實現HTTP-POST的Edit Action方法

實現HTTP-POST的Edit Action方法

1.   [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult Edit(int id, FormCollection formValues) {}
表示該方法負責處理HTTP POST動作。

2.  擷取表單提交的值

一個簡單的辦法是使用Controller基類的Request屬性來訪問form集合，並直接擷取提交的參數值：

       public ActionResult Edit(int id, FormCollection formValues)
        {
            // Retrieve existing dinner
            Dinner dinner = dinnerRepository.GetDinner(id);
            // Update dinner with form posted values
            dinner.Title = Request.Form["Title"];
            dinner.Description = Request.Form["Description"];
            dinner.EventDate = DateTime.Parse(Request.Form["EventDate"]);
            dinner.Address = Request.Form["Address"];
            dinner.Country = Request.Form["Country"];
            dinner.ContactPhone = Request.Form["ContactPhone"];
            // Persist changes back to database
            dinnerRepository.Save();
            // Perform HTTP redirect to details page for the saved Dinner
            return RedirectToAction("Details", new { id = dinner.DinnerID });
        }

3.   使用Controller 基類的內建方法UpdateModel()。該方法支援使用傳入的表單參數更新對象的屬性，它使用反射機制來解析對象的屬性名稱，接著基於用戶端傳入的參數值自動賦值給對象相關屬性。
    [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult Edit(int id, FormCollection formValues)
        {
            // Retrieve existing dinner
            Dinner dinner = dinnerRepository.GetDinner(id);
            UpdateModel(dinner);
            // Persist changes back to database
            dinnerRepository.Save();
            // Perform HTTP redirect to details page for the saved Dinner
            return RedirectToAction("Details", new { id = dinner.DinnerID });
        }

4.   異常處理機制說明：
  try {}
  catch
            {
                foreach (var issue in dinner.GetRuleViolations())
                {
                    ModelState.AddModelError(issue.PropertyName, issue.ErrorMessage);
                }
                return View(dinner);
            }

在catch代碼塊中，首先遍曆Dinner對象中所有規則衝突，並添加到ModelState對象中，接著重新顯示視圖。