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Seeing everything that is persisted

From MDrivenWiki

There is something called a ChainedPersistenceHandlerBase that 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;