public SingleResult <Employee> Handle(EmployeeByUserNameQuery specification)
 {
     using (ISession session = DataContext.GetTransactedSession())
     {
         IQuery query = session.CreateQuery("from Employee emp where emp.UserName = :username");
         query.SetParameter("username", specification.UserName);
         var match = query.UniqueResult <Employee>();
         return(new SingleResult <Employee>(match));
     }
 }
        public SingleResult <Employee> Handle(EmployeeByUserNameQuery specification)
        {
            var employee = _context.Set <Employee>().SingleOrDefault(e => e.UserName == specification.UserName);

            return(new SingleResult <Employee>(employee));
        }