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Hibernate version: 3.2.5.ga

Name and version of the database you are using:MySQL 5.0.18

Hello All,

I am new to hibernate so please excuse any broach in protocol. I have a uni-directional List of objects that I have mapped as one to many (mapping code to follow)



My test executes the following code:


I am getting the following exception when I attempt to remove an item from the list:


I am certain that there is user error involved here, but after searching the forums and Google all day I haven't gotten any lead on what I might be doing wrong.

If anyone can offer any advice or insight either into my issue specifically or mapping Lists that I might have missed I would appreciate it.

Thank you for your help,
Dave

Hi,

I would try 2 things:
1. Remove your final declaration,
2. Remove your session.delete(..)

rgds,

Hello,

I tried removing both the final qualifier and the session.delete() call. Neither had any effect on the behavior I am seeing. Thank you very much for the advice though.

Dave

You don't need the delete line neither the saveOrUpdate line. Just remove the entity from list and flush the session, commit the transaction. Hibernate will take care of deleting the child from database since you have specified DELETE_ORPHAN cascade option.


Farzad-


ps. If this still doesn't work give a sample code that doesn't work and I will change it in a way it works.

Thank you for the advice about removing the delete call. I was just reading about transitive persistence and it too mentioned that merely removing the item from the collection should be sufficient to trigger a delete.

I modified my test code to look like this:


Unfortunately I am still seeing the same exception at run time that I originally noted:



This is the mapping code I have for the list I am attempting to remove from:

If u don't mind may i know the List implementation class u have initialized in ur POJO class. In general collections throw such kind of error(UnsupportedOperationException) when their implementation class does n't support remove() method. So, plz make sure ur collection supports it or not.

Plz reply me.

I believe it has something to do with your list instance as the other guy pointed out. I did a little test with your code and it seems to be happily working for me. I did it in JPA but there is hardly a difference here for you:



and



and the test code is:



and it runs with no problem.


Farzad-

I re-wrote my test to use the EntityManager like you suggested and it ran correctly for me as well. Does anyone have any idea why the EntityManager can execute this code but the SessionFactory seems to have problems? Can anyone else see if they can reproduce the behavior I am seeing with the SessionFactory?

Thanks,
Dave

I think I figured out what is going on and why the EntityManager code appeared to work where the SessionManager did not.

In the setUp() method for my test there is code that adds a new Container and a list of Widgets. This graph is being persisted to the database with a session.save() call and the whole thing was wrapped in a begin/commit transaction block. I assumed that this would be all that was necessary to persist the data to the database and then fetch it back to modify it.

What I found was that Hibernate was not persisting the data when the commit() call was made and when I went later on to access the list I was getting something from the 1st level Session cache (even with this knowledge I'm a little unsure why the list seemed partially populated, but all the dark magic that goes on with hibernate caching is still somewhat unclear to me).

I believe that the test was working with the EntityManager because I was then closing the Session and opening a new EntityManager connection. I think the close() call was causing a flush to occur on the original session and the data to be sent to the DB.

In short what I did was add a session.flush() after the commit() call to my setUp() method and my code executes correctly with the SessionManager now.

I guess I need to do some more reading about transactional control and the flush() method.

Thank you all for your advice on help with my question. I look forward to participating in this forum more (hopefully adding knowledge rather than confusion, eh?) :-)

Thanks,
Dave