后操作中的 ViewModel 属性 Null

Question

现在已修复。下面 Ish 的建议加上在视图中添加对 @HiddenFor 的调用解决了这个问题。

我有一个 ASP.NET MVC 5 Web 应用程序，用户可以在其中将缺陷标记为已解决。我想显示一个潜在相关缺陷的列表，用户可以勾选复选框以表明是的，这是同一个缺陷，也应该标记为已解决。

所以我有一个视图模型，它的属性是一个集合，它的每个成员都包含一个缺陷对象属性和布尔值IsSameDefect 属性。这在 GET 操作方法和视图中都可以正常工作。我可以显示相关的缺陷并打勾。

当我想更新数据时，问题出现在 POST 操作中。此时属性（潜在相关缺陷的集合）为空。我很难弄清楚如何将这些数据传回控制器？

请求的代码...

// GET: /DefectResolution/Create
public ActionResult Create(int ciid)
{
    int companyId = User.CompanyID();
    DefectResolutionCreateViewModel drcvm = new DefectResolutionCreateViewModel(ciid, companyId);
    return View(drcvm);
}

// POST: /DefectResolution/Create
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(DefectResolutionCreateViewModel drcvm)
{
    DefectResolutions currentResolution = drcvm.DefectResolution;
    currentResolution.CreatedOn = System.DateTime.Now;
    currentResolution.UserID = User.UserID();

    if (ModelState.IsValid)
    {
        unitOfWork.DefectResolutionRepository.Insert(currentResolution);

        if (currentResolution.ResolutionStatusID == 2)
        {
            //code breaks here as drcvm.RelatedUnresolvedDefects is null
            foreach (var relatedDefect in drcvm.RelatedUnresolvedDefects)
            {
                if (relatedDefect.IsSameDefect)
                {
                    DefectResolutions relatedResolution = new DefectResolutions();
                    relatedResolution.ChecklistID = relatedDefect.RelatedChecklist.ChecklistID;
                    relatedResolution.CreatedOn = System.DateTime.Now;
                    relatedResolution.ResolutionNote = currentResolution.ResolutionNote;
                    relatedResolution.ResolutionStatusID = currentResolution.ResolutionStatusID;
                    relatedResolution.UserID = User.UserID();
                }
            }
        }

        unitOfWork.Save();
        return RedirectToAction("Index", new { ciid = currentResolution.ChecklistID });
    }
    return View(drcvm);
}

在视图中...

@model Blah.ViewModels.DefectResolution.DefectResolutionCreateViewModel
@{
    ViewBag.Title = "Create Defect Resolution";
    var relatedDefects = Model.RelatedUnresolvedDefects;
}

... 以及稍后在视图中...

 @for (int i = 0; i < relatedDefects.Count(); i++ )
{
    <tr>
        <td>
            @Html.EditorFor(x => relatedDefects[i].IsSameDefect)
        </td>
    </tr>
}                       

我遵循了 Ish 在下面的建议，并修改了代码以直接引用 Model.RelatedUnresolvedDefects，而不是像我一直在做的那样使用变量。这确实让我更进一步。视图模型的 RelatedUnresolvedDefects 属性不再为空。但只有 RelatedUnresolvedDefects.IsSameDefect 有值。 RelatedUnresolvedDefects.RelatedChecklist 为空。这是控制器代码，再次显示了它现在中断的位置...

// POST: /DefectResolution/Create
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(DefectResolutionCreateViewModel drcvm)
{
    DefectResolutions currentResolution = drcvm.DefectResolution;
    currentResolution.CreatedOn = System.DateTime.Now;
    currentResolution.UserID = User.UserID();

    if (ModelState.IsValid)
    {
        unitOfWork.DefectResolutionRepository.Insert(currentResolution);

        if (currentResolution.ResolutionStatusID == 2)
        {
            //prior to change, code used to break here
            foreach (var relatedDefect in drcvm.RelatedUnresolvedDefects)
            {
                if (relatedDefect.IsSameDefect)
                {
                    DefectResolutions relatedResolution = new DefectResolutions();

                    //code now breaks here because relatedDefect.RelatedChecklist is null
                    relatedResolution.ChecklistID = relatedDefect.RelatedChecklist.ChecklistID;
                    relatedResolution.CreatedOn = System.DateTime.Now;
                    relatedResolution.ResolutionNote = currentResolution.ResolutionNote;
                    relatedResolution.ResolutionStatusID = currentResolution.ResolutionStatusID;
                    relatedResolution.UserID = User.UserID();
                }
            }
        }

        unitOfWork.Save();
        return RedirectToAction("Index", new { ciid = currentResolution.ChecklistID });
    }
    return View(drcvm);
}

Answer 1

在不知道您的代码的情况下。我建议您在渲染 View (.cshtml) 中的缺陷时使用 for 循环而不是 foreach。

根据您的代码编辑答案。
视图中的以下语句创建问题

 var relatedDefects = Model.RelatedUnresolvedDefects;

您应该直接在循环中遍历Model.RelatedUnresolvedDefects 属性。

             @for (int i = 0; i < Model.RelatedUnresolvedDefects.Count(); i++ )
                        {
                            <tr>
                                <td>
                                    @Html.EditorFor(x => Model.RelatedUnresolvedDefects[i].IsSameDefect)
                                </td>
                            </tr>
                        }