Question

Here is a simple example scenario –

A ‘Tag’ has many ‘Questions’. When I get a list of Tags how do I order by the Tags Question Count using the Criteria API?

I have done this before but haven’t touched NH in about 4 months and have forgotten… projections maybe? help!!!

Thanks

Answer 1

Sat down with a fresh pair of eyes and figured it out… Tags are now ordered by a propery on the Tags Question collection (views).. which made alot more sence in my domain than ordering by the count of children

    public IList<Tag> GetTop(int numberOfTags)
    {
        using (ITransaction transaction = Session.BeginTransaction())
        {

            DetachedCriteria detachedCriteria = DetachedCriteria.For<Tag>()
                    .CreateCriteria<Tag>(x => x.Questions)
                    .AddOrder<Question>(x => x.Views, Order.Desc)
                    .SetMaxResults(numberOfTags)
                    .SetProjection(Projections.Distinct(Projections.Id()));

            IList<Tag> tags = Session.CreateCriteria<Tag>()
                .SetFetchMode<Tag>(x => x.Questions,FetchMode.Join)
                .Add(LambdaSubquery.Property<Tag>(x => x.Id).In(detachedCriteria))
                .SetResultTransformer(new DistinctRootEntityResultTransformer())
                .List<Tag>();

            transaction.Commit();
            return tags;
        }
    }