nhibernate - QueryOver and null check on optional reference -

i have user 1-1 relation optional userdata. sharing same identifier in db.

user  id(x => id, "id")  references<userdata>(x => x.userdata, "id");  userdata  id(x => id, "id") 

i query users no optional data. query makes null check on user id column.

var list = session.queryover<user>()    .where(x => x.userdata != null) 

this case if use hasone.

assuming mapping :

    public class usermap : classmap<user>     {         public usermap()         {             table("usertable");             id(x=>x.id).column("id");             hasone(x => x.data);         }     }      public class userdatamap : classmap<userdata>     {         public userdatamap()         {             table("userdatatable");             id(x => x.id).column("id");             map(x=>x.datatext).column("datatext");          }     } 

you may try :

        userdata userdataalias = null;          var results = session.queryover<user>()             .left.joinqueryover(x=>x.data,()=>userdataalias)             .whererestrictionon(y=>y.id).isnull             .list(); 

the resulting query left outer join , is null clause following :

select         this_.id id14_1_,         userdataal1_.id id13_0_,         userdataal1_.datatext datatext13_0_              usertable this_      left outer join         userdatatable userdataal1_              on this_.id=userdataal1_.id              userdataal1_.id null