why I loose the relation one-to-many with a commit ?

fedfil · **Posted:** Tue Jul 05, 2005 7:48 am

Hi all,

Hibernate version: 3.0
Name and version of the database you are using: MySQL 4.1.12
Connector: mysql-connector-java-3.0.14.jar

I have a relation one-to-many (one: team, many: players).
when I add a new player to a team, I have no error : I can find the player added with team.getPlayers();
But when I force to commit, I loose the relation between the player and the team.

Thanks for any help.

Team.hbm.xml :

Code:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping SYSTEM
      "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping package="com.rte_france.etso.proto.model">
<class name="Team" table="TEAM" lazy="true">
   <id name="id" column="TEAM_ID">
      <generator class="native">         
      </generator>
   </id>
   <property name="name" column="TEAM_NAME"></property>
   <bag name="players" cascade="persist,save-update" inverse="true" lazy="true">
      <key column="TEAM_ID"></key>
      <one-to-many class="Player"></one-to-many>
   </bag>      
</class>   
</hibernate-mapping>

Team.java

Code:

public class Team implements Serializable {
    private Long id;
    private String name;
    private Collection players = new ArrayList();

    /**
     * 
     * @param p
     */
    public void addPlayer(Player p) {
      if (p == null)
         throw new IllegalArgumentException("Can't add a null Player.");
        this.getPlayers().add(p); 
    }
    [...]
}

To add a new Player

Code:

            Player player = new Player();
            player.setName("foo");
            team.addPlayer(player);
            teamDao.makePersistent(team);

TeamDao implementation for Hibernate

Code:

public class TeamDaoHibernate implements TeamDao {
  public void makePersistent(Team team) throws InfrastructureException {
      try {
          HibernateUtil.getSession().saveOrUpdate(team);
          HibernateUtil.commitTransaction();          
      } catch (HibernateException ex) {
          throw new InfrastructureException(ex);
      }
    }

The generated SQL (show_sql=true):
Insert:

Quote:

Hibernate: insert into PERSON (PLAYER_BIRTHDAY, PERSON_NAME, PERSON_HEIGHT, PERSON_WEIGHT, PLAYER_NUMBER, TEAM_ID, PERSON_TYPE) values (?, ?, ?, ?, ?, ?, 'PLAYER');

Select:

Quote:

Hibernate: select team0_.TEAM_ID as TEAM1_, team0_.TEAM_NAME as TEAM2_1_, team0_.TEAM_WON as TEAM3_1_, team0_.TEAM_LOST as TEAM4_1_, team0_.TEAM_PLAYED as TEAM5_1_, team0_.COACH_ID as COACH6_1_ from TEAM team0_
Hibernate: select players0_.TEAM_ID as TEAM8_1_, players0_.PLAYER_ID as PLAYER1_1_, players0_.PLAYER_ID as PLAYER1_0_, players0_.PLAYER_BIRTHDAY as PLAYER3_0_0_, players0_.PERSON_NAME as PERSON4_0_0_, players0_.PERSON_HEIGHT as PERSON5_0_0_, players0_.PERSON_WEIGHT as PERSON6_0_0_, players0_.PLAYER_NUMBER as PLAYER7_0_0_, players0_.TEAM_ID as TEAM8_0_0_ from PERSON players0_ where players0_.TEAM_ID=?

Result in database

Code:

+-----------+-------------+-----------------+-------------+---------------+---------------+---------------+---------+
| PLAYER_ID | PERSON_TYPE | PLAYER_BIRTHDAY | PERSON_NAME | PERSON_HEIGHT | PERSON_WEIGHT | PLAYER_NUMBER | TEAM_ID |
+-----------+-------------+-----------------+-------------+---------------+---------------+---------------+---------+
|         4 | PLAYER      | NULL            | foo         |            98 |            78 |          NULL |    NULL |
+-----------+-------------+-----------------+-------------+---------------+---------------+---------------+---------+

christian · **Posted:** Tue Jul 05, 2005 8:12 am

Follow the tutorial in the Hibernate reference documentation, chapter 2.

fedfil · **Posted:** Tue Jul 05, 2005 9:15 am

christian wrote:

Follow the tutorial in the Hibernate reference documentation, chapter 2.

I Christian,
So, I follow the tutorial ;
I modify the method to add a player and the dao ;
I have the same error.

To add a player :

Code:

            Player player = new Player();
            player.setName("foo");
            teamDao.addPlayer(player, 5);
            return mapping.findForward("reload");

TeamDao implementation for Hibernate

Code:

        Session session = HibernateUtil.currentSession();
        Transaction tx = session.beginTransaction();
        Team team = (Team) session.load(Team.class, teamId);
        team.addPlayer(player);
        tx.commit();
        HibernateUtil.closeSession();   

Thanks for any help.

christian · **Posted:** Tue Jul 05, 2005 9:23 am

There are no players or teams in the tutorial. The whole point is to follow it step by step, if you are unable to isolate your issue. Replicating your error doesn't make much sense.

fedfil · **Posted:** Wed Jul 06, 2005 5:21 am

christian wrote:

There are no players or teams in the tutorial. The whole point is to follow it step by step, if you are unable to isolate your issue. Replicating your error doesn't make much sense.

I Christian,
I find my error : I haven't understood the inverse="true" uses!!

New Team.java

Code:

public class Team implements Serializable {
    private Long id;
    private String name;
    private Collection players = new ArrayList();

    /**
     *
     * @param p
     */
    public void addPlayer(Player p) {
      if (p == null)
         throw new IllegalArgumentException("Can't add a null Player.");
        this.getPlayers().add(p);
        p.setTeam(this);
    }
    [...]
}

Thank You for your help.