I have a problem with NHibernate, I can't seem to find any solution for.
In my project I have a simple entity (Batch), but whenever I try and run the following test, I get an exception.
I've triede a couple of different ways to perform a similar query, but almost identical exception for all (it differs in which LINQ method being executed).
The first test:
[Test]
public void QueryLatestBatch()
{
using (var session = SessionManager.OpenSession())
{
var batch = session.Query<Batch>()
.FirstOrDefault();
Assert.That(batch, Is.Not.Null);
}
}
The exception:
System.NullReferenceException : Object reference not set to an instance of an object.
at NHibernate.Linq.NhQueryProvider.PrepareQuery(Expression expression, ref IQuery query, ref NhLinqExpression nhQuery)
at NHibernate.Linq.NhQueryProvider.Execute(Expression expression)
at System.Linq.Queryable.FirstOrDefault(IQueryable`1 source)
The second test:
[Test]
public void QueryLatestBatch2()
{
using (var session = SessionManager.OpenSession())
{
var batch = session.Query<Batch>()
.OrderBy(x => x.Executed)
.Take(1)
.SingleOrDefault();
Assert.That(batch, Is.Not.Null);
}
}
The exception:
System.NullReferenceException : Object reference not set to an instance of an object.
at NHibernate.Linq.NhQueryProvider.PrepareQuery(Expression expression, ref IQuery query, ref NhLinqExpression nhQuery)
at NHibernate.Linq.NhQueryProvider.Execute(Expression expression)
at System.Linq.Queryable.SingleOrDefault(IQueryable`1 source)
However, this one is passing (using QueryOver<):
[Test]
public void QueryOverLatestBatch()
{
using (var session = SessionManager.OpenSession())
{
var batch = session.QueryOver<Batch>()
.OrderBy(x => x.Executed).Asc
.Take(1)
.SingleOrDefault();
Assert.That(batch, Is.Not.Null);
Assert.That(batch.Executed, Is.LessThan(DateTime.Now));
}
}
Using the QueryOver< API is not bad at all, but I'm just kind of baffled that the Query< API isn't working, which is kind of sad, since the First() operation is very concise, and our developers really enjoy LINQ.
I really hope there is a solution to this, as it seems strange if these methods are failing such a simple test.
EDIT
I'm using Oracle 11g, my mappings are done with FluentNHibernate registered through Castle Windsor with the NHibernate Facility.
As I wrote, the odd thing is that the query works perfectly with the QueryOver< API, but not through LINQ.
