Hello,

I have a one-to-many association between 2 objects:
Project ---> Baselines

in my project entity mapping, i have :

<bag name="bpbbaselines" inverse="true" cascade="all">
<key column="bpb_projects_t_id" />
<one-to-many class="com.ppc.paasmetrics.bo.bpbbaseline, com.ppc.paasmetrics" />
</bag>

in my baseline entity mapping i have

<id name="Id" type="Int32" column="bpb_baselines_t_id" unsaved-value="0">
<generator class="identity" />
</id>
<many-to-one name="bpbproject" column="bpb_projects_t_id" class="com.ppc.paasmetrics.bo.bpbproject, com.ppc.paasmetrics" />

I want to be able to delete the baselines collection and replace it with a totally new one, but for some reasons, every hting i tried did not work, and it keed adding the record in the DB, instead of deleting + adding new ones.

What I tried:

openSession();
_tx = _session.BeginTransaction();
project = (bpbproject) _session.Get(typeof(bpbproject), project.Id);
project.bpbbaselines.Clear();
project.bpbbaselines = null;
project.bpbbaselines = newbaselines;
_session.SaveOrUpdate(project);
_tx.Commit();

What am i doing wrong??

Thanks for your help,

Fabien

Try flushing the session immediately after the Clear() and before you re-assign the collection reference...

Tried that...not better...still add the records at the end as if the unreferenced collection was not doing anything...

Other ideas??
Thanks,

Fabien

I think the collection is lazy loaded. Try calling NHibernateUtil.Initialize(project.bpbbaselines) before you call clear

My collections don't use lazy-loading. But I still tried your suggestion...without success.

Is it somehting to do with the fact that the baselines table use identity key (MS SQL)?

I really don't know what's going on...

Thanks,

Fabien

Try using cascade="all-delete-orphan". Your current mapping allows baselines without parents.

And don't call Clear, just replace the collection with a new empty one.

No success. I get:
NHibernate.HibernateException: You may not dereference an collection with cascade="all-delete-orphan"



I removed the clear and put new ArrayList(); instead but no more success...

Do you have a working sample that works for you?? Maybe there's something obvious that I am missing.

Thanks,

Fabien

I have found that you can get the desired behaviour by setting cascade to all-delete-orphan and calling Clear() on the collection.

Correct solution i think has been posted in the message above
I would like to add something to explain better (i try! i'm a NH newbie as well)

1) NHibernate uses custom-collection classes even when they are not lazy, your ArrayList will be _anyway_ replaced with a class that keeps track of persistent instances

2) If you dereference the collection, the error message is obvious: you say to Nhibernate that you want to keep track of elements deletion ("all-delete-orphan") but you also destroy the collection object.. The semantics of delete managment is logically linked to the container collection, so CLEARING (0 elements) a collection is a thing, and dereferencing from the parent object has a really different meaning

In this scenario, NHibernate handled the problem correctly i think, i even noticed that the formal semantics of O/R mapping is well estabilished in NHibernate architecture, so there is no such space left for "interpretations of behiavour..."

Hope this can help,