How to Soft Delete with Nhibernate event listener ?

1. First, we need to define the domain specific interface ISoftDeletable to implement on the entities for which we need to keep a permanent record.

public interface ISoftDeletable
{       
      DateTime? DateDelete { set; get; }       
}

2. Next, we should create the SoftDeleteEventListener class that inherit from NHibernate.Event.Default.DefaultDeleteEventListener, and simply override the DeleteEntity method.

public class SoftDeleteEventListener : DefaultDeleteEventListener
{
  protected override void DeleteEntity(IEventSource session, object entity,
    EntityEntry entityEntry, bool isCascadeDeleteEnabled,
    IEntityPersister persister, ISet transientEntities)
  {
    if (entity is ISoftDeletable)
    {
      var e = (ISoftDeletable)entity;
      e.DateDelete = DateTime.Now;

      //CascadeBeforeDelete(session, persister, entity, entityEntry,            transientEntities);
      //CascadeAfterDelete(session, persister, entity, transientEntities);
    }
    else
    {
      base.DeleteEntity(session, entity, entityEntry, isCascadeDeleteEnabled,
                persister, transientEntities);
    }
  }
}

3. Finally, we need to configure the listener with nhibernate :

Nhibernate.cfg.Configuration configuration = new Configuration().Configure();
configuration.SetListener(ListenerType.Delete, new SoftDeleteEventListener());
configuration.BuildSessionFactory();

4. Now, to hide a deleted data, we define a soft delete filter in mapping file for which we need to keep a permanent record :

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" ...>
  <class ...>
    …
     <property name="DateDelete" column="DateDelete" type="DateTime" />  
     <filter name="SoftDeleteFilter"> </filter>
  </class>  
  <filter-def name="SoftDeleteFilter" condition="DateDelete IS NULL">
  </filter-def>    
</hibernate-mapping>

5. and, in the application_beginrequest, you should enable soft delete filter on the nhibernate session :

   nhibernateSession.EnableFilter(“SoftDeleteFilter”).Validate();