Question

I’m trying to get an object back from an NHibernate query.

My method is as follows:

public Site GetSiteByHost(string host)
{
    var result = _session.CreateCriteria<Site>()
        .Add(SqlExpression.Like<Site>(g => g.URLName, host));

    return result;
}

the problem is, result is a type of HNibernate.ICriteria.

How can I get this to return a Site object?

If I was doing this with LINQ to SQL it’d be something like .FirstOrDefault() but that’s not available with NHibernate… or is it?!?!

Answer 1

You need to first execute the query (by calling List<T>() on the criteria) before calling FirstOrDefault. Notice that this query might return multiple objects:

IEnumerable<Site> sites = _session
    .CreateCriteria<Site>()
    .Add(SqlExpression.Like<Site>(g => g.URLName, host))
    .List<Site>();

And you could take the first one:

Site result = sites.FirstOrDefault();

or directly:

public Site GetSiteByHost(string host)
{
    return _session
        .CreateCriteria<Site>()
        .Add(SqlExpression.Like<Site>(g => g.URLName, host))
        .List<Site>()
        .FirstOrDefault();
}