NHibernate QueryOver投影，枚举和aliastobean变换器

Question

How do I transform an Enum value into a String Value using QueryOver and AliasToBean? I have the following but get an error when trying to transform the Enum:

        SomeDTO someDTO = null;
        SomeReferenceAlias someReferenceAlias = null;
        var jobs = query
            .JoinAlias(x => x.SomeReference, () => someReferenceAlias, JoinType.InnerJoin)
            .SelectList(list => list
                .Select(p => p.SomeStatusEnum).WithAlias(() => someDTO.SomeStatus)//problem here
                .Select(p => someReferenceAlias.Name).WithAlias(() => someDTO.Name)
                )
            .TransformUsing(Transformers.AliasToBean<SomeDTO>())
            .Take(100)
            .List<SomeDTO>();

Answer 1

Assuming your enum is stored as int in your DB, I would try a string readonly property to a custom string type :

public enum SomeStatus {up=1,right=2,down=3,left=4}


public class SomeStatusNhString : NHibernate.Type.AbstractStringType
{
    public SomeStatusNhString()
          : base(new StringSqlType())
       {
       }

    public SomeStatusNhString(StringSqlType sqlType)
          : base(sqlType)
       {
       }

    public override string Name
    {
        get { return "SomeStatusNhString"; }
    }

    public override object Get(System.Data.IDataReader rs, int index)
    {
        var x = base.Get(rs, index);
        return ((SomeStatus)int.Parse((string)x)).ToString();
    }
}

And then your mapping

public virtual String StatusAsString{ get; set; }


<property name="StatusAsString" column="YOUR_COLUMN" not-null="true" insert="false" update="false" type="YourNameSpace.SomeStatusNhString, YourDll" access="property"></property>

Hope this can help