Persistence: adding to a Collection

[justinb]

Hi

I have an Entity called "Course" (as in a training course), it looks basically like so:

@Entity
@Table(name = "training_course")
public class Course implements Serializable {
...
 private Collection<Course> prerequisites;
...
 @ManyToMany(fetch = LAZY)
 @JoinTable(
 table = @Table(name = "training_course_req"),
 joinColumns = { @JoinColumn(name = "course") },
 inverseJoinColumns = { @JoinColumn(name = "prerequisite") })
 public Collection<Course> getPrerequisites() {
 return prerequisites;
 }

 public void setPrerequisites(Collection<Course> prerequisites) {
 this.prerequisites = prerequisites;
 }
...
}

Now I want to have a Stateless that adds and removes from this Collection
like so...

@TransactionAttribute(TransactionAttributeType.REQUIRED)
@RolesAllowed( { BasicRoles.SUPERUSER, Roles.TRAINING_MANAGER })
public boolean addPrerequisite(String courseCode, String preCode) {
 log.debug("Adding Prerequisite " + preCode + " to " + courseCode);
 boolean success = false;
 Course course = entities.find(Course.class, courseCode);
 if (course != null) {
 log.debug("The course is " + course.getName());
 Course prerequisite = entities.find(Course.class, preCode);
 if (prerequisite != null) {
 log.debug("The prerequisite is " + prerequisite.getName());
 success = course.getPrerequisites().add(prerequisite);
 entities.merge(course);
 log.debug("Add was " + (success ? "successful" : " unsuccessful"));
 } else
 log.debug("Prerequisite is null");
 } else
 log.debug("Course is null!");
 return success;
}

According to the logs, all the code executes correctly, but when I look at the table, nothing has happened!

What am I doing wrong???

Thanks,
Justin

[justinb]

Sorry, I am running EJB-RC2 on JBoss 4.0.3-RC2

[xiangya]

ha,
I guess that maybe you could focus 3 aspects:
1,db connect url, least possible
2,transaction, least possoible
3,entity bean in collection best need equals and hashcode method override, maybe?

Regards.
xiangya

[justinb]

Thanks Xianga,

I don't think it's the DB because everything else works fine (and I get no errors), and I have similar transaction attributes on other similar methods, and they work 100%.

I will try overriding hashCode()

Thanks a lot.
Justin