Hi all,

does anyone have som good pointers on how to handle if, for example, you need to refactor your models, which leads to changed hbm-files and your database has data that must be migrated with the new scheme.

Can Hibernate do something to help out, is there any tools which simplifies the job or is this still manual work to do?

Greatfull for any help.

/Manny

middlegen will construct hbm.xml files from your database. You must specify many-to-many tables manually, but (if you have added the correct foreign keys to the database) it will deduce one-to-many joins correctly.

Since those hbm.xml files have extra markup, the hbm2java tool can create POJOs from the generated hbm.xml. The POJOS will contain xdoclet Hibernate markup so that hbm.xml can be generated from the POJOs.

Then you can diff the generated POJOs against your existing POJOs, and make necessary changes by hand.

If your table structures haven't changed, but have just been moved into different schema, it's even easier. Just add schema="new_schema" to your existing xdoclet markup or hbm.xml files.

My problems are that I can't take the old data and import it into the new databse which is slightly different. I suspect that there are circular dependencys that psql fails on but I'm not sure.

As hibernate uses constraints I cannot import one table at the time and I'm now running out of ideas on how to get the data into the new database.

After some days I found that to me it took quite some effort to get things working. Hopefully I now have a way of updating databases with changed design so I don't have to go through this again. :)

I dumped the new database scheme and manually deleted all constraints which give me the oppurtunity, for example, to update a table at a time from the old databases tables. (The ones that was unchanged).

After my changes were made I updated the database with the new databse scheme that has all the constraints intact and after some tries I got things working.

/Manny