Yes you are right I could get it from the collection's size but it's
obviously inefficient.
I'm not sure I want to create another value object for this though,
but supposing I did, I don't really understand the code you gave me
(sorry :(
You have declared a property number_of_posts which is never used
later. I think there's something wrong here :)
On 13 mai, 15:02, Jason Meckley <jasonmeck...@gmail.com> wrote:
> I would removed the countPosts property from the Source entity. If the
> entity needs the count it can be retrieved from the post list
> directly.
>
> class Source
> {
> IList<Post> Posts;
> int countPosts { get {return Posts.Count; } }
>
> }
>
> however this would be inefficient for your current projection. For
> that I would create a new value object
> class SourceWithPostCount
> {
> Source source {get;set;}
> int number_of_posts{get;set;}
>
> }
>
> and use a projection. Something like this. although I'm not 100% sure
> how to group by an entity, if at all. i actually have a thread open
> about this concept.
>
> var dtos = session
> .CreateCriteria<Source>()
> .SetProjection(
> Projections.List()
> .Add(Projections.GroupProperty("this"))
> .Add(Projections.Count("Posts")) // or .Add
> (Projections.Count(Projections.Property("Posts")))
> )
> .SetMaxResults(100)
> .SetResultTransformer([can't remember the exact transformer])
> .List<SourceWithPostCount>();
>
> On May 13, 9:20 am, graphicsxp <graphic...@googlemail.com> wrote:
>
> > Thanks for clarifying that ! The .List() in the doc was a bit
> > confusing and it makes more sense with UniqueResult<int> as you said.
>
> > So in my example, how could I use aggregation to fill in the countPost
> > property ? Is it possible at all, or can aggregate functions only be
> > used for returning a value, as opposed to setting a property ?
>
> > On 13 mai, 13:37, Jason Meckley <jasonmeck...@gmail.com> wrote:
>
> > > the example above will return the number of cats that are black. it's
> > > similar to the sql
> > > select count(*) from cat where color = 'black'
> > > in the sample projection you could change List() to UniqueResult<int>
> > > ()
>
> > > here is the difference between count and distinct count
>
> > > Sample Data:
> > > ID
> > > 1
> > > 1
> > > 2
> > > 3
> > > 4
> > > 4
> > > 4
>
> > > Count() will return 7 (1, 1, 2, 3, 4, 4, 4)
> > > DistinctCount() will return 4 (1, 2, 3, 4)
>
> > > On May 13, 5:01 am, graphicsxp <graphic...@googlemail.com> wrote:
>
> > > > Thanks zoid,
> > > > I actually had a look already at Projections but I don't really
> > > > understand how they work. For instance in the documentation :
>
> > > > IList results = session.CreateCriteria(typeof(Cat))
> > > > .SetProjection( Projections.RowCount() )
> > > > .Add( Expression.Eq("Color", Color.BLACK) )
> > > > .List();
>
> > > > There's no explanations about what this is supposed to return....
>
> > > > That said, even though I don't understand it, I have a feeling this is
> > > > not the correct projection for my problem. There is a Count() and
> > > > DistinctCount(), but again, I have no idea how to use them and there's
> > > > very little doc about this.
>
> > > > On 12 mai, 23:18, zoid <zoidb...@googlemail.com> wrote:
>
> > > > > Try Projections.
>
> > > > >http://nhforge.org/doc/nh/en/index.html#querycriteria-projection
>
> > > > > On May 12, 3:56 pm, graphicsxp <graphic...@googlemail.com> wrote:
>
> > > > > > Hello,
>
> > > > > > I'd like to get some help with a HQL syntax. Here are my classes :
>
> > > > > > class Post
> > > > > > {
> > > > > > Source theSource ;
>
> > > > > > }
>
> > > > > > class Source
> > > > > > {
> > > > > > IList<Post> Posts;
>
> > > > > > }
>
> > > > > > In the mapping of Source I have :
>
> > > > > > <bag name="Posts" lazy="true">
> > > > > > <key column="SourceID" />
> > > > > > <one-to-many class="Post"/>
> > > > > > </bag>
>
> > > > > > and in the mapping of Post I have :
>
> > > > > > <many-to-one class="Source" name="theSource" cascade="all-delete-
> > > > > > orphan" column="SourceID" />
>
> > > > > > Now what I want is to get a list of all the source entities that are
> > > > > > used by all the post entities created in a given date range :
>
> > > > > > ICriteria sourceCriteria = SessionManager.GetCurrentSession
> > > > > > ().CreateCriteria(typeof (Source));
>
> > > > > > sourceCriteria.CreateCriteria("Posts")
> > > > > > .Add(Restrictions.Lt("DateCreated",
> > > > > > DateTime.Parse(parameter.Attribute
> > > > > > ("enddate").Value)))
> > > > > > .Add(Restrictions.Gt("DateCreated",
> > > > > > DateTime.Parse(parameter.Attribute
> > > > > > ("startdate").Value)));
>
> > > > > > //make sure we get distinct Source
> > > > > > sourceCriteria.SetResultTransformer(new
> > > > > > DistinctRootEntityResultTransformer());
>
> > > > > > return sourceCriteria.SetMaxResults(100).List<Source>();
>
> > > > > > That works fine. Now let's change the Source class slightly :
>
> > > > > > class Source
> > > > > > {
> > > > > > IList<Post> Posts;
> > > > > > int countPosts;
>
> > > > > > }
>
> > > > > > I still don't want to load the Posts list (you've noticed that I
> > > > > > used
> > > > > > lazy-loading), however I would like my query to fill in the
> > > > > > countPosts
> > > > > > property with the number of Posts using each publication.
>
> > > > > > How do I do that using the above HQL ?
>
> > > > > > Thanks
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"nhusers" group.
To post to this group, send email to nhusers@googlegroups.com
To unsubscribe from this group, send email to
nhusers+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/nhusers?hl=en
-~----------~----~----~----~------~----~------~--~---
