Hi to all,
I'm developing my first EJB3 application with eclipse. I don't know i manage the insert into a database in case of duplicate key.
I use this code:
Table KGTWANAUSER01:
-user (key)
-password
Entity bean:
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity @Table(name="KGTWANAUSER01")
public class User implements Serializable {
private static final long serialVersionUID = 1L;
@Id @Column(name="USER") private String USER;
@Column(name="PASSWORD") private String PASSWORD;
public User(String us, String pswd)
{ this.user=us; this.password=pswd; }
public String getUSER()
{ return USER; }
public String getPASSWORD()
{ return PASSWORD; }
public void setUSER(String uSER)
{ USER = uSER; }
public void setPASSWORD(String pASSWORD)
{ PASSWORD = pASSWORD; }
}
#
Stateless Session Bean (register method):
....
public String register(String user, String password)
{
User us = new User (user, password)
List existing = em.createQuery(
"select username from User where username = #{user.username}")
.getResultList();
if (existing.size()==0)
{
em.persist(us);
return "OK";
#
}
else
{
return "NO;"
}
}
....
My problem is this:
I have two client A e B that want to create their new user, both with the username "ale":
A call register method, execute the select, no other user "ale" are register so existing.size=0;
B call the same method, and also in this case no other user "ale" are register so existing.size=0;
A make em.persist(us) adn the transaction is OK
B try to make the insert with the persist, but the user now exist, so the application crashs and Jboss show me a list of errors caused by the duplicate key...
Ho i can solve this problem?
Thanks to All
Alessandro