Child collections management by multiple parent entities

midtown_hibernate · **Joined:** Wed Sep 16, 2009 11:42 am **Posts:** 1

I have a dependent entity named ChildEntity with two parents ParentEntity1 and ParentEntity2. So,the structure something like this

Code:

ParentEntity1{
 List<ChildEntity> children;
}

ParentEntity2{
 List<ChildEntity> children;
}

ChildEntity{
 int sortOrder;
 // back pointer
 ParentEntity1 parent1;
 ParentEntity2 parent2;
}

The mapping works good with child collection as part of only one parent but when I change it for both parents to have this collection it is breaking.. I mean in the above classes, the 'children' collection can be only at either ParentEntity1 or ParentEntity2 then it works otherwise it breaks.

Some details about mapping:
ChildEntity.hbm.xml

Code:

<many-to-one name="parentEntity1" class="ParentEntity1" insert="false" update="false" column="PARENT1_COLUMN" />
<many-to-one name="parentEntity2" class="ParentEntity2" insert="false" update="false" column="PARENT2_COLUMN" />
[i]<property name="sortOrder" column="SORT_ORDER" type="integer" insert="false" update="false"></property>[/i]

ParentEntity1.hbm.xml

Code:

<list name="children" table="CHILD" cascade="all-delete-orphan" batch-size="20">
    <key column="PARENT1_COLUMN" not-null="true"></key>
    <list-index column="SORT_ORDER"/> 
    <one-to-many class="ChildEntity"></one-to-many>
</list>

and ParentEntity2.hbm.xml

Code:

<list name="children" table="CHILD" cascade="all-delete-orphan" batch-size="20">
    <key column="PARENT2_COLUMN" not-null="true"></key>
    <list-index column="SORT_ORDER"/> 
    <one-to-many class="ChildEntity"></one-to-many>
</list>

When I run this it is giving an error, which is a bit misleading:

Code:

Caused by: org.hibernate.MappingException: Repeated column in mapping for entity: com.hbo.it.go.profile.tray.model.TrayItem column: SORT_ORDER (should be mapped with insert="false" update="false")

Any thoughts?

Froestel · **Posted:** Wed Sep 16, 2009 12:13 pm

Hi midtown_hibernate,

this looks like bad programming style to me (or you're leaving something out).

Why don't you have a common super class for your two parent entities and let the child reference that super class?

CU
Froestel