public IActionResult Add(ActivityModel model)
        {
            if (ModelState.IsValid)
            {
                var activity = _repository.GetActivity(model.Key);
                return RedirectToAction("Index");
            }

            return View(model);
        }
 public IActionResult Delete(ActivityModel model)
 {
     _repository.Remove(_repository.GetActivity(model.Key));
     return RedirectToAction("Index");
 }