many-to-many inverse=true and delete

mpopetz · **Joined:** Tue Oct 28, 2003 12:09 pm **Posts:** 46

I have a many-to-many bidirectional mapping and am deleting an object from the inverse=true side of the equation. When I do that, the row in the join table is not deleted.

In the documentation it says:
"Changes made only to the inverse end of the association are not persisted."

Does that hold true for join table info or is my mapping screwed up?

Heres' the mapping:

MemberList.hbm.xml

<bag name="members" table="memberList_to_member" cascade="save-update" inverse="true" lazy="true">
<key column="memberListId"/>
<many-to-many class="org.groundspring.emailnow.model.Member" column="memberId"/>
</bag>

Member.hbm.xml
<set name="memberLists" table="memberList_to_member" lazy="true">
<key column="memberId"/>
<many-to-many class="org.groundspring.emailnow.model.MemberList" column="memberListId"/>
</set>

And it's hibernateSession.delete(memberList) that I'm calling.

I'm using hibernate 2.0.1 if that matters. I haven't had time to upgrade yet.

Thanks,
-mp

emmanuel · **Posted:** Tue Oct 28, 2003 1:26 pm

mpopetz wrote:

Does that hold true for join table info or is my mapping screwed up?

Yes

steve · **Posted:** Tue Oct 28, 2003 1:29 pm

Quote:

Does that hold true for join table info

Thats exactly what inverse="true" means for a many-to-many association (i.e., with an association table). Changes to the side marked inverse="true" will not effect the entries in the association table.

Quote:

And it's hibernateSession.delete(memberList) that I'm calling.

So is that trying to delete an instance of MemberList? If so, adn you want it ti also delete the related entries in the memberList_to_member table, set the cascaed attribute on MemberList.members to "all"...

mpopetz · **Joined:** Tue Oct 28, 2003 12:09 pm **Posts:** 46

won't cascade="all" cause my members to be deleted as well? I only want the links to be deleted...

-mp

gavin · **Posted:** Thu Nov 06, 2003 9:09 am

To delete all links of a many-to-many association, just dereference it.

Of course, you must use inverse="false".

mpopetz · **Joined:** Tue Oct 28, 2003 12:09 pm **Posts:** 46

I went ahead and dereferenced it from the inverse="false" side of things as a quick fix to my problem, but I guess my question boils down to:

If hibernate is told to delete an object, shouldn't it clean up join tables that it is handling? Otherwise it is leaving invalid data in a table and referenced from another object.

Is there a reason not to handle this case for users?

I'm trying to come up with a reason where a user would want to leave the reference there even though the data is invalid (and hibernate will ObjectNotFound if you try to load a collection with a reference to the deleted object).

Thoughts?
-mp

gavin · **Posted:** Thu Nov 06, 2003 9:25 am

You are, of course, supposed to remove the object you are deleting from any collections it belongs to, before deleting it. If you are using any other database than MySQL, you will get a FK violation if you do not.

trekmbikes · **Joined:** Thu May 05, 2005 4:49 pm **Posts:** 30

Can a hibernate expert please comment on why this shouldn't be implemented?

Quote:

If hibernate is told to delete an object, shouldn't it clean up join tables that it is handling? Otherwise it is leaving invalid data in a table and referenced from another object.

Is there a reason not to handle this case for users?

I'm trying to come up with a reason where a user would want to leave the reference there even though the data is invalid

I understand the inverse property and why the association shouldn't be updated twice. But when deleting the item, it seems like deleting either end of the Many-to-Many association should also remove the association.

Thanks!