Repeated column in mapping for collection

DaVinci79 · **Posted:** Wed Dec 21, 2005 12:22 pm

Hey everyone

I have the following mapping:

Code:

<class name="Order" table="SalesOrder">

   <list name="_orderLines" access="field" table="OrderLines" cascade="all" lazy="false" inverse="true">
      <key>
         <column name="orderId"/>
      </key>

      <index column="sequence"/>

      <composite-element class="OrderLine">

         <many-to-one access="field" name="_order" column="orderId" class="Order" not-null="true"/>

      </composite-element>
   </list>

</class>

It gives me the following error:

Code:

Exception in thread "main" org.hibernate.MappingException: Repeated column in mapping for collection: nl...domain.Order._orderLines column: orderId
   at org.hibernate.mapping.Collection.checkColumnDuplication(Collection.java:275)
   at org.hibernate.mapping.Collection.checkColumnDuplication(Collection.java:298)
...

Which is probably totally valid. But how can I mantain a reference from the OrderLine to the Order without creating an additonal column? Am I missing something?

Thanks in advance,
Vincent

Hector_Lopez · **Posted:** Wed Dec 21, 2005 12:52 pm

Remember that composite-elements are value objects, and that means they'll be stored in the same table as the owning entity (the list), so you end up with 2 columns named orderId.

If you want to navigate from and OrderLine to an Order, consider dropping the composite-element or wait for a better answer ;-)

Bye.

DaVinci79 · **Posted:** Thu Dec 22, 2005 4:33 am

Well, because I specified the 'table' element in the list, it would store the elements of the list in a different table. Besides that the sequence together with the orderId would become a composite key (kind of). I'm currently in the process of refactoring the database and giving hte composite element class its own <class></class> tags. Still, it seems to me that this should be possible, because the class is in fact in a different table.

Hector_Lopez · **Posted:** Thu Dec 22, 2005 4:40 am

Even if the list resides in its own table, that table has an id (named orderId) and the many-to-one (that resides in the same table) has another id column (named orderId also). That's why hibernate complains.

Bye.

DaVinci79 · **Posted:** Thu Dec 22, 2005 8:40 am

Yes, but the orderId used to maintain the collection and the back-reference are the same... they should be the same. So, I don't want to create two the same columns, I just want to use it twice: as a reference to the order, and to maintain the order -> orderLine collection. The only difference is that I use composite-element instead of a separate class definition. The advantage would be that I can use the columsn sequence and orderId as a composite key for free.