Inheritance: ISessionSelectLists
 public void UpdateSession(Guid speakerId, int sessionId, EditSessionModel model)
 {
     var session = GetSession(speakerId, sessionId);
     var theEvent = GetEvent(model.EventId);
     session.Event = theEvent;
     model.MapTo(session);
     repository.SaveChanges();
 }
 public ActionResult EditSession(Guid speakerId, int id, EditSessionModel model)
 {
     if (ModelState.IsValid) {
         service.UpdateSession(speakerId, id, model);
         return RedirectToAction("Details", new {speakerId, id});
     }
     SetSelectLists(model);
     return View(model);
 }