nhibernate - Mapping object id as int idententity -

i have domain objects in fluentnhibernate have id's of type object int (reasoning further below). right have sqlite end. want map id auto-increment. far have:

public class usermap : classmap<user> {     public usermap()     {         table("users");         id(x => x.id).customtype<int>().generatedby.native();         map(x => x.email);     } }  public class user {     public virtual object id { get; set; }     public virtual string email { get; set; } } 

but when maps being loaded throws fluentconfigurationexception message identity type must integral (int, long, uint, ulong) user.id property (stack trace says happens when call native. again, want auto-increment integer.

reasoning object id

we have business requirement support several rdbms's mongodb. aware bad idea, please focus on question. mongo uses objectid (a guid-like consecutive value type) it's default id type. idea hide actual id type (because it's data-layer dependent), reuse models , have 2 different data access implementations (mongo & nhibernate).

i ended fixing problem doing

id(x => x.id).customtype<int>()     .generatedby.custom<global::nhibernate.id.identitygenerator>()     .unsavedvalue(null); 

for reason, fluent nhibernate doesn't understand .customtype<int>() means int. had add custom generator bypass fluent's logic.

this fixes immediate problem, still need figure out how collections & foreign keys need work.