LINQ to NHibernate WHERE EXISTS IN - nhibernate

Question

I've been trying out NHibernate 3 and LINQ to NHibernate. I can't get it to spit out the correct T-SQL query.
Here's my domain model:
Employee { id, name }
Department { id, name }
EmployeeDepartment { id, employee_id, department_id, startdate, enddate }
AttendanceRegistration { id, datetime, employee_id }
Now suppose I'd like to select all AttendanceRegistrations between '2010-10-1' and '2010-11-1' that were connected to a certain department at that time.
DateTime start = new DateTime(2010,10,1);
DateTime end = new DateTime(2010,11,1);
var list =
from ar in session.Query<AttendanceRegistration>()
where
start <= ar.datetime && ar.datetime > end && (
from ed in session.Query<EmployeeDepartment>()
where
ed.startdate <= ar.datetime && ed.enddate > ar.datetime &&
ed.department_id = 1
select ed.employee_id
).Contains(ar.employee_id)
select ar;
The resulting SQL Code will look like this:
select ar.id, ar.datetime, ar.employee_id
from AttendanceRegistration ar
where
'2010-10-1 00:00:00' <= ar.datetime and '2010-11-1' > ar.datetime and exists (
select ed.employee_id
from EmployeeDepartment ed
where
ed.department_id=1 and
ed.startdate <= ar.datetime and
ed.enddate > ar.datetime and
ed.id=ar.employee_id
)
This is ALMOST good :-) The only mistake is
ed.id=ar.employee_id
This should have been:
ed.employee_id=ar.employee_id
Does anybody have ideas how to get LINQ to NHibernate spit out the correct T-SQL query?

Answer 1

I ran into the same problem. I found a way to get around this. Your query can be rewritten as follows. Basically instead of using Contains() operator, add your predicate explicitly in the where clause and use Any() operator.
DateTime start = new DateTime(2010,10,1);
DateTime end = new DateTime(2010,11,1);
var list =
from ar in session.Query<AttendanceRegistration>()
where
start <= ar.datetime && ar.datetime > end && (
from ed in session.Query<EmployeeDepartment>()
where
ed.startdate <= ar.datetime && ed.enddate > ar.datetime &&
ed.department_id == 1
&& ed.employee_id == ar.employee_id
select ed
).Any()
select ar;