NHibernate QueryOver with MaxResult, Group By and Order By

Question

I'm trying to convert a SQL query to NHibernate QueryOver syntax, but I don't understand how to sort by the count projection.

This is what the SQL Query looks like:

select top 10 v.intVoteUserID, COUNT(v.intVoteUserID)
from Group_MessageVotes v
where v.dtmVote > :date
group by v.intVoteUserID
order by COUNT(v.intVoteUserID) desc

Any ideas?

Answer 1

You can simply repeat the projection in the OrderBy-clause.

The following query will give you an IList<object[]> where the first element of each item is the id and the second is the count.

var result = session.QueryOver<GroupMessageVotes>()
.Select(
    Projections.Group<GroupMessageVotes>(e => e.intVoteUserID),
    Projections.Count<GroupMessageVotes>(e => e.intVoteUserID)
    )
.OrderBy(Projections.Count<GroupMessageVotes>(e => e.intVoteUserID)).Desc
.Take(10)
.List<object[]>();