public class ParentMap : ClassMap<Parent>
{
    public ParentMap()
    {
        Table("parent_def");      
        Id(x => x.Id,"parent_id");
        Map(x => x.UID, "parent_uid").CustomSqlType("varchar").Length(40);
        Map(x => x.DeletedAt ,"dte_deleted").Nullable();
        Map(x => x.ModifiedAt, "dte_modified").Nullable();
        Map(x => x.CreatedAt, "dte_created").Nullable();
        Map(x => x.AutoUpdate, "auto_update").CustomSqlType("bit");
       
        HasMany(x => x.ParentVersions)
            .KeyColumn("parent_id")
            .Inverse()
            .Cascade.All();
    }
}
 
public class ParentVersionMap : ClassMap<ParentVersion>
{
    public ParentVersionMap()
    {
        Table("parent_version");
        ReadOnly();
 
        Id(x => x.Id  ,"parent_version_id");
        Version(x => x.Version)
            .Column("parent_version")
            .Generated.Never();
        Map(x => x.ParentHash ,"parent_hash")
            .CustomSqlType("varchar")
            .Length(40);
        Map(x => x.DateCreated ,"dte_created");
        Map(x => x.UpdateAvailable, "update_available");
 
        References(x => x.Parent, "parent_id")
            .ForeignKey("parent_id");
    }
}