Delete entity that participate in many to many association

Question

Hi all,
I have two tables related by a many to many relationship (for ex department and employee).
So I have three tables:
Department: table of departments
Employee: table employees
deptEmp: the association table relating the employees to the departments.
When a department is deleted, all the corresponding rows in deptEmp table should also be deleted (and same for employee).
On the entity level, I have created the many to many association (between department and employee) and a one to many association for each of department and employee entities to deptEmp entity (deptEmptAssoc from department to deptEmp and empDeptAssoc employee  to deptEmp).
I configured the deptEmptAssoc association to be a composition and implement the cascading delete, and it is working fine. When I delete a department, the corresponding rows in deptEmp are deleted.
The problem is that when I try to do the same for empDeptAssoc, JDev gives me a warning and doesn’t apply the composition neither the cascading delete.
I tried to override the remove method of employee entity to also remove the corresponding deptEmp but it also didn’t work.
So any hint or pointer how to achieve this? How to have a many to many association and be able to delete both sides of the association?
Thank you.

Answer 1

Hi,
This behavior can be done by overriding the postChanges method as follow:
  public void postChanges(TransactionEvent transactionEvent) {
        if(getPostState() == STATUS_DELETED){
            RowIterator mmIterator = getMM();
            while (mmIterator.hasNext()){
                EntityImpl row = (EntityImpl)mmIterator.next();
                row.remove();
row.postChanges(transactionEvent);
        super.postChanges(transactionEvent);
N.B.1  In the xml file of the viewLink, the composition association (and implement cascade delete) should not be checked.
N.B.2  with these flags unchecked, ADF will not control the posting of entities in case the department and the deptEmp entities were both newly created. To fix the issue, the deptEmp entity should also override the postChanges method as follow:
                    public void postChanges(TransactionEvent transactionEvent) {
        if (getPostState() == STATUS_NEW ||
              getPostState() == STATUS_MODIFIED) {
            EntityImpl dept = getDept();
            if (dept != null) {
              if (dept.getPostState() == STATUS_NEW) {
dept.postChanges(transactionEvent);
                                                // do the same for the Employee entity if needed
        super.postChanges(transactionEvent);
Regards.