Hi Gavin,


Are you planing to support subclass element inside joined-subclass ?.
From DTD I can see that it's not supported.
Thanks.

Giedrius

Hi,

This is a feature that I'm also interested in; specifically, putting "subclass" inside "joined-subclass". It seems that if you put the "discriminator" tag in a joined-subclass, and then put subclasses in, it seems to read fine -- but the whole thing dies at runtime (database constraint).

It would seem logical to me that you should be able to put discriminators in joined-subclasses (without the need for a special "join" tag; seen in another thread) -- especially if you don't want to mix the two beyond that, e.g.:



This is pretty much exactly what I need to do for the application I'm building. Obviously this is open source, so I guess I should get in there and add it. However, if there's some alternative on the roadmap, I'd be interested to know. It's really just a performance/storage optimization, more than anything else -- not a priority at this stage.

Simon.

The roadmap includes the <join> element, which could be used to do this.

Would you be able to think up a quick example of how this would work?

Thanks

Simon.

there is an exampe ON the roadmap!

Thanks for the pointer... That does look like it would be a useful tag.

It seems to be able to introduce extra tables -- however, I'm trying to reduce the number of tables/updates. For example, parent classes with all the attributes, and child classes introducing nothing new other than logic -- these don't really need their own tables, since they contain nothing other than IDs. So the best thing is to put a discriminator type thing in the parent class definition. Which works, as long as the parent classes isn't a joined-class inside another class (or another joined-class).

Is there a way to refactor the example I gave above to use the <join> tag?

Thanks

Simon.

AH, ok, if thats what you want then no, there is nothing planned. The <join> feature would only help if you had a discriminator on the top-level table.

You would need a new persister for this kind of thing.

I'd be interested in contributing this, but would need a place to start. Would it be easy to combine the discriminator logic for the <class> and <joined-subclass> tags?

Simon.

No it would certainly not be easy. Try something smaller to start off with.

PS. The relevant code is EntityPersister/NormalizedEntityPersister

Thanks, I'll at least have a look at it. I'm sure it's a feature that at least a few people would appreciate, so it's probably worth investigating.

Regards

Simon.