many-to-one loads new instance for each row

jkeyes · **Joined:** Wed Nov 16, 2005 1:39 pm **Posts:** 3

Need help with Hibernate? Read this first:
http://www.hibernate.org/ForumMailingli ... AskForHelp

Hibernate version: 2.1.7c

Mapping documents:

I've stripped the example down to make it easier to understand:

Code:

<hibernate-mapping package="my.datamodel">
  <class name="HibFamilyData" table="FAMILY">
    <id name="id">
      <generator class="native"/>
    </id>
  </class>
</hibernate-mapping>

<hibernate-mapping package="my.datamodel">
  <class name="HibChildData" table="CHILD">
    <id name="id">
      <generator class="native"/>
    </id>
    <many-to-one 
          name="family" class="HibFamilyData" cascade="none">
      <column name="FAMILY_ID"/>
    </many-to-one>
    </class>
</hibernate-mapping>

Question
Say I have three child rows that have the same family_id, and I load each child [session.load(HibChildData.class, id)] row. When I do this I get a new instance of HibFamilyData for each row. I thought the HibFamilyData would be in the first level cache and therefore each HibChildData would have the same instance of HibFamilyData.

Can someone point out my error?

Thanks,
-John K[/code]

zzantozz · **Joined:** Fri Oct 28, 2005 10:46 am **Posts:** 37

You're certain that you're using the same Session to load all of them?

hhuber · **Posted:** Thu Nov 17, 2005 4:07 am

I'm not sure, but you might want to check your implementation of equals (and hashCode) in the class.
I'm sure that you need those for composite ids, but it may be that you've got the same problem here.

And the problem with equals and composite ids is that Hibernate just can't compare two ids as equal unless you implement equals correctly.

jkeyes · **Joined:** Wed Nov 16, 2005 1:39 pm **Posts:** 3

zzantozz, you're spot on.

jkeyes · **Joined:** Wed Nov 16, 2005 1:39 pm **Posts:** 3

zzantozz, you're correct. didn't spot that it was called createSession for each one!