Question

I am using HIbernate 3.2.5. I have a one-to-many association between Dept and Training table. One dept is capable of taking more than one training.

<id name="deptId" type="integer" column="DEPT_ID">
      <generator class="assigned"></generator>
  </id>
  <property name="deptName">
      <column name="DEPT_NAME"></column>
  </property>
  <map name="trainingDetails" inverse="false" cascade="delete" lazy="false">
      <key column="DEPT_ID"></key>
      <map-key formula="ID" type="integer"></map-key>
      <one-to-many class="model.Training"/>
  </map>      

When I try to delete an entry:

SessionFactory sf = new Configuration().configure("trial.cfg.xml").buildSessionFactory();
    Session session = sf.openSession();
    Dept department = new Dept();
    department.setDeptId(2);        
    session.delete(department);
    session.flush();
    session.close();

I can see that for the child table an update query is getting printed in the console rather than a delete query:

update training set DEPT_ID=null where DEPT_ID=?

But since the cascade is delete hence the child table should also execute a delete operation rather than an update right?

Please let me know where is my mistake.

Regards,

Answer 1

It will do if you use cascade as DELETE_ORPHAN stating that child object can’t exist standalone.

In addition, you are not loading the object graph before deleting. Perform delete as below:

SessionFactory sf = new Configuration().configure("trial.cfg.xml")
                                       .buildSessionFactory();
    Session session = sf.openSession();
    //load the object before deleting
    Dept department = session.get(Dept.class, new Integer(2));
    session.delete(department);
    session.flush();
    session.close();