Hibernate version: 2.1.8

Mapping documents:

I have a bidirectional one-to-one mapping between Group and a GroupRSSChannel realized with many-to-one on the Group and one-to-one + property-ref="group" on the GroupRSSChannel.

The mappings are below:



and in Group mapping:



My problem is that if I make both classes cachable, when I list the groups Hibernate will issue a select from Group for each propertyRef from the GroupRSSChannel. If I remove the bidirectionality (thus the propertyRef statement) everything works as expected, groups come from the query cache, no statement is issued to the DB.

Am I doing something wrong (most probably), or this is the expected behavior (one select from db for each property-ref) the property-ref shouldn't come (or can't be obtained) from the cache ?

Thanks in advance.

second-level caching based on property-refs has not yet been implemented. Currently, the second-level cache exclusively uses the id value to cache the entities.

Hmm, good to know, thanks. I'll try to avoid this in the future, I didn't know.

Which are the best practices though when you need let's say three bidirectional one-to-one relationships from User to Address, let's say billingAddress, homeAddress and deliveryAddress ? I've allways solved this with fk from user to address and created three "fake" sublcasses for each type of address and referenced the user back from address with a property-ref but this is clearly and simply not the way to go when you want caching to work as expected (if you need to list 10 users on a page you'll get 30 selects for displaying that page mistake which I won't repeat in the next 20 years).

The first thing that comes to mind to fix this is proxying the Address with an interface so that it won't be loaded at user load unless specified ?

PS. I promiss I won't hack again. I didn't listen to hibernate docs which call one-to-one by FK practice "hacking" but I really didn't know how to solve this problem otherwise. With one-to-one with primary key you can map only one user to one address.

thanks again

If you are using Hibernate3, try out the SpecialOneToOneType. It was intended for exactly this purpose. It looks something like:



Basically, it is just another way to twist a many-to-one into a one-to-one.

humm, thanks. there's no workaround for for 2.1.8 ?

Hi steve,
Has second-level caching based on property-refs been implemented in 3.2.5.ga? (many-to-one)