EntityFramework错误处理

public void Insert(PageHost entity)
{
try
{
db.pagehost.Add(entity);
db.SaveChanges();
}
catch (DbEntityValidationException ep)
{
CatchException(ep);
}
catch (Exception ep)
{
throw ep;
}
}

private void CatchException(DbEntityValidationException ep)
{
StringBuilder sb = new StringBuilder();
foreach (DbEntityValidationResult item in ep.EntityValidationErrors)
{
foreach (string pp in item.Entry.OriginalValues.PropertyNames)
{
sb.AppendLine(item.Entry.Member(pp).CurrentValue.ToString());
}
foreach (DbValidationError i in item.ValidationErrors)
{
throw new Exception(string.Format("{0}\t{1}\t{2}", i.PropertyName, i.ErrorMessage, sb.ToString()));
}
}
}