Hi,

I'm very new, so please bear with me. I've got two tables
user_groups and user_group_hierarchies. The later has two
foreign keys (parent_id, child_id) to the primary key of the
former (user_groups) table. This allows user_groups to be
placed in a tree structure. I'm trying to return the parent_id
as part of the user_group data when I query for user_groups.
I thought to make a one-to-one association between the
user_group and the child_id in the hierarchy table. My current
arrangement is throwing an exception in hibernate code (I'm
using 2.1rc1). Details of my situation are below.

A couple of things occur to me: (a) I'm doing
this one-to-one thing wrong; (b) the association should be
another kind of association; (c) possibility of adding a parent_id
to the user_groups table; and (d) waiting for a hibernate
bug to be fixed.

Thanks for any help.
-Brandon

My hibernate descriptor file looks like this:

<class name="UserGroupEntity"
table="USER_GROUPS" dynamic-update="true">

<id name="id" column="id" type="long">
<generator class="sequence">
<param name="sequence">security_seq</param>
</generator>
</id>

<property name="name" column="NAME" type="string" />
<property name="description" column="DESCR" type="string" />
<property name="path" column="PATH" type="string" />

<one-to-one
name = "parent"
class = "UserGroupHierarchyEntity"
cascade = "none"
property-ref = "childGroupId"
/>

</class>

<class name="UserGroupHierarchyEntity"
table="USER_GROUP_HIERARCHIES" >

<composite-id >
<key-property name="parentGroupId" />
<key-property name="childGroupId" />
</composite-id >

<property name="parentGroupId" column="PARENT_GROUP_ID" type="long"
insert="false" update="false" />
<property name="childGroupId" column="CHILD_GROUP_ID" type="long"
insert="false" update="false"/>

</class>


When I run this I get an exception:

[2003-12-03 15:41:19,564] ERROR [STDERR ] net.sf.hibernate.MappingException: bug in initComponentPropertyPaths
at net.sf.hibernate.persister.AbstractPropertyMapping.initComponentPropertyPaths(AbstractPropertyMapping.java:140)
at net.sf.hibernate.persister.AbstractPropertyMapping.initPropertyPaths(AbstractPropertyMapping.java:111)
at net.sf.hibernate.persister.AbstractPropertyMapping.initPropertyPaths(AbstractPropertyMapping.java:80)
at net.sf.hibernate.persister.AbstractEntityPersister.initPropertyPaths(AbstractEntityPersister.java:503)
at net.sf.hibernate.persister.EntityPersister.postInstantiate(EntityPersister.java:112)
at net.sf.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:155)
at net.sf.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:720)

This has an embedded exception which looks like this:
Caused by: java.lang.ArrayIndexOutOfBoundsException: 1
at net.sf.hibernate.util.ArrayHelper.slice(ArrayHelper.java:61)
at net.sf.hibernate.persister.AbstractPropertyMapping.initComponentPropertyPaths(AbstractPropertyMapping.java:135)

Remove


You already mapped parentGroupId; and childGroupId java properties in the composite-id

Yes, you can't map the same property twice!

I was trying a bunch of different things to see how they worked.
I'm not exactly sure, but I think I had the properties in addition
to the composite id because I was getting a error that said that
it couldn't find the properties.

My real question is: Is the one-to-one association the right thing
to use in this case?

fyi, this exception also occurs if you have a column in your table named the same as the table. Needless to say it's probably pretty weird to have a column named the same as the table and we ended up renaming ours so that this isn't an issue. It did however cause me to bark up the wrong tree for awhile trying to figure out what was going.

I ended up using formula properties. That worked fairly well.

Would you mind posting the mapping files you ended up with?

Thanks.

As the doc says, you have purely derived properties based on a sql query. Two I'm using look like this:

<property name="childCount" insert="false" update="false"
formula=
"(select count(*) from user_group_hierarchies ugh where ugh.parent_group_id = id)"
/>

<property name="parentId" insert="false" update="false"
formula=
"(select ugh.parent_group_id from user_group_hierarchies ugh where ugh.child_group_id = id)"
/>

where id is the column name of the primary key of my class. Hibernate places those queries as column subqueries in the query it constructs.