Automatic Timestamping for Entity Framework

I was looking for a way to get ADO.NET Entity Framework to do magic timestamping à la Ruby on Rails ActiveRecord. I couldn't find any built in mechanism to accomplish this. Here's what I came up with:

public partial class MyEntityContext
{
 partial void OnContextCreated()
 {
  SavingChanges += OnSavingChanges;
 }

 private void OnSavingChanges(object sender, EventArgs e)
 {
  var now = DateTime.Now;
  foreach (var entry in ObjectStateManager.GetObjectStateEntries(EntityState.Added | EntityState.Modified))
  {
   if (!entry.IsRelationship)
   {
    var timestampedEntity = entry.Entity as ITimestampedEntity;
    if (timestampedEntity != null)
    {
     timestampedEntity.DateModified = now;
     var entity = entry.Entity as EntityObject;
     if (entity != null && entity.EntityState == EntityState.Added)
     {
      timestampedEntity.DateCreated = now;
     }
    }
   }
  }
 }
}

internal interface ITimestampedEntity
{
 DateTime DateCreated { get; set; }
 DateTime DateModified { get; set; }
}

Now for every entity that implements the ITimestampedEntity interface, the DateCreated and DateModified fields will automagically be set/updated.

The above code is covered under the Logos Code Blog License.