domain driven design - NHibernate persist object changes for approval -

i building application allows users make changes objects, changes have approved before made permanent. using nhibernate.

how handle sort of scenario using? there articles out there tackle issue?

i thinking of having 2 tables each object. 1 current state , 1 proposed state. having generic changerequest object specify delete/insert/update , subject wants changed. but, don't believe nhibernate allow have 2 different mappings same object.

the 2 options off top of head...

each object have approved flag or approved date. (this encapsulated in common base class.) either need composite key including approval column (not recommended - composite keys pain) or each object have business key in addition pk. mean 1 table per entity metadata columns in each table determine approved. (you decide whether keep changes or latest.)

the other option 2 separate tables each object. can using entity names, introduced in nh2.1. easiest show example. have 1 class definition:

public class foo {     public virtual int id { get; set; }     public virtual string name { get; set; } } 

we have 2 hbm.xml files. note entity-name attribute after class. creates 2 tables, foo1 , foo2. (you pick own names via table attribute.)

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="nhhacking" assembly="nhhacking">   <class name="foo" entity-name="foo1">     <id name="id">       <generator class="native" />     </id>     <property name="name"/>   </class> </hibernate-mapping>  <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="nhhacking" assembly="nhhacking">   <class name="foo" entity-name="foo2">     <id name="id">       <generator class="native" />     </id>     <property name="name"/>   </class> </hibernate-mapping> 

when save entities, provide entity-name operation:

var foo1 = new foo {name = "foo1"}; var foo2 = new foo {name = "foo2"}; session.save("foo1", foo1); session.save("foo2", foo2); 

this allows select table entity goes to. of course want encapsulate entity names in constants class. need specify entity name operations (session.get(), session.save(), session.update(), session.delete(), etc.)