I'm definitely quite stuck working with persistent lists. The XML mapping of the entities involved are as follows:

<class name="A">
...
<list name="carichiInCoda" table="codacorsia" access="field">
<cache usage="read-write"/>
<key column="corsia" not-null="true"/>
<index column="listIndex"/>
<many-to-many column="carico"
class="C" />
</list>

</class>

<class name="C" abstract="true">
...

<joined-subclass name="C1" dynamic-update="true">
<key column="id" ></key>
...
<list name="scarichi" access="field" cascade="all">
<cache usage="read-write"/>
<key column="carico"/>
<index column="scaricoIndex"/>
<one-to-many class="C2"/>
</list>

</joined-sublcass>

<joined-sublcass name="C2">
...
</joined-subclass>
<class>

..............
Subclass C1 has a list of subclasses C2.

Summing up, relations between A, C, C1 and C2 are as follow


| A | <>-----> | C |
^
<extends>
|
-----------------
| |
| C1 | <>------->| C2 |


What I'm trying to do is removing a subclass of C (class C1) from the list "carichiInCoda" of an instance of A and then to add another subclass of C (class C2) into the list "carichiInCoda" of a different instance of A. The process runs within a single transaction (handled by an open session in view like pattern implemented in Wicket) and it can be summed up as:

c1 = new C1();
c1.getScarichi().add(c2)

a1.getCarichiInCoda().remove(c1)
a2.getCarichiInCoda().add(c2)

where a1, a2 are instances of A, c1 is instance of C1 and c2 is instance of C2

Setting Hibernate to show SQL statements, i can clearly see that it
executes the command for the removal of c1 from the persistent
list of A ("DELETE FROM codacorsia WHERE .....") but there's no trace of
adding c2 into the persistent list of a second instance of a2.


Note that a1, a2 and c1 are instances managed by hibernate, while c2 is
created by the new operator and relies on cascading="all" specified in the
C1.scarichi mapping. Cascading proves to be working and by all means also
the A.carichiInCoda works and is tested in these other transactions:

- adding and removing an element from an A.carichiInCoda collection
- removing a c from a1.carichiInCoda and inserting c into a2.carichiInCoda

The only difference that comes up to my mind is that I'm trying to insert
a yet-to-be-persisted instance of C into the collection. I've tested that
if I commit the transaction before a2.getCarichiInCoda().add(c2) and do
this last operation in another one everything works fine (i.e mapping
should be correct). Simply flushing doesn't work though.

Is there a reason why doing it in a single transaction shouldn't work? I
hadn't problem like this one before...it seems a really odd behaviour.


Thanks for any kind of clarification, I hope i have been clear enough...