MVC 5 asp.net，從控制器到視圖的viewbag無法正常工作

Question

這是控制器

public ActionResult Test() {

@ViewBag.TheMessageIs = "this is the message";
return RedirectToAction("Details", new { id = theId});

} 

在Action Named Details的視圖中 ，我將檢查它是否有ViewBag來顯示和顯示它：

@{
  if(ViewBag.TheMessageIs != null){
         @ViewBag.TheMessageIs
  }
}

但是這里的重定向工作正常，它沒有顯示我存儲在ViewBag中的消息.MessageIs

謝謝

Answer 1

基本上你正在做的是從你的Index方法調用方法Details ，因為你已經用id重載了你的Details動作，所以也傳遞消息：

public ActionResult Index()
{
    //ViewBag.TheMessageIs = "this is the message";
    return RedirectToAction("Details", new { id = 1, TheMessageIs = "this is the message" });
}

public ActionResult Details(int id, string TheMessageIs)
{
    ViewBag.TheMessageIs = TheMessageIs;
    return View();
}

然后在Details視圖中，您可以像這樣訪問該屬性：

@ViewBag.TheMessageIs

Answer 2

public ActionResult Test() {
 TempData["shortMessage"] = "MyMessage";
 return RedirectToAction("Details", new { id = theId});
}

public ActionResult Details {
 //now I can populate my ViewBag (if I want to) with the TempData["shortMessage"] content
  ViewBag.TheMessageIs = TempData["shortMessage"].ToString();
  return View();
}

您必須這樣做，因為當您重定向到另一個活動/視圖時，viewbag會丟失其值