I am sure that this just isn't possible but before I give up on it, I thought I would ask here.

I have a class Order mapped in one session factory to a table Order in Database1.

I have another class Category mapped in another session factory to a table Category in Database2.

Order has a property of type Category.

Assuming that these two classes MUST be mapped to different tables in different databases for legacy reasons, how can I get Order to persist to Database1 persisting the Catagory reference to a simple CategoryId column without throwing "An association from the table Order refers to an unmapped class: Category "?


The only answer I can comeup with is:
Just persist the Category Primary Key, then you can just call it out when needed.


Thanks in advance.

hello

Out of the box, hibernate does not make cross factory management (None that am aware of). However, you could probably play with the event api of Hibernate to do special operation when you object are persisted / loaded.


If you databases are on the same server, with same user / access rights (eg 2 mysql db you have access to, or 2 oracle namespaces), you could try to have only one factory (accessing database1) but with references to tables in the form database2.someTable May be this could do the trick. (This will only work if you can issue a "select * from database2.someTable" while connected to database1).

You can solve it with custom type:
1. Write a custom type, which will read Category Id from recordset and load necessary Category object from Session 2 (created by Factory 2). For saving it will save the Id of the Category object to the table. Essentially - the same in reverse order.
2. Map your property as a "property" (not "many-to-one", etc.) and specify your custom type.
It shoud be enough.

In general, it's almost your solution "just persist the Category Primary Key", but you will not have to load objects manually.

Please note, that this mapping is not a mapping between entities, so you will have to take care of cascading issues by yourself.