HQL to CriteriaQuery when using bitwise operators - nhibernate

Question

How do I convert this into a CriteraQuery:
select n
from TagRegistration t
join t.Tag n
where t.Status & :status > 0
order by count(t.ID) desc
, n.Name asc

Answer 1

Here's how you could do it with the criteria API:
[Flags]
enum Bar{
A = 0x01,
B = 0x02,
C = 0x04
}
var criteria = this.Session.CreateCriteria<Foo>()
.Add( BitwiseFlags.IsSet( "Bar", Bar.A | Bar.C ) );
using:
public class BitwiseFlags : LogicalExpression
{
private BitwiseFlags( string propertyName, object value, string op ) :
base( new SimpleExpression( propertyName, value, op ),
Expression.Sql( "?", value, NHibernateUtil.Enum( value.GetType() ) ) )
{
}
protected override string Op
{
get { return "="; }
}
public static BitwiseFlags IsSet(string propertyName, Enum flags)
{
return new BitwiseFlags( propertyName, flags, " & " );
}
}
should generate the following output where clause:
FROM _TABLE
WHERE (this_.Bar & 5 = 5)
which should give you rows that have flags Bar.A and Bar.C set (excluding everything else). You should be able to use it with conjunction and disjunction too.

Answer 2

Did something like that a while ago.
Try something like this.
PropertyProjection projection = Projections.Property("t.ID");
PropertyProjection property = Projections.Property("n.Namn");
ICriteria criteria = session.CreateCriteria<TagRegistration>("t")
.CreateCriteria("Tag","n")
.Add(
Restrictions.Gt(
Projections.SqlProjection("({alias}.ID & 3) as bitWiseResult", new[] { "bitWiseResult" }, new IType[] { NHibernateUtil.Int32 })
, 0)
)
.AddOrder(Order.Desc(Projections.Count(projection)))
.AddOrder(Order.Asc(property))
.SetProjection(Projections.GroupProperty(projection), Projections.GroupProperty(property))
Note this part {alias}.ID & 3) where I inserted the value directly which isn't very good but it works :)
You could do it better if you look at the test project of NHibernate
Nhibernate/Criteria/AddNumberProjection.cs
But you need to do a subQuery to return fully initialized Tag
I think this query is better to do in Hql.
Regards