Thanks in advance for any tips or tricks for this issue!

I have an entity (Headline) which is described by Metadata. Metadata is implemented as a few different joined-sublcasses (Company, Publication, Region, etc..)

I've associated Metadata to Headlines through an associative entity (this is another issue altogether. Perhaps someone can suggest a better way to perform this association as it seems unweildy when it comes to writing HQL.)

What we're trying to do now is lookup Headlines that need to be removed. The condition for this purging is based on an attribute of Publication Metadata entities. But we can't figure out a way to filter a collection (Headline.metadata) for a specific type

e.g:

delete
from Headline hl
where hl.metadata.class = Publication pub
and pub.ttl > (sysdate - hl.published)

So this could be simplified by asking "Can one constrain a condition on a collection by subclass?" :-)

thanks!

(1) you can use a composite element instead of an entity (you should use Hibernate 2.1 though)

(2) Collection mappings have a where attribute

(3) You could use a collection filter

Gavin-

Composition isn't the way the model is built as metadata has a many-to-many relationship with Headlines. I assume the collection "where" attribute is subject to the same rules in HQL (unless I'm completely overlooking something here) in that there is no way to specify you only want a particular subclass of the associated entities (Publications are Metadata, and Headlines associate to Metadata.)

Would it be clearer to ask "how I can go from Headline to Publications in a single statement?"

(1) composite-elements are intended EXACTLY for many-to-many associations. Please read the documentation.


(2) The where attribute is an SQL fragment. Please read the documentation.