asp.net – “值不能为null或为空.当ModelState出错时,返回时最

我收到此错误：

Value cannot be null or empty. Parameter name: contentPath

在我看来这一行：

@Html.ValidationMessageFor(model => model.IssueName,"",new { @class = "text-danger" })

下面给出的堆栈跟踪似乎表明已经调用Url.Content,但我没有进行此类调用.下面是堆栈跟踪,然后是该行周围的一些代码行导致错误：

[ArgumentException: Value cannot be null or empty. Parameter name:
contentPath] System.Web.Mvc.UrlHelper.GenerateContentUrl(String
contentPath,HttpContextBase httpContext) +125
System.Web.Mvc.UrlHelper.Content(String contentPath) +26
ASP._Page_Views_Journal_EditIssue_cshtml.Execute() in
MyProjectViewsJournalEditIssue.cshtml:45
System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +197
System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +105
System.Web.WebPages.StartPage.RunPage() +17
System.Web.WebPages.StartPage.ExecutePageHierarchy() +64
System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext
pageContext,TextWriter writer,WebPageRenderingBase startPage) +78
System.Web.Mvc.RazorView.RenderView(ViewContext viewContext,
TextWriter writer,Object instance) +256
System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext
viewContext,TextWriter writer) +107
System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
+291 System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext
controllerContext,ActionResult actionResult) +13
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList1
filters,Int32 filterIndex,ResultExecutingContext preContext,
ControllerContext controllerContext,ActionResult actionResult) +56
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList1
filters,ActionResult actionResult) +420
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext
controllerContext,IList1 filters,ActionResult actionResult) +52
System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c()
+173 System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult
asyncResult) +100
System.Web.Mvc.Async.WrappedAsyncResult1.CallEndDelegate(IAsyncResult
asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult
asyncResult) +27
System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult
asyncResult,ExecuteCoreState innerState) +13
System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult
asyncResult) +29
System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +36
System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult
asyncResult,Controller controller) +12
System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult
asyncResult) +22
System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49
System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult
asyncResult) +10
System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult
asyncResult,ProcessRequestState innerState) +21
System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult
asyncResult) +29
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult)
+28 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult
result) +9
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
+9644097 System.Web.HttpApplication.ExecuteStep(IExecutionStep step,Boolean& completedSynchronously) +155

抛出异常的行周围的代码行是：

<div class="form-group">
    @Html.LabelFor(model => model.IssueName,htmlAttributes: new { @class = "control-label col-md-2"})
    <div class="col-md-10">
        @Html.EditorFor(model => model.IssueName,new { htmlAttributes = new { @class = "form-control",id = "IssueName" } })
        @Html.ValidationMessageFor(model => model.IssueName,new { @class = "text-danger" })
    </div>
</div>

重要

奇怪的是,只有当我从post-back返回时才会引发异常,从来没有在我第一次加载视图时,甚至在ModelState没有错误时也是如此.只有当ModelState在回发后出现错误时才会引发它.

这是一些服务器端代码,但我没有看到任何可能出错的原因：

[HttpPost]
public async Task<ActionResult> EditIssue(EditIssueViewModel viewModel)
{
    viewModel.AvailableTags = BusinessManager.GetAllTags();

    if (viewModel.IssuePDFFile == null || viewModel.IssuePDFFile.ContentLength == 0)
    {
        ModelState.AddModelError("","Please select a file to upload.");
        return View(viewModel);
    }

    var fileInfo = new FileInfo(viewModel.IssuePDFFile.FileName);
    if (!StaticData.AcceptedContentTypes.Contains(viewModel.IssuePDFFile.ContentType,StringComparer.InvariantCultureIgnoreCase) ||
        !fileInfo.Extension.Equals(".pdf",StringComparison.InvariantCultureIgnoreCase))
    {
        ModelState.AddModelError("","You can only select a PDF file.");
        return View(viewModel);
    }

    if (!ModelState.IsValid)
    {
        var errors = ModelState.Values.SelectMany(v => v.Errors)
            .Select(e => new { e.ErrorMessage,e.Exception });

        var errorList = errors.ToList();

        errorList.ForEach(e => Debug.Print(e.ErrorMessage));
        errorList.ForEach(e => ModelState.AddModelError("",e.ErrorMessage));

        return View(viewModel);
    }

    var operationResult = await BusinessManager.EditIssueAsync(viewModel);

    if (!operationResult.Succeeded)
    {
        ModelState.AddModelError("",operationResult.FailureMessage);
        return View(viewModel);
    }

    viewModel = (EditIssueViewModel)BusinessManager.GetIssueWithRelationships(viewModel.IssueId);
    viewModel.SuccessMessage = operationResult.SuccessMessage;
    return View(viewModel);
}