NHibernate JoinQueryOver - nhibernate

Question

Calling all NHibernate gurus out there!
If any one of you brainy folks could help me with the following conundrum I'd be most grateful:
I have some entities that describe RSS feeds from various sources that are grouped together in an entity called FeedList.
I am trying to select only the distinct SourceFeed entities that are linked with a given FeedList. (i.e "WHERE FeedList.name = 'feedlist1' ".
I've been playing around with JoinQueryOver for a while now but I just can't seem to work out how to get the required results.
The entities are related like this:
FeedList > Feed > FeedSource
So a FeedList contains many Feeds and each Feed belongs to a FeedSource.
Here is the code for the entities:
public class Feed
{
public virtual int Id { get; set; }
public virtual string Description { get; set; }
public virtual FeedSource FeedSource { get; set; }
public virtual string URL { get; set; }
}
public class FeedList
{
public virtual int Id{get;set;}
public virtual string Name { get; set; }
public virtual IList<Feed> Feeds { get; set; }
}
public class FeedSource
{
public virtual int Id { get; set; }
public virtual string Name { get; set; }
}
I am using Fluent Automapping with the following overrides:
public class FeedOverride : IAutoMappingOverride<Feed>
{
public void Override(AutoMapping<Feed> mapping)
{
mapping.References<FeedSource>(map => map.FeedSource).Cascade.All();
}
}
public class FeedListOverride : IAutoMappingOverride<FeedList>
{
public void Override(AutoMapping<FeedList> mapping)
{
mapping.HasManyToMany<Feed> (map => map.Feeds).Cascade.All().Table("FeedList_Feed");
}
}
Here is some code that creates some sample data:
private static void CreateSampleData()
{
using (var session = HibernateHelper.OpenSession())
{
using (var transaction = session.BeginTransaction())
{
//Create source 1 and feeds
FeedSource source1 = new FeedSource() { Name = "BBC" };
IList<Feed> feedsForSource1 = new List<Feed>(){
CreateFeed("Sample Feed1",source1,"http://feed1.xml"),
CreateFeed("Sample Feed2",source1,"http://feed2.xml")
};
FeedList feedList1 = CreateFeedList("FeedList1", feedsForSource1);
//Create source 2 and feeds
FeedSource source2 = new FeedSource() { Name = "Sky" };
IList<Feed> feedsForSource2 = new List<Feed>(){
CreateFeed("Sample Feed3",source2,"http://feed3.xml"),
CreateFeed("Sample Feed4",source2,"http://feed4.xml"),
CreateFeed("Sample Feed5",source2,"http://feed5.xml")
};
FeedList feedList2 = CreateFeedList("FeedList2", feedsForSource2);
session.SaveOrUpdate(feedList1);
session.SaveOrUpdate(feedList2);
transaction.Commit();
}
}
}
What am I trying to achieve?
If I were to describe it (very poorly) in SQL, I'm looking to do something like this:
select distinct *
from FeedList as list
LEFT JOIN FeedList_Feed as list_feed
ON list.Id = list_feed.FeedList_id
LEFT JOIN Feed as feed
ON feed.FeedSource_id = list_feed.Feed_id
LEFT JOIN FeedSource as src
ON src.Id = list_feed.Feed_id
WHERE list.Name="a feedlist name"
Thanks very much for your time :)

Answer 1

Ok so I've managed to work this out finally for anyone that's interested:
Entities
public class Feed
{
public virtual int Id { get; set; }
public virtual string Description { get; set; }
public virtual FeedSource FeedSource { get; set; }
public virtual string URL { get; set; }
public virtual FeedList FeedList { get; set; }
}
public class FeedList
{
public virtual int Id{get;set;}
public virtual string Name { get; set; }
public virtual IList<Feed> Feeds { get; set; }
}
public class FeedSource
{
public virtual int Id { get; set; }
public virtual string Name { get; set; }
}
Overrides
public class FeedOverride : IAutoMappingOverride<Feed>
{
public void Override(AutoMapping<Feed> mapping)
{
mapping.References<FeedList>(map => map.FeedList).Cascade.All();
mapping.References<FeedSource>(map => map.FeedSource).Cascade.All();
}
}
public class FeedListOverride : IAutoMappingOverride<FeedList>
{
public void Override(AutoMapping<FeedList> mapping)
{
mapping.HasManyToMany<Feed>(map => map.Feeds).Cascade.All().Table("FeedList_Feed");
//mapping.HasMany<FeedListFeed>(map => map.Feeds).Cascade.All();
}
}
And finally:
The Query
session.QueryOver<FeedList>()
.Inner.JoinAlias(f => f.Feeds, () => feedAlias)
.Where(fl => fl.Name == name)
.Select(x => feedAlias.FeedSource)
.List<FeedSource>().Distinct().ToList();