map table to itself in Parent-Child relationship Fluent Nhibernate -

i have situation mapping table's columns primary key of same table. table looks this

---+-------+--------- id  name    parentid ---+-------+--------- 1   parent1  0 2   child 1  1 3   child 2  1 4   parent2  0 5   child 3  4 

i have created following model , fluent nhibernate mapping class

//model.locationtype.cs public class locationtype     {         public virtual long id { get; set; }         public virtual string shortname { get; set; }         public virtual string description { get; set; }                 public virtual ilist<locationtype> parentid { get; set; }     } 

and

//mapping.locationtypemap.cs public class locationtypemap : classmap<locationtype>     {         public locationtypemap()         {             table("set_loc_type");             id(x => x.id).column("loc_type_id").generatedby.assigned();             map(x => x.shortname, "short_name").length(15).not.nullable();             map(x => x.description, "loc_desc").length(50).not.nullable();             references(x => x.parentid).column("parent_loc_type_id").cascade.saveupdate();         }     } 

but receiving follow error message when execute code:

unable cast object of type 'smarthrms.core.domain.model.locationtype' type 'system.collections.generic.ilist`1[smarthrms.core.domain.model.locationtype]'.  

edit 1: instead of using tried

hasmany(x => x.parentids).keycolumn("parent_loc_type_id"); 

although worked , solved casting problem mentioned above result gettting reverse of need. in parent's locationtype objects, lists childs in ilist, above example result be:

-----+----------+------ id     name       parentid -----+----------+------ 1     parent1     ilist<child1, child2> 2     child 2     ilist<empty> 3 .... same 4     parent2     ilist<child3> 5     child 3     ilist<empty> 

seems should use hasmany in mapping instead of references.