NHibernate auditing with Event listeners - how to create history object in IPreUpdateEventListener.OnPreUpdate

Question

I'm taking advantage of great article:

http://ayende.com/blog/3987/nhibernate-ipreupdateeventlistener-ipreinserteventlistener

and have implemented OnPreInsert exactly like in the example. However, my auditing requirement when updating the entity, is to create a "history" entry in database. Let's say:

• I fetch Person object

• I modify

  personObj.FirstName = Console.ReadLine();

• then I save the entity. Now, in IPreUpdateEventListener.OnPreUpdate I want to change UpdatedAt & UpdatedBy properties of Entity & State (just like in the article), and also I need to add a new record to database that contains old values (FirstName before change).

I saw that PreUpdateEvent contains OldState array, however I have no idea how to create a Person object fron OldState array and save it.

How can I achieve what I need?

Thanks!

Answer 1

however I have no idea how to create a Person object fron OldState array and save it.

Have you had a look at NHibernate Envers? It does just that.

If you don't want to use this framework for some reason, take a look at its source code.