There is something called a ChainedPersistenceHandlerBase you can inherit from and intercept everything that goes to and from the database.

You can use override as you see fit:

1. public class UpdateHandler : ChainedPersistenceHandlerBase
2. {
3.   private readonly IObjectRepresentationProvider orp;
4.   public UpdateHandler(IObjectRepresentationProvider orp, IEcoTypeSystem typeSystem)
5.     : base(typeSystem)
6.   {
7.     this.orp = orp;
8.   }
9.   public override void UpdateDatabaseWithList(ICollection<Locator> locators)
10.   {
11.     DateTime timestamp = DateTime.Now;
12.     foreach (Locator loc in locators)
13.     {
14.       IObject obj = orp.IObjectForLocator(loc);
15.       if (obj.AsObject is ITrackUpdate)
16.       {
17.         (obj.AsObject as ITrackUpdate).PreUpdate(timestamp);
18.       }
19.     }
20.     base.UpdateDatabaseWithList(locators);
21.   }
22. }

Maybe you have a common base class for all classes in your model, and maybe this class implements an Interface ITrackUpdate, then it would be a good thing to catch all updates and set the DateTime…

1. public class UpdateHandler : ChainedPersistenceHandlerBase
2. {
3.   private readonly IObjectRepresentationProvider orp;
4.   public UpdateHandler(IObjectRepresentationProvider orp, IEcoTypeSystem typeSystem)
5.     : base(typeSystem)
6.   {
7.     this.orp = orp;
8.   }
9.   public override void UpdateDatabaseWithList(ICollection<Locator> locators)
10.   {
11.     DateTime timestamp = DateTime.Now;
12.     foreach (Locator loc in locators)
13.     {
14.       IObject obj = orp.IObjectForLocator(loc);
15.       if (obj.AsObject is ITrackUpdate)
16.       {
17.         (obj.AsObject as ITrackUpdate).PreUpdate(timestamp);
18.       }
19.     }
20.     base.UpdateDatabaseWithList(locators);
21.   }
22. }

We need to install our ChainedPersistenceHandlerBase baseclass. We do this by mixing it in before the current PersistenceHandler. We do this in the ecospace – before we go active:

1. // Install the update handler which intercepts all updates and updated the "Modified" attribute
2. UpdateHandler uh = new UpdateHandler(FrontsidePolicy.ObjectRepresentationProvider, TypeSystem);
3. PersistenceServiceImpl ps = Persistence as PersistenceServiceImpl;
4. uh.NextPersistenceHandler = ps.PersistenceHandler;
5. ps.PersistenceHandler = uh;
6. FrontsidePolicy.PersistenceHandler = uh;