public ActionResult Edit(Product product)
        {
            if (ModelState.IsValid)
            {
                HttpPostedFileBase photo = Request.Files["productImg"];
                string strImage = SaveProductPhoto(photo, product.product_id);
                if (!string.IsNullOrEmpty(strImage))
                    product.product_image = strImage;

                db.Products.Attach(product);
                db.Entry(product).State = EntityState.Modified;
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            ViewBag.product_type_id = new SelectList(db.Ref_Product_Type, "product_type_id", "product_type_description_vn", product.product_type_id);
            ViewBag.product_uom_id = new SelectList(db.Unit_Of_Measure, "UOM_id", "UOM_description", product.product_uom_id);
            return View(product);
        }
        public ActionResult Create(Product product)
        {
            if (ModelState.IsValid)
            {
                try
                {
                    HttpPostedFileBase photo = Request.Files["productImg"];
                    product.product_image = SaveProductPhoto(photo);
                    product.product_created_date = DateTime.Now;

                    db.Products.Add(product);
                    db.SaveChanges();
                }
                catch (Exception ex)
                {
                    throw ex;
                }

                return RedirectToAction("Index");
            }
            ViewBag.product_type_id = new SelectList(db.Ref_Product_Type, "product_type_id", "product_type_description_vn", product.product_type_id);
            ViewBag.product_uom_id = new SelectList(db.Unit_Of_Measure, "UOM_id", "UOM_description", product.product_uom_id);
            return View(product);
        }