[nhibernate-issues] [NHJIRA] Created: (NH-2705) Linq/Hql/Criteria Fetch on class hierarchy generates invalid SQL when derivees mix component and many-to-one mappings

[Andrei A. (JIRA) <nh...@gm...>]

Linq/Hql/Criteria Fetch on class hierarchy generates invalid SQL when derivees mix component and many-to-one mappings
---------------------------------------------------------------------------------------------------------------------

                 Key: NH-2705
                 URL: http://216.121.112.228/browse/NH-2705
             Project:  NHibernate
          Issue Type: Bug
          Components: Core
    Affects Versions: 3.1.0
            Reporter: Andrei Alecu
            Priority: Major


Consider the following scenario:

    public class ItemBase
    {
        public virtual int Id { get; set; }
        public virtual SubItemBase SubItem { get; set; }
    }

    public class ItemWithComponentSubItem:ItemBase { }
    
    public class ItemWithManyToOneSubItem:ItemBase { }

ItemWithComponentSubItem defines in its mapping that SubItem is a component of SubItemComponent type (which derives from SubItemBase)
ItemWithManyToOneSubItem defines in its mapping that SubItem is a many-to-one of SubItemEntity type (again, derives from SubItemBase)

Running the following query with fetch results in invalid SQL being executed:

     from ItemBase i left join fetch i.SubItem

Removing the fetch makes it work properly.

     from ItemBase i

Also, this works:
     from ItemWithManyToOneSubItem i left join fetch i.SubItem

But this doesn't:
     from ItemWithComponentSubItem i left join fetch i.SubItem (one would argue there's nothing to fetch here, but instead of throwing an exception, the fetch instruction should just be ignored and maybe a warning logged, it would allow for much better reuse of code)

I will attach a unit test that demonstrates this bug, and also a related one at NH-2615.

I believe the correct behavior here is to allow fetch on components, and simply ignore it rather than throwing an exception.

-- 
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators: http://216.121.112.228/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira