Problem is as follows: I have a legacy oracle db structure (that may not be changed). All the relevant tables do not have PK's and all the tables' are nullable (don't know if that's relevant).

I want to use Hibernate as a simple read-only facade to the database. When I use the hibernatetools (eclipse plugin) to generate code, i get sensible results (unfortunately I cannot attach full code/db configuration because of confidentiality). The mapping file contains a composite key containing all the columns of the DB. The Java files seem to be generated correctly - there are setters and getters for the PK in the main class and the PK class implements equals and hashCode.

Hibernate version: 3.1.3

Mapping documents:

Code between sessionFactory.openSession() and session.close():


That returns a list where list.size == 1 and list.iterator().next() == null.
If I do a query that should return a number of elements, I get the correct size list but all items are null.

Name and version of the database you are using:
Oracle 9i 9.2.0.7.0

Debug level Hibernate log excerpt:


--snip--


As you can see, hiberante correctly reads the data from the DB, but still a null is returned. I have no idea why. No information with WARN or higher priority is written about this in the logs. I get no stack trace.

While I'm certainly not a hibernate expert, I've spent a considerable amount of time trying to solve this, and currently I assume it's a hibernate bug (i.e. returning nulls without any warning is unexpected behavior). Perhaps it occurs when there are no fields outside the composite ID.

what's in the index column for that row of data?

How can I find that out? I'm not very experienced in dealing with DBs.

I'm using SquirrelSQL to read the (meta)data from DB, this is what is listed under the "Indexes" view at the table level:

INDEX_QUALIFIER=<null>
INDEX_NAME=<null>
ORDINAL_POSITION=0
COLUMN_NAME=<null>
ASC_OR_DESC=<null>
NON_UNIQUE=0
TYPE=0
CARDINALITY=66394
PAGES=3754
FILTER_CONDITION=<null>

there is only one row in the Indexes view.

Thanks for your answer.

sorry, I don't mean the database index. If you are using the List collection from hibernate, in the mapping files (*.hbm.xml) it requires you to specify an index column for the table. If there is anything other than a 0 in that column for that particular row, that could explain why you are getting a null value.

Sorry, I'm a bit lost here. The mapping file is like this (a few irrelevant things are replaced with "xxx"):


There is no other elements than those listed above (specifically, there are no associations defined, which is fine for now).

I did a quick search to the hibernate documentation, and specifying an index is mentioned when mapping collections (which I don't need to do here) - I didn't find other information about that there.

Also, I'm not explicitly using any hibernate-specific collections. As you can see from the code in the first post, I just ask for the results as a List (java.util.List).

I'd appreciate if you could provide a link to the relevant part of documentation or an example code snippet. I've done similar things (e.g. Middlegen + hbm2java) and never run into this problem (the difference beign that in those cases there were a single ID column defined in the DB).

ohh, sorry. I thought you were dealing with a collection in a class

That's ok, I appreciate the time you took to try to help me anyway :). Thanks for that.

Please enter all the data's in all the columns and run ur query.
This time i think u should not get null references.