实体框架6 - GetObjectStateEntries预期修改实体具有状态"未更改"

问题

当我创建我的帐户类作为示例A时,对象在我的SaveChanges() - 方法中按预期显示状态为"EntityState.Modified".

当我使用示例B时,该对象显示为"EntityState.Unchanged",并且在GetObjectStateEntries(EntityState.Added | EntityState.Modified)调用的结果中没有apear.

任何人都可以向我解释,为什么模型对象在示例B中看起来没有变化,而一切都在示例A中有效？

谢谢

类

我在Context对象中使用此方法更新'Created'和'LastUpdated':

public class CrmContext : DbContext
{

public override int SaveChanges()
{
    DateTime now = DateTime.Now;
    foreach (ObjectStateEntry entry in (this as IObjectContextAdapter).ObjectContext.ObjectStateManager.GetObjectStateEntries(EntityState.Added | EntityState.Modified))
    {
        if (!entry.IsRelationship)
        {
            var account = entry.Entity as Account;
            if (account != null)
            {
                account.LastUpdated = now;
                if (entry.State == EntityState.Added)
                {
                    account.Created = now;
                }
            }
        }
    }

    return base.SaveChanges();
}

}

模型示例A(工作):

public class Account
{
 [Key]
 public int AccountId { get; set; }
 public string Name { get; set; }
 [Timestamp]
 public Byte[] TimeStamp { get; set; }
 public DateTime Created { get; set; }
 public DateTime LastUpdated { get; set; }
}

模型示例B(不工作):

public class Account : BaseObject
{
 [Key]
 public int AccountId { get; set; }
 public string Name { get; set; }
}
public class BaseObject
{
 [Timestamp]
 public Byte[] TimeStamp { get; set; }
 public DateTime Created { get; set; }
 public DateTime LastUpdated { get; set; }
}

更新:

该问题似乎与模型类是否继承自基类有关,因为我不能在不使用建议的DetectChanges()调用的情况下重现工作示例.