Error while conversion of Nhibernate query to generic list

Question

I have a simple entity called EmployeeEntity with properties ID, Name, Age, Organisation, and Designat

Answer 1

If you only want a certain set of columns, create a class that maps one to one with your columns. Like so:

public class EmployeeView
{
    public string Name { get; set; }
    public string Designation { get; set; }
    public int Age { get; set; }
    public string Organization { get; set; }
}

You then just need to add a result transformer to your query

IQuery query = session
    .CreateQuery("select Name ,Designation ,Age ,Organisation  FROM EmployeeEntity   group by  Name ,Designation ,Age ,Organisation")
    .SetResultTransformer(Transformers.AliasToBean<EmployeeView>());

Ilist<EmployeeEntity> employee= query.List<EmployeeView>();

Answer 2

When you're querying with select Name, Designation, Age, Organisation..., NHibernate will actually return an IList<object[]> instance. To overcome this, try rewriting your HQL to select new EmployeeEntity(Name, Designation, Age, Organisation)... and add an appropriate constructor to EmployeeEntity class.