If I'm not mistaken, the Formula is SQL based, not HQL, so HQL won't work in
a formula.
Everything looks correct, what do you get back in the model as a result of
that formula? In your original email it was cut off before you said what the
post count was always... If I get a chance tonight I'll try and recreate
your scenario and see if it can't be determined what's up.
One disadvantage to doing the post count this way that I can see: In the
domain model, if you add another post count to the collection, before
persisting, I don't believe your post count property will reflect that.
You'd have to save the collection first back to the database, then retrieve
the Topic object again in another session. At least, I'm pretty sure that's
how it'll work and can find out for sure if I recreate the scenario.
Another (third option) from even doing a read only formula, is to get the
best of all worlds, and that is to map an int column, without it being a
formula. It's just a standard int.
Then create an Add/Remove Post method to manipulate the collection of Posts.
Every time you Add or Remove a post, in your method, you increment/decrease
the post count after manipulating the collection. Now that property is just
a property to map back to the database, you can lazyload the collection, and
you can get the count without having to load the entire list of posts, and
the count will be updated during domain model manipulation in a session,
before you persist back to the database.
On Tue, Oct 13, 2009 at 6:15 AM, Schlaefisch <schlaefi...@googlemail.com>wrote:
>
> Session.CreateQuery("select count(*) from Post p WHERE p.Topic.Id=" +
> topic.Id)
>
> works fine, but
>
> mapping.Map(t => t.PostCount).Formula("(select count(*) from Post p
> WHERE p.Topic.Id = Id)");
>
> results in an SqlException (Invalid object name 'Post')
>
>
> On Oct 13, 12:49 pm, Mikael Henriksson <mik...@zoolutions.se> wrote:
> > I know exactly what you mean. It just feels wrong having to load the list
> to
> > get the count.Have you tried with HQL?
> >
> > On Tue, Oct 13, 2009 at 12:43 PM, Schlaefisch <
> schlaefi...@googlemail.com>wrote:
> >
> >
> >
> > > No, the posts are not a child collection of the topic to avoid
> > > performance issues. I don't want to load all posts of all topic just
> > > to get the post count.
> >
> > > On Oct 12, 3:14 pm, Hudson Akridge <hudson.akri...@gmail.com> wrote:
> > > > Are posts a child collection on your object being mapped? I ask,
> because
> > > > there might be an alternative to getting you that number. If you map
> a
> > > > Posts.Count() to a property, then map that with a read only accessor,
> it
> > > > should give you a similar solution.
> >
> > > > On Mon, Oct 12, 2009 at 6:41 AM, Paul Batum <paul.ba...@gmail.com>
> > > wrote:
> > > > > Can you post your domain object and the mapping override for it?
> > > > > I figure something else has to be screwing up the result of the
> > > formula.
> >
> > > > > On Mon, Oct 12, 2009 at 4:06 PM, Schlaefisch <
> > > schlaefi...@googlemail.com>wrote:
> >
> > > > >> The exact query results in a syntax error, when I replace
> "this_.Id =
> > > > >> @p0;@p0 = 1" with "this_.Id = 1" the result is correct.
> >
> > > > >> But even when I use "SELECT 5" as formula, the PostCount is still
> 0.
> >
> > > > >> On Oct 6, 1:16 pm, Paul Batum <paul.ba...@gmail.com> wrote:
> > > > >> > Off the top of my head, I can't see anything wrong with your
> > > mapping.
> > > > >> I've
> > > > >> > used formula columns with automapping for similar purposes
> without
> > > > >> problems.
> > > > >> > Have you executed that generated query against the db and
> confirmed
> > > that
> > > > >> it
> > > > >> > returned the correct results?
> >
> > > > >> > On Fri, Oct 2, 2009 at 9:06 AM, Schlaefisch <
> > > schlaefi...@googlemail.com
> > > > >> >wrote:
> >
> > > > >> > > Update: The Console Output.
> >
> > > > >> > > Manual SQL:
> > > > >> > > NHibernate: (SELECT COUNT(*) FROM forumPosts p where p.TopicID
> =
> > > 1)
> > > > >> > > Mapping SQL:
> > > > >> > > NHibernate: SELECT top 2 this_.Id as Id0_0_, this_.Title as
> > > Title0_0_,
> > > > >> > > this_.Created as Created0_0_, this_.DisplayPriority as
> > > DisplayP4_0_0_,
> > > > >> > > this_.ForumID as ForumID0_0_, (SELECT COUNT(*) FROM forumPosts
> p
> > > where
> > > > >> > > p.TopicID = this_.Id) as formula0_0_ FROM forumTopics this_
> WHERE
> > > > >> > > this_.Id = @p0;@p0 = 1
> >
> > > > --
> > > > - Hudsonhttp://www.bestguesstheory.comhttp://
> twitter.com/HudsonAkridge
> >
>
--
- Hudson
http://www.bestguesstheory.com
http://twitter.com/HudsonAkridge
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