Question

I have this piece of code in a TaskRepository :

public List<Task> GetActiveTasks()
    {

        return SessionContainer.Session
            .Query<Task>()
            .Where(t => t.IsActive())
            .ToList();
    }

And this is the IsActive() method in the Task Class

public virtual bool IsActive()                                 
{
 return States.ToList().Max().Name == "Active";
}

My problem is that GetActiveTasks() returns NotSupportedException.

Does anyone knows whats the problem ? I think it is not possible to call instance methods in the Where predicate. If that is not possible, is there any workaround for this? I need to get all the active tasks but I dont know how to do it if it is not like this.

Answer 1

The lambdas given in the Query have to be translated to sql. How should NHibernate interprete a method implemented by you? it can’t. However you could map IsActive as a Formula property and query that. Something like:

Map(x => x.IsActive).Formula("(SELECT ... FROM (Select s.Name FROM States s WHERE s.task_id = Id ORDER BY Id desc LIMIT 1) maxState WHERE maxState.Name == Active)")