Hibernate version: 3:0
Name and version of the database you are using:PostgreSql 8


Hi.

I have class Person with a Set friends which is unidirectional many-to-many
to Person.

class Person {
...
/**
* @hibernate.set
* table="FRIENDS_OF_PERSONS"
* lazy="true"
* cascade="none"
* @hibernate.collection-key
* column="HAVE_A_FRIEND"
* @hibernate.collection-many-to-many
* class="com.polatach.model.Person"
* column="IS_A_FRIEND"
*/
public Set getFriends() {
return friends;
}
...
}

Hibernate makes new tabl, FRIENDS_OF_PERSONS

create table FRIENDS_OF_PERSONS (
HAVE_A_FRIEND int8 not null,
IS_A_FRIEND int8 not null,
primary key (HAVE_A_FRIEND, IS_A_FRIEND)
)
alter table FRIENDS_OF_PERSONS add constraint FK6E3EBDA854972751 foreign key (HAVE_A_FRIEND) references PERSONS

alter table FRIENDS_OF_PERSONS add constraint FK6E3EBDA836CBE45C foreign key (IS_A_FRIEND) references PERSONS



I have a problem with session.delete(person).
When I want to delete a Person who have friends in Set friends (in table FRIENDS_OF_PERSONS he appears in HAVE_A_FRIEND column) there is no problem:
Hibernate: delete from FRIENDS_OF_PERSONB where HAVE_A_FRIEND=?
Hibernate: delete from PERSONS where PERSONS_ID=?

But when i want to delete a person who is a friend(in table FRIENDS_OF_PERSONS he appears in IS_A_FRIEND column, there is an error from database:

13:50:44,500? WARN JDBCExceptionReporter:57 - SQL Error: 0, SQLState: null

13:50:44,500? ERROR JDBCExceptionReporter:58 - Batch entry 0 delete from PERSONS where PERSONS_ID=691 was aborted. Call getNextException to see the cause.

13:50:44,500? WARN JDBCExceptionReporter:57 - SQL Error: 0, SQLState: 23503

13:50:44,500? ERROR JDBCExceptionReporter:58 - ERROR: update or delete on "persons" violates foreign key constraint "fk6e3ebda836cbe45c" on "FRIENDS_OF_PERSONS"


So my question is how to delete person object wich is a friend. And why hibernate do not generate sql:

alter table FRIENDS_OF_PERSONS add constraint FK6E3EBDA854972751 foreign key (HAVE_A_FRIEND) references PERSONS ON DELETE CASCADE

This is limitation of current implementation of Hibernate - it's working on object model level, and can't automagicaly remove any references from everywhere. You should either remove such references manualy in code, or use biderectional associations with on-delete="cascade" attribute on "key" element.

what about many-to-many associations, on-delete="cascade" doesn't seem to be allowed. i have the exact same type of associations and i can't seem to find a combination of cascades that will remove the row in the assocation table when a person is removed, but not the group as a whole.