ASP.NET MVC：如何在发布前后的控制器之间传递参数

Question

我有以下控制器：

// GET: /MaterialPaymentRequestSbuItem/CreateChild
public ActionResult CreateChild(int? parentId)
{
    if (parentId==null)
        return new HttpStatusCodeResult(HttpStatusCode.BadRequest);

    var parenetRequest = (from request in db.MaterialPaymentRequests
        where request.Id==(int)parentId
        select request);

    ViewBag.MaterialPaymentRequestId = new SelectList(parenetRequest, "Id", "Description", (int)parentId);
    ViewBag.ParentID = parentId;
    if (parenetRequest!=null && parenetRequest.First()!=null)
        ViewBag.ParentTitle = parenetRequest.First().Description;

    return View();
}

// POST: /MaterialPaymentRequestSbuItem/Create
// To protect from overposting attacks, please enable the specific properties you want to bind to, for 
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult CreateChild([Bind(Include = "Id,Name,Unit,UnitPrice,MaterialPaymentRequestId,Quantity")] MaterialPaymentRequestSubItem materialpaymentrequestsubitem)
{
    if (ModelState.IsValid)
    {
        try
        {
            db.MaterialPaymentRequestSubItems.Add(materialpaymentrequestsubitem);
            db.SaveChanges();
        }
        catch (Exception e)
        {
            return new HttpStatusCodeResult(HttpStatusCode.InternalServerError);
        }
        updateTotalPriceOfParentPaymentRequest(db, db.MaterialPaymentRequests.Find(materialpaymentrequestsubitem.MaterialPaymentRequestId));
        return RedirectToAction("List", new { id = materialpaymentrequestsubitem.MaterialPaymentRequestId });
    }

    ViewBag.MaterialPaymentRequestId = new SelectList(db.PaymentRequests, "Id", "Description", materialpaymentrequestsubitem.MaterialPaymentRequestId);
    //need to becheked
    ViewBag.ParentID = materialpaymentrequestsubitem.MaterialPaymentRequestId;
    if (Request != null && Request["parentID"] != null)
    {
        try
        {
            int id = Int32.Parse(Request["parentID"]);
            ViewBag.ParentTitle = db.MaterialPaymentRequests.Find(id).Description;
        }
        catch(Exception e)
        {

        }
    }
    return View(materialpaymentrequestsubitem);
}

我的主要问题是允许用户从下拉列表中选择 model.MaterialPaymentRequestId 并且他/她可能没有选择任何值。 MaterialPaymentRequestId 用于第一个控制器（在发布之前）从 db 中查找父标题并使用 ViewBag 将其传递给查看，但是如果用户没有选择 MaterialPaymentRequestId 下拉项目，在回发后，我丢失了 MaterialPaymentRequestId。目前，我阅读了Request 变量并在 url 内部查找参数以查找 parentID。 我的 url 调用类似于 http://localhost:46813/Admin/MaterialPaymentRequestSbuItem/CreateChild?parentId=23。

但是这种做法似乎是一种不好的做法，因为我不能在两个控制器方法之间传递 v 变量，如下所示：

控制器方法(get) ---> 查看 ---> 控制器方法(post)

目前我感觉有点卡在 MVC 中！

Answer 1

我希望我的观点正确，您可以在您的视图中使用@Html.hiddenfor(model => model.ParentId)，它将存储来自查询字符串的ParentId 值，并且当用户提交表单时将发布到 POST 方法，因此您无需查看 url为拿到它，为实现它。使用具有 ParentId 属性的视图模型并执行以下操作

public class MaterialPaymentsViewModel {
    //other properties
    public int ParentId {get;set;}
}

public ActionResult CreateChild(int? parentId)
{
    var model = new MaterialPaymentsViewModel{ParentId = parentId};
    //other stuff

    return View(model);
}

//View

@using (Html.beginform()){
//
@html.hiddenfor(m => m.ParentId)
//submit
}


[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult CreateChild(MaterialPaymentsViewModel  model)
{
    if(model.ParentId != null)
{
 //
}
  //
}