Delete Cascade and Composition problem.

Question

As it's well known into a DB You can have more than one Fk and more than one FK could have Delete cascade set.
A typical situation is an intersection table between 2 tables wich solves a N to M relationship.
In BC4J is impossible to manage that situation because Delete Cascate is related to composition and composition tries to lock the owning entity (JBO-25030) however if we try to get the detail row from a ViewLink the other one is invalid and viceversa.
How can I solve that issue ?
I read the Steve's http://radio.weblogs.com/0118231/stories/2003/01/17/whyDoIGetTheInvalidownerexception but we normaly don't know, at the create monent all values (the user should select them) and then the createAndInitRow is not a good solution.
Could someone help.
TIA
Tullio

Answer 1

I've the same Problem and solved it the following way:
Assuming you have the following VOs:
MasterView1
MasterView2
IntersectionView
and two Associations of the composition type (each with the Cascading Delete Option between them):
Ma1InterAssoc
Ma2InterAssoc
If you first select a row in MasterView1 and in MasterView2 you can create a new Row in IntersectionView as both "owning Entities" now have a valid current row. BC4J automatically creates the keys to the two Master Entities for you in the Intersection Entity.
MasterView1Impl vo1 = getMasterView1();
vo1.selectMyRow(...);
vo1.executeQuery();
vo1.next();
MasterView2Impl vo2 = getMasterView2();
vo2.selectMyRow(...);
vo2.executeQuery();
vo2.next();
IntersectionView detVo = getIntersectionView);
Row detRow = detVo.createRow()
detRow.setValueX(...); // it is important to set at least one value!!
detVo.insertRow(detRow);
This method works well since JDeveloper 9.0.3, but unfortunately it is not officially supported by Oracle, so you do it on your own risk :(
Hope it helps
Frank