Hi, I'm trying to do a very simple thing here. I have a main object that has many children. Lists and sets. When I get my main object, i initialize my child objects one by one. All lists come back with 3 objects regardless of how many are actually in the database. The only case thats correct is if there are 0 in the DB, 0 are returned.

Sets in the exact same code work fine. I'm stuck. Anything wrong in my mapping docs?



Hibernate Version
3.2

Mapping documents:
Parent



Child


Code between sessionFactory.openSession() and session.close():
I have a DAO that retuns the parent object.




Full stack trace of any exception that occurs:
No exception occurs. It just returns 2 empty child objects and 1 hydrated child object in the list. In the database theres actually only 1 child object

Name and version of the database you are using:
SQL Server 2000

The generated SQL (show_sql=true):



Debug level Hibernate log excerpt:
<attribute name="ShowSqlEnabled">true</attribute>


Problems with Session and transaction handling?

Read this: http://hibernate.org/42.html

A List actually has
- id columns (typically one)
- index columns - an integer storing the position of the element
- data columns

Remember that relations (database tables) don't store position information
so you need an extra column to get list semantics.

I guess your database does not distinguish between case for column names
so you actually mapped the id and the index attributes to the same column.

Nice one :-)

Shortly after posting this I did notice the same thing, I now have a SortOrder column as the index.

That did the trick - wow can't believe i missed that. But heres why I missed it, and it bubbles up another question. Im using the DAO pattern and saving child objects 1 at a time. Now, each child object has a parent object within it.

So I fill a child obj and say child.setParent(foobar) and I save it. Works fine.

Thats very differnt than saving the parent with a full collection of children. In which case, hibernate would do a delete all children, then insert children, incrementing the index all the time.

So outside of using a set, how can i use a List with a DAO pattern?? Hope i was clear, please reply if not clear.
Thanks


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So why don't you build your DAO pattern about the objects you want to model?

If it's the children, o.k..
But if the parent ist the center, so why don't you get the parent via dao, change the children you care about
and save again?

What i was asking was unclear. If i use a list within a parent object I think I have to treat that list as a whole list at all times because Hibernate manages the index column. I tried to save a single item in a list through the child DAO and it saved the index column as null.

As i understand it , hibernate saves lists as Delete all first, insert all second, keeping track of the index and incrementing all the way.

I changed my children to sets and its fine, so no worries.

But to answer your question, I could save the parent w/ modified children eveloped witnin, but that would be extra code when i could get at the single child i need through its own DAO.

Thanks