Does NHibernate LINQ support ToLower() in Where() clauses?

Question

I have an entity and its mapping:

public class Test
{
    public virtual int Id { get; set; }
    public virtual string Name { get; set; }
    public virtual string Description { get; set; }
}

public class TestMap : EntityMap<Test>
{
    public TestMap()
    {
        Id(x => x.Id);
        Map(x => x.Name);
        Map(x => x.Description);
    }
}

I'm trying to run a query on it (to grab it out of the database):

var keyword = "test" // this is coming in from the user
keyword = keyword.ToLower(); // convert it to all lower-case

var results = session.Linq<Test>
    .Where(x => x.Name.ToLower().Contains(keyword));

results.Count(); // execute the query

However, whenever I run this query, I get the following exception:

Index was out of range. Must be non-negative and less than the size of the
collection. Parameter name: index

Am I right when I say that, currently, Linq to NHibernate does not support ToLower()? And if so, is there an alternative that allows me to search for a string in the middle of another string that Linq to NHibernate is compatible with? For example, if the user searches for kap, I need it to match Kapiolani, Makapuu, and Lapkap.

Answer 1

There seems to be a lot of confusion around this subject.

• The "old" Linq provider (for NHibernate 2.x) probably might not support this. If that's the case, it never will because it's not maintained anymore.
• The new provider (included with NHibernate 3.x) does support it (although ToUpper and ToLower seem to be inverted, see http://groups.google.com/group/nhibernate-development/browse_thread/thread/a167216e466b3241)
• Contains and StartsWith map to the LIKE operator in SQL. They are not case insensitive themselves; it's the collation that makes them case insensitive, so that depends on how your column/schema were created.

Update (2010-04-09): bug confirmed and patch submitted, see https://nhibernate.jira.com/browse/NH-2169

Update (2010-05-21): patch was applied on 2010-05-01 and works as expected now.