hi,

I am new to hibernate. After some reading and practise, I have got a basice understanding of hibernate and currently develeping a little application use it. However, I encounter a problem and don't know how to deal with it.

In my application, there is a table A(id,...) and B(id,...),and a many to many jointable C(a_id,b_id). This is quite simple, and the code fragment is something as following:

@Entity
@Table(name = "A")
public class Item extends BaseObject {
private Long id;

private Set<B> bs = new HashSet<B>();

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
public Long getId() {
return id;
}

...

@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(name = "C", joinColumns = { @JoinColumn(name = "A_id") }, inverseJoinColumns = @JoinColumn(name = "B_id"))
public Set<B> getBs() {
return bs;
}

...
}

Now, I need to add a new column to table C, which produce C(a_id,b_id,Commments).

Since C is a join table, there are no class definiton for it in my application, what should I do?

I think this is a common scene in many applicaton, so there must be some ways to achieve this in hibernate.

Any suggestion is appreciated and thanks in advance.

You will need to define the relation as an entity itself. After that you can assign fields to the association. Take a look at this post http://forum.hibernate.org/viewtopic.php?t=981882&highlight=


Somewhere in the middle I did a little test that does something similar to this. That should answer your question.


Farzad-[/url]

Yes, I'm trying a new plan, use 2 1tomany associatians: A->C, B->C. That seems fit into my need, and I can have a POJO mapped to C now.

:-)