@Id in sleep mode
I have code
@Entity
@Table(name = "USER")
public class User {
@Id
@Column(name = "id", nullable = false, unique = true)
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
When I try to add a user to the table, I catch
org.h2.jdbc.JdbcSQLException: NULL not allowed for column "ID"; SQL statement:
insert into USER (id, birthday, email, first_name, last_name, login, password, id_role) values (null, ?, ?, ?, ?, ?, ?, ?) [23502-181]
This is my code for adding user to db
stock2.setBirthday(new Date(46));
stock2.setEmail("sss");
stock2.setFirstName("oleg");
stock2.setId(506l);
stock2.setLastName("gubov");
stock2.setLogin("OP");
stock2.setPassword("1");
Role role2 = new Role();
role2.setName("poil");
role2.setId(7l);
stock2.setRole(role2);
HibernateUserDao dao = new HibernateUserDao();
System.out.println(stock2.getId() + " -----------before");
dao.create(stock2);
and the create method code:
public void create(User user) {
Session session = null;
try {
session = HibernateUtil.getSessionFactory().openSession();
session.beginTransaction();
session.save(user);
session.getTransaction().commit();
} catch (Exception e) {
session.getTransaction().rollback();
throw e;
} finally {
if (session != null && session.isOpen()) {
session.close();
}
}
}
In my opinion, id is 7, but not NULL. And "java" thinks differently. Where could the problem be?
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You are calling dao.create()
, so you intend to insert a row into the database. Why are you using GenerationType.IDENTITY
inserting your own id
?
GenerationType.IDENTITY
means yours JPA Provider
will use the column IDENTITY
(so it id
will be assigned from the database side). Hibernate, knowing it won't post your id
in the SQL statement.
By the way, this is not the best option for creating identifiers. GenerationType.IDENTITY
has some performance issues (it doesn't support preallocation and JPA Provider
might make a query SELECT
after every inserted row, just to see what was generated id
).
To be able to insert your own values like id
, you can simply remove @GeneratedValue
(which de facto means you want it to be id
automatically generated) annotations.
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Here is a link describing your problem and suggesting possible solutions: http://en.wikibooks.org/wiki/Java_Persistence/Identity_and_Sequencing#Common_Problems_4
Excerpts:
null is inserted into the database or an insert error.
[...] You may have also left out that your primary key column in your table is an identity type.
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