Hello All,

I have a table with a composite primary key consisting of two integer columns where one of them is auto-increment (SQL Server IDENTITY). I cannot change the database schema as this is a legacy database I have to support. The problem is, I cannot use <generator> inside <composite-id> anywhere. How do I solve this problem? Hibernate tries to explicitly write a value into auto-increment column when I save and there is no obvious way to tell it to stop doing that.

table def:

CREATE TABLE [SURVEY_ANSWERS] (
[ANSWER_ID] [int] IDENTITY (1,1) NOT NULL,
[STATUS] [int] NULL,
[QUESTION_ID] [int] NOT NULL,
[POSITION] [int] NULL,
[TEXT] [varchar](350) NULL,
[VALUE] [int] NULL

);
GO
ALTER TABLE SURVEY_ANSWERS
ADD CONSTRAINT pk_SURVEY_ANSWERS PRIMARY KEY(ANSWER_ID,QUESTION_ID);
GO


Thanks,

Denis.

It looks like you need to implement custom ID generator
http://www.hibernate.org/hib_docs/v3/re ... aration-id

Konstantin,

But <generator> can only be specified inside <id>, it is not allowed for <composite-id>, is it?

Denis.

You are correct, generator is for ID.

I looked at your problem again and now I do not quite understand why do you need to model your class with the composite key. It looks like DB identity column is the unique identifier for a row in the database. And question_id is just the FK to the question. Having them combined in PK does not make sense for me, but that does not matter much.

I suggest mapping as if ANSWER_ID is the sole ID of the answer and have Question mapped as normal many-to-one property.


If you still decide that you need to have composite key, then you may want to investigate org.hibernate.event package
http://www.hibernate.org/hib_docs/v3/re ... ate-events
and may try to define custom class for the identifier…

Thanks a lot, Konstantin. I will use the approach you suggested.