I have the following tables (in pseudocode):

CREATE TABLE FOO (
id int primary key,
name varchar(50)
)

CREATE TABLE GROUP (
id int primary key,
name varchar(50)
)

CREATE TABLE FOO_GROUP (
id int primary key,
foo_id int foreign key references FOO(id),
group_id int foreign key references GROUP(id),
order_index int
)

Note the "order_index" column in FOO_GROUP. This will show up later. I have the following objects (also in pseudocode):

@Entity
public class Foo {
... basic persisted bean ...
}

@Entity
public class Group {
...basic persisted stuff...

@ManyToMany
@JoinTable(...name, joinColumns, inverseJoinColumns...)
private List<Foo> foosInGroup;
}

Basically, if the FOO_GROUP table didn't have the "order_index" column, I'd be fine. However, I need the "foosInGroup" List in Group to be ordered based on the "order_index" field.

Is this possible? If so, how?

Thanks in advance!

Hi,

one way of doing this is to create an intermediate entity which you use to create a link between Foo and Group. This type of mapping was just recently discussed here http://forum.hibernate.org/viewtopic.php?t=987912.

One you have such an intermediate entity say FooGroupLink you should be able to use the @OrderBy annotation on your foosInGroup property:



Another alternative would be to use to map the joint table ot a collection of components. This approach is described in "Java Persistence with Hibernate". The idea stays the same though. You need an intermediate 'entity' FooGroupLink which in this case is embeddable.

Hope this helps,
--Hardy

One more question about this situation:

Is there any way to retrieve "order_index" from Group or Foo?

This situation refers to a own attribute in the relation N:N, and I need to use retrieve it from one of the sides. ¿Can anyone help me?

I'm searching for this long time, but no answer got >_<