I am having a problem upgrading to JBoss 4.0.5. Please see the following post on the JBoss EJB3 forum.

http://www.jboss.org/index.html?module=bb&op=viewtopic&t=97260

Any assistance would be greatly appreciated.

Hi Jason,

I don't think the null pointer exception (in fromClause.java) is caused Hibernate 3.2.0.GA that ships along with JBoss 4.0.5GA. To get it to work it will require you to manually patch the fromClause.java (very simple patch, only 1 or 2 lines). There is a bug in the Hibernate JIRA (http://opensource.atlassian.com/projects/hibernate/browse/HHH-2159), if you want it fixing (officially), please vote for the issue.

Cheers,


Andy

My real problem is the mappedBy pointing to a property that is on a superclass of my object.

I am using a joined inheritance strategy.

Is there any reason I should not be able to map a collection to property of a superclass? This worked fine in 4.0.4.

if the superclass is an @Entity or a @Mappedsuperclass, it should work (unless you're not explaining all the details)

I have the same issue. I resolved it by changing the parent to a MappedSuperclass and copying all columns from the parent table into each of the child tables.

When the superclass was using the joined inheiritance strategy, and I was trying to map a collection of a subclass on a parent mapped by the superclass, I got an exception that the mappedBy property didn't exist on the subclass (just as described above).

So, it seems that currently you can't have a collection of subclasses on a parent where the parent is mapped by the superclass if you're using a joined inheiritance strategy? Is this limitation intentional or a bug?

Emmanuel communicated the following to me, and I figured it made sense to post it here since it is directly relevant (hopefully he won't mind):

Personally, I naturally assumed that you could map a relationship to a subclass using mappedBy on a superclass, even if the superclass is an entity. At least that's more like the way OO inheritance behaves. I recall changing to MappedSuperclass has other effects (at least w/ pure JPA), such loss of ability to do polymorphic queries. IMHO, seems it would be better to make the decision to go with MappedSuperclass versus Entity based on that kind of concern, not how you've set up the inheritance hierarchy. I can relate to wanting to keep things consistent, it's just that it seems like it should work as a few of us expected--so it takes time to figure out why it doesn't and how to work around it.

Instead of using MappedSuperclass, I chose to leave the superclass as an entity, make the accessors in the superclass abstract, and implement them in the subclass. Seems a bit duplicative, but it works and retains the consistency Emmanuel likes.

I was a bit optimistic in my assessment that it worked. I actually ended up getting ClassCastException when Hibernate would confuse the subtypes. I wrote up more about the approaches I worked through at my blog:
http://clarkupdike.blogspot.com/2007/01/hibernate-mappedby-to-superclass.html

I have the same problem. Here's an example. Exam has many ExamDetails.


@Entity
public class Exam {

@OneToMany(mappedBy="exam")
private ExamDetails details

}


@Entity
@DiscriminatorValue("details")
public class ExamDetails extends Details {

}

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "type", discriminatorType = DiscriminatorType.STRING)
public class Details extends MasterDetails {

}



@MappedSuperclass
public class MasterDetails {

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(nullable = false)
private Exam exam;

//getters & setters

}


I get the following errir:
org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: exam


Was there a workaround for this problem, and why is it not intuitive to support this feature?

I am having the same problem, as the last poster - is this by design or by accident?