PostgreSQL数据库的问题吗？我使用序列ID和注释@SequenceGenerator无法从序列中获取一些id，已经自动创建了。（序列）序列是＆＃34; user_id_user_sec＆＃34;。我可以保存一个实体，但是第二次抛出异常：

ERROR:   ERROR: duplicate key value violates unique constraint "user_pkey"
  Detail: Key (id_user)=(0) already exists.
Info:   HHH000010: On release of batch it still contained JDBC statements
Severe:   org.hibernate.exception.ConstraintViolationException: could not execute  statement
    at      org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelega te.java:129)

我的实体，我可以保存到数据库：

@Entity
@Table(name = "\"User\"")
public class User implements java.io.Serializable {

   @Id
   @GeneratedValue(strategy = GenerationType.SEQUENCE, generator="seq")
   @SequenceGenerator(name="seq", sequenceName="user_id_user_seq", allocationSize=1)
   private int idUser;
   @Column
   private String apiKey;
   @Column
   private String email;
   @Column
   private String name;
   @Column
   private String password;
   @Column
   private boolean isAdmin;
   @Column
   private boolean enabled;
   private Set deviceWatchedByUsers = new HashSet(0);

和getter and setter以及我的UserDAO方法，女巫保存这个实体是：

public static Integer addUser(User u){
  Session session = HibernateUtil.getSessionFactory().openSession();
  Transaction tx = null;
  Integer userId = null;
  try{
     tx = session.beginTransaction();
     User user = u;

     userId = (Integer) session.save(user); 
     tx.commit();
  }catch (HibernateException e) {
     if (tx!=null) tx.rollback();
     e.printStackTrace(); 
  }finally {
     session.close(); 
  }
  return userId;

}

创建数据库的脚本是：

CREATE TABLE "user"
(
  id_user serial NOT NULL,
  api_key character varying(255),
  email character varying(255) NOT NULL,
  name character varying(255) NOT NULL,
  password character varying(255) NOT NULL,
  is_admin boolean NOT NULL,
  enabled boolean NOT NULL,
  CONSTRAINT user_pkey PRIMARY KEY (id_user),
  CONSTRAINT user_email_key UNIQUE (email)
)
WITH (
  OIDS=FALSE
);
ALTER TABLE "user"
  OWNER TO postgres;

Answer 1

您需要将DB表id_user更改为：

id_user bigint NOT NULL

您不需要串行类型，因为它是Hibernate使用序列调用分配id列。

如果您想让数据库负责分配ID，那么SEQUENCE生成器只会与数据库ID生成策略竞争。

在这种情况下，您需要"select" generator代替。

Hibernate + PostgreSQL +串口PK（ID） - 无法将对象保存到DB

1 个答案: