public ActionResult Delete(int?id)
        {
            if (!id.HasValue)
            {
                return(new HttpStatusCodeResult(HttpStatusCode.BadRequest));
            }
            Material material = m_repo.GetMaterial(id.Value);

            if (material == null)
            {
                return(HttpNotFound());
            }
            m_repo.DeleteMaterial(material);
            return(RedirectToAction("Index"));
        }