[ojb-users] Re: Error in 1:n mapping using ODMG API

[Lorenzo N. <ln...@we...>]

I hope this is not a FAQ :-)

> From: "Govindarajan S (Gover)" <gov...@az...>
> To: obj...@li...
> Date: Wed, 5 Jun 2002 18:58:37 +0530
> Subject: [ojb-users] Error in 1:n mapping using ODMG API

Hello,

> I get the following exception when using the ODMG API for persisting
> the 1:n mapping. I have a product group class which has a collection
> of articles. Iam trying to persist the ProductGroup. As expected it
> tries to persist the Article as well. But during the process i get the
> following exception message,
> 
> [ojb.broker.singlevm.PersistenceBrokerImpl] ERROR: Error in
> Transaction abort: General error: Warning:  Some non-transactional
> changed tables couldn't be rolled back
> org.odmg.TransactionAbortedException: Invalid argument value:
> Duplicate entry '71' for key 1
> [...]

> From what i observed its trying to insert the article, which is
> already inserted. I took a look at the SQL queries submitted to the
> database and found this,
> [...]
> At this stage an SQLException is thrown.
> 
> What could be going wrong? why is it trying to insert the first
> element again?


I'm experiencing a similar problem, persinsting the classic 1:n 
mapping: 1 Order to n. tems
(using OJB v.0.9)

I made the association navigable in both directions: 
in Order there is a collection of Items AND in the Item there is the 
FK to Order + the reference to the Order
Both tables PK are autoincrements.

If I set the collection of Items in Order for auto-update, when I insert 
a new Order (with new Items), OJB tries to insert duplicate Items 
(with the same PK) causing the exception.
Setting "auto-update" to false eliminates the problem! ( sadly, the 
auto-update feature could be useful :-( )

Here is the (very simplified) classes code:
----------------------------------------------------------
public class Order 
{
	private int id;
	private Vector items;
	[...]
}

public class Item
{
	private int id;
	private int orderId;
	private Order order;
	[...]
}
----------------------------------------------------------

And the (very simplified) mapping is this:
----------------------------------------------------------
<class-descriptor class="test.Order" table="_Orders">
      <field-descriptor id="1"
         name="id"
         column="id"
         jdbc-type="INTEGER"
         primarykey="true"
         autoincrement="true"
      />
	[...]
      <collection-descriptor name="items" 
	    element-class-ref="test.Item"
         auto-retrieve="true" auto-update="true" auto-delete="false"
      >
         <inverse-foreignkey field-id-ref="3"/>
      </collection-descriptor>	  
</class-descriptor>

<class-descriptor class="test.Item" table="_Items">
      <field-descriptor id="1"
         name="id"
         column="id"
         jdbc-type="INTEGER"
         primarykey="true"
         autoincrement="true"
      />
     [...]
      <field-descriptor id="3"
         name="orderId"
         column="orderId"
         jdbc-type="INTEGER"
      />
      <reference-descriptor name="order"
         class-ref="test.Order"
      >
         <foreignkey field-id-ref="3"/>
      </reference-descriptor>
</class-descriptor>
----------------------------------------------------------
[I removed fileds and references that doesn't have anything to do 
with the problem]

THIS mapping will cause the problem inserting a new Order. 
Changing "auto-update" to "false", in the "collection-descriptor", will 
not.

Is is an OJB problem? 
Or is it a logic problem in the mapping?

Bye
	Lorenzo






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