Hi all,

I read in the documentation that NHibernate is able to use some aggregate functions. But I have no clue how I can use them to fill a property of an DTO. Here's the problem:

We have some object tree structures, basically a kind of productgroup hirarchy. Now the guy who's in charge of this structure and the corresponding business processes came to me and gave me his "favorite" ;) SQL statement.

As you can imagine behind outlet_tree_id the whole outlet_tree DTO is "hidden". In the where clause outlet_tree_id=1 has to be parameterized.

So far I thought about using a named query in the XML mapping file. But I have no clue how I can fill a property with the level value. There is no corresponding column in the database therefore no information about this property is in the XML mapping file.
Any hints on filling the whole DTO with the additional field for the level value will be very appreciated. :)

Thanks in advance
Chavez

actually, you already have your answer. go ahead and create the named query in your mapping file. then create a method in your DTO:



there is a bug in this code in which the call to the List() method will return an IList instead of an int. there is a way to return a .UniqueResult() but i don't remember the proper usage off the top of my head.

you could also try to make this an immutable property:



but then you are relying on a private member variable m_treeId instead of a passed param. not sure if that works for you.

-devon

Hi devonl,

thanks for your reply. :)
The statement returns the whole tree with the given ID as root. So the value of the level property changes if you choose another object as root. If I implement the level as immutable object, as you suggested, every object as to be asked for his level before a new tree can be build. The other guy isn't very comfortable with this approach. I can see his concerns too.

I played a bit with some stuff and came to a couple of ideas and questions. Is it possible to tell NHibernate it has to populate all DTO properties and the additional property for the level in the particular case of this named query? Until now I only saw that NHibernate returns a "list of lists" as result of a a prepared query. Prepared query in this case means a query generated through the CreateQuery() method. It looks like this:

and so on...

To work with such a result I have to manually map every entry to a DTO or is there another way? Maybe I'm thinking in the wrong direction?!

Greetings,
Chavez