Bidirectional relations are not updated inside transaction

polar · **Joined:** Fri Sep 26, 2003 7:08 am **Posts:** 7

Hello all!

I'm using Hibernate with MySql DB server, which maintains tables in InnoDB mode, i.e transaction support is on.
I have two object with parent-child relationship: Model and Entity.
Here are fragments of Model.hbm.xml:

Code:

...
      <id column="MODEL_ID" name="id" type="java.lang.Long">
         <generator class="native"/>
      </id>
...
    <bag name="entities" inverse="false" lazy="false" cascade="all">
         <meta attribute="use-in-tostring">true</meta>
         <key column="MODEL_ID"/>
         <one-to-many class="com.XXXXX.Entity"/>
    </bag>

Here are fragments of Entity.hbm.xml:

Code:

...
      <id column="ENTITY_ID" name="id" type="java.lang.Long">
         <generator class="native"/>
      </id>
...
      <property column="MODEL_ID" length="11" name="modelId" not-null="false" type="java.lang.Long">
         <meta attribute="use-in-tostring">true</meta>
      </property>

So, Model can have a number of Entities-children.
Problem is following. I begin transaction like that:

Code:

    Session session = null;
    Transaction tx = null;
      try {
      session = manager.obtainSession();
      tx = session.beginTransaction();

than pass newly created Model object with collection of Entities to create method. After it I use session.load(classname, ID) to receive my Model object back. I expect all auto-generated ID fields to be set by proper values. But effect is partial - all ID fields are really set to proper values - either in Model(parent) or in Entitiy(children). BUT! Field modelId in Entity(child) remains NULL, but I expect it to be set to Model Id value.
If I commit session - all became proper (after re-reading from DB using another session). But I need these values inside of initial session! Searching for solution of description of such problem has no success.
Is this a bug, or feature, or maybe I do something wrong?
Thanks in advance for help

cutie · **Posted:** Thu Oct 23, 2003 3:20 pm

Wouldn't you want a

Code:

<many-to-one
         name="model"
         class="Model"
         column="MODEL_ID"
         not-null="true"
         />

instead of

[code]

polar · **Joined:** Fri Sep 26, 2003 7:08 am **Posts:** 7

cutie wrote:

Wouldn't you want a

Code:

<many-to-one
         name="model"
         class="Model"
         column="MODEL_ID"
         not-null="true"
         />

instead of

[code]

cutie · **Posted:** Thu Oct 23, 2003 5:29 pm

did you try flushing the session after saving the new instance and before reloading it? Hibernate is able to generate ids without hitting the database with its hilo algorithm but anything generated by the database wont get set until the database is hit, which only happens when the session is flushed/closed.

polar · **Joined:** Fri Sep 26, 2003 7:08 am **Posts:** 7

cutie wrote:

did you try flushing the session after saving the new instance and before reloading it? Hibernate is able to generate ids without hitting the database with its hilo algorithm but anything generated by the database wont get set until the database is hit, which only happens when the session is flushed/closed.

I cannot flush session, because I have some other task to do with this objects - Model etc... This task requires full objects - with all ID set, but if this task fails - I should have ability to rollback changes made to DB...

emmanuel · **Posted:** Thu Oct 23, 2003 6:24 pm

polar wrote:

I cannot flush session, because I have some other task to do with this objects

So what ? you can continue using thoses objects after session.flush().

polar wrote:

but if this task fails - I should have ability to rollback changes made to DB...

That's the purpose of tx.rollback().

polar · **Joined:** Fri Sep 26, 2003 7:08 am **Posts:** 7

epbernard wrote:

polar wrote:

I cannot flush session, because I have some other task to do with this objects

So what ? you can continue using thoses objects after session.flush().

polar wrote:

but if this task fails - I should have ability to rollback changes made to DB...

That's the purpose of tx.rollback().

I'll try this tomorrow.. We have 1.40am now :-) But AFAIR from Hibernate Javadoc - flush method should be used directly before session.close()...
But I'll try .
Tnx

polar · **Joined:** Fri Sep 26, 2003 7:08 am **Posts:** 7

Nothing happend using session.flush() :-( Effect remain - no parent ID is set in children objects.
Can anyone tell me how to omit such situation?

Brannor McThife · **Posted:** Fri Oct 24, 2003 7:12 am

I won't give the reasons why I have something similar, but suffice to say, I think I know what you need to do in your code.

As you're not using inverse, there is a way to get around this, but it involves not using cascade.

1) Remove cascade="all" from your bag.

2) Then, in your code, do something like this (which is really the non-cascade way the reference material talks about):

Code:

...
session.save(model);

List entities = model.getEntities();
For (int i = 0; i < entities.size(); i ++) {
    Entity entity = (Entity) entities.get(i);
    entity.setModelId(model.getModelId);  //manually setting Foreign Key
    //this bit may not be needed.....
    entity.setModel(model);
    model.getEntities.remove(i);
    model.getEntities.add(entity);
    //.....
    session.save(entity);
}
...

As I said, this is a workaround, where you manually set the foreign key for each child. Try this, and perhaps it works.

-G

polar · **Joined:** Fri Sep 26, 2003 7:08 am **Posts:** 7

This is very rude decision :-) I've almost done using session.refresh(). After using session.update() I need just use refresh() to every entity in order to get modelId set (iterate through model.getEntities()). And do so with every entity collection - I have three of them :-(. It is not so beatiful decision, but it is IMHO better than "hands" one.
Iteration through children must be done because refresh does not use cascades (it could be seen by swtching "show sql" property in hibernate.properties to true).
Thanks to everyone for help