Question

Having a really hard time trying to figure out a “where in” equivalent in nHibernate.

I am using nHibernate 3. What’s the best way to do something like this:

SELECT DISTINCT                                     
    U.ID as CID                         
FROM User U
WHERE                                               
CID IN (                                            
    SELECT RID                                      
    FROM ResellerSites rs                           
    INNER JOIN Locations l ON l.ID = rs.LID         
    WHERE   l.ID        =   14          
) 

I found an examples somewhere that says I need to have something like this:

var criteria = session.CreateCriteria(typeof(User));

var resellerSites = new[] { new ResellerSite { Id = 1 }, new ResellerSite { Id = 2 } };
criteria.Add(new InExpression("ResellerSite", resellerSites));

This is what I have so far:

     var resellerSites = session.CreateCriteria<ResellerSite>("p")
                        .CreateCriteria("p.Locations", JoinType.InnerJoin)
                        .Add(Restrictions.Eq("locationID", locationId))
                        .List<ResellerSite>();

     criteria.Add(new InExpression("ResellerSite", resellerSites));

     var finalList = criteria.List<ResellerSite>();

The “criteria.Add(new InExpression” part is giving me an intellisense error, as InExpression seems to expect something like:

 new[] { new ResellerSite { Id = 1 }, new ResellerSite { Id = 2 } };

Like in the first example.

Should I do a for loop like:

foreach (var site in resellerSites)
{
    //somehow push into a  new[] ?
}

or something like that or is there a better way?

Perhaps this entire approach is wrong?

Answer 1

I’d say that the typing problem comes from the double CreateCriteria and the single ToList()

Difficult to say without the table definitions, but, rereading you code, I wonder why you need the inner join with the locations.
May be you can rewrite your query as :

SELECT DISTINCT                                     
    U.ID as CID                         
FROM User U 
    INNER JOIN ResellerSites rs
       on U.ID = rs.RID
       and rs.LID=14

And have your code like (not tested and not optimal as you could have only one criteria query with join)

var resellerSites = session.CreateCriteria<ResellerSite>()
                    .Add(Expression.Eq("locationID", locationId))
                    .List<ResellerSite>();

 criteria.Add(new InExpression("ResellerSite", resellerSites.ToArray()));

 var finalList = criteria.List<ResellerSite>();