A simple many-to-one association stumps me!

liem · **Joined:** Tue Jun 14, 2005 12:14 pm **Posts:** 37

Hibernate version: 3

Mapping documents:

Code:

<hibernate-mapping>
    <class name="UserPermissions">
       <id name="id" column="userpermissions_id">
                  <generator class="native"/>
        </id>          
   <!-- Device -->
        <many-to-one name="device" column="device_id"/>

   <!-- UserGroup -->
        <many-to-one name="group" column="usergroup_id"/>

   <!-- User -->
        <many-to-one name="user" column="user_id"/>
    </class>
</hibernate-mapping>

If one of the device, or usergroup, or user from the above mapping is null, saving UserPermissions gives me "TransientObjectException: object references an unsaved transient instance". Is it possible to have a null foreign key?

Thanks in advance,
Liem[/code]

steve · **Posted:** Thu Nov 03, 2005 11:42 pm

Check the documentation regarding cascading. That error has nothing to do with a <many-to-one/> reference being null...

liem · **Joined:** Tue Jun 14, 2005 12:14 pm **Posts:** 37

steve wrote:

Check the documentation regarding cascading. That error has nothing to do with a <many-to-one/> reference being null...

Hi Steve,

Thanks for replying. But, unless I am smoking something, I notice that Hibernate puts an fk constraint on the foreign key device_id; so, of course, when I try to save a UserPermission record with a null Device, it gives me the mentioned error, correct?

Liem

matt_mcgill · **Joined:** Wed Jul 13, 2005 2:18 pm **Posts:** 44

liem wrote:

so, of course, when I try to save a UserPermission record with a null Device, it gives me the mentioned error, correct?

Liem

Nope - that exception is a result of sticking a transient object into a set on a persistent object without calling session.save() on the transient object or defining a cascade behavior on the object containing the set. Read about the cascade attribute, as suggested. Setting it correctly should fix things.

liem · **Joined:** Tue Jun 14, 2005 12:14 pm **Posts:** 37

Yup, I am an idiot! Figured one cascade that is the culprit. Thanks.

Liem