I'm trying to use the special property class in my hql query but it's saying

I'm getting the following error:

NHibernate.QueryException: could not resolve property:class of :eg.Domain.Track [select orderItem._ID from eg.Domain.Order.OrderItem as orderItem join orderItem.Product as track join track.Album as album where album.Artist._ID = 212 and orderItem.Product.class = 5]

the hql query is:

select orderItem._ID from OrderItem as orderItem
join orderItem.Product as track join track.Album as album where album.Artist._ID = 212 and track.class = 5

the mapping in OrderItem is:

<any name="Product"
meta-type="Int32"
id-type="Int32">
<meta-value class="eg.Domain.Track, eg.Domain" value="5"/>
<meta-value class="eg.Domain.Ringtone, eg.Domain" value="6"/>
<column name="item_type"/>
<column name="item_id"/>
</any>

can someone tell me what I've got wrong?

in HQL the class clause should be used to test the equality with a class name. in your case should be "... track.class=Track"
I still don't understand what strategy did you use for mapping the inheritance hierarchy.

cheers,
radu

I used a Table per Concrete class Hierarchy.

However even if I use the class name (which I'm not sure is correct if I'm using meta-values), I still get the same error.

Ahhh, I forgot to state polymorphism="implicit"

And just in case anyone else has this problem...

1. polymorphic joins don't work if the Table per Class Hierarchy inheritance strategy is used, so you need to do an old fashioned join in the where clause
2. Since it's joining in the where clause, the orderItem.Product.class may not be necessary (I haven't tried it without it yet)
3. if you are using meta-values, the poster above was wrong, you do specify the value, not the class

so, the final query which worked is:

select orderItem from
OrderItem as orderItem,
Track as track,
Album as album,
where orderItem.Product.class = 5
and orderItem.Product.id = track.id
and track.Album.id = album.id
and album.Artist.id = 212

well, I'm using the table per class inheritance mapping strategy and polymorphic joins do work, but I'm using the joined-subclass element to map the subclass. can you give an example of a polymorphic query which doesn't work, please? - i'm eager to understand hibernate limitations.
Anyway I've noticed that the class clause produces buggy SQL whith this inheritance mapping strategy - i'm preparing to file a bug report on jira.

cheers,
radu

sorry - i meant table per concrete class.