MVC /剃刀：錯誤在Viewbag.Title

我有兩種方法：MVC /剃刀：錯誤在Viewbag.Title

public ActionResult Index() 
{ 
    var propList = db.Properties 
     .Where(x => x.SiteVisibilityFlags.HasFlag(Enums.SiteVisibilityFlags.Corporate) 
      || (x.SiteVisibilityFlagsOverride == true && x.SiteVisibilityFlagsOverrideValue.HasFlag(Enums.SiteVisibilityFlags.Corporate))) // just ones visible to 'Corporate' 
     .ToList(); 
    // Use view model 
    var pDVMs = DomainModelsToViewModels(propList); 
    return View(pDVMs); 
} 

public ActionResult Region(string id) // (regionId/marketId) 
{ 
    // make sure to replace the hyphens in the name 
    int marketId = db.Markets.Where(x => x.Name == id.Replace("-"," ")).FirstOrDefault().MarketID; 
    var tempList = db.Properties 
     .Where(x => x.SiteVisibilityFlags.HasFlag(Enums.SiteVisibilityFlags.Corporate) 
      || (x.SiteVisibilityFlagsOverride == true && x.SiteVisibilityFlagsOverrideValue.HasFlag(Enums.SiteVisibilityFlags.Corporate))) // just ones visible to 'Corporate' 
     .ToList(); 
    var propList = tempList.Where(x => x.MarketId == marketId).ToList(); 
    // Use view model 
    var pDVMs = DomainModelsToViewModels(propList); 
    return View("Index", pDVMs); 
}

都使用這一說法：

@model IEnumerable<woolbrightcorporatecms.viewmodels.propertydetailsviewmodel> 

    @{ 
    ViewBag.Title = "Portfolio"; 
    } 

    <h2 class="mapOverlay">Portfolio of Properties</h2> 

    <!-- Main map here with multiple 'markers'--> 
    <div class="container-full"> 
     <div id="map_canvas" style="height: 320px;" class="row"></div> 
    </div> 

    <div class="text-center" style="font-size: 32px; line-height: 38px; color: #FC543E;">Filter Region</div> 
    <div class="text-center" style="color:#5D6067; font-size: 14px; line-height: 17px;">Please choose from the following</div> 

    <br /><br /> 

    <ul class="list-inline text-center propertyRegionUL"> 
     <li data-marketid="Miami-Dade" class="regionLI @(ViewContext.RouteData.Values[" id"].tostring()= ="Miami-Dade" ? "active" 
      "")">Miami Dade</li> 
     <li data-marketid="Fort-Lauderdale" class="regionLI @(ViewContext.RouteData.Values[" id"].tostring()= ="Fort-Lauderdale" ? "active" 
      "")">Fort Lauderdale</li> 
     <li data-marketid="West-Palm-Beach" class="regionLI @(ViewContext.RouteData.Values[" id"].tostring()= ="West-Palm-Beach" ? "active" 
      "")">West Palm Beach</li> 
     <li data-marketid="Tampa" class="regionLI @(ViewContext.RouteData.Values[" id"].tostring()= ="Tampa" ? "active" 
      "")">Tampa</li> 
     <li data-marketid="Orlando" class="regionLI @(ViewContext.RouteData.Values[" id"].tostring()= ="Orlando" ? "active" 
      "")">Orlando</li> 
    </ul> 
    <br /><br /> 

    @* show prop name/city name 4 rows across *@ 
    <div class="propertyListWrapper text-center table col-md-8 col-md-offset-2"> 
     @{int columnCount = 0;} 
     @foreach (var item in Model) 
     { 
     if (columnCount == 0) 
     { 
     @:<div class="row"> 
      } 
      <div style="display:inline-block;" class="col-sm-2"> 
       <div class="propertyListName"> 
        <a href='@(Url.Action("Details", "Property", new { id = item.PropertyId }))'>@(item.Name)</a> 
       </div> 
       <div class="propertyListCity"> 
        <a href='@(Url.Action("Details", "Property", new { id = item.PropertyId }))'>@(item.City)</a> 
       </div> 
      </div> 
      if (columnCount == 3) 
      { 
      @: 
     </div> 
     } 
     columnCount++; 
     if (columnCount == 4) 
     { 
     columnCount = 0; 
     } 
     } 
    </div> 

    <script type="text/javascript"> 
     $(document).ready(function() { 
      // initialize map to center on florida. 
      initializeGMap(); 
      // serialize model locations 
      var locationsToPass = @Html.Raw(Json.Encode(Model.Select(x => new { x.Name, x.Location.Latitude, x.Location.Longitude }))); 
      // drop markers 
      addMarker(locationsToPass); 
      // filter by region/market 
      $('li.regionLI').click(function (ev) { 
       ev.preventDefault(); // just in case we decide to use anchor tags 
       // get id from element clicked AND make sure to reset previous values with 'new { id=""}' else it will append/ 
       var url = '@(Url.Action("Region", "Property", new { id = "" }))/' + $(this).data('marketid'); 
       window.location.href = url; 
      }); 
     }); 
    </script>

的 '索引' 的方法是原始/股法的視圖。它曾經工作得很好。沿線某處它開始拋出這個錯誤：

Object reference not set to an instance of an object. 

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object. 

Source Error: 


Line 4: 
Line 5: @{ 
Line 6:  ViewBag.Title = "Portfolio"; <-- HERE is where it errors 
Line 7: } 
Line 8:

這裏的堆棧跟蹤：

[NullReferenceException: Object reference not set to an instance of an object.] 
    ASP._Page_Views_Property_Index_cshtml.Execute() in c:\Users\bdamore.WDI\Source\WoolbrightCorporateCMS\WoolbrightCorporateCMS\Views\Property\Index.cshtml:4 
    System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +271 
    System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +121 
    System.Web.WebPages.StartPage.RunPage() +63 
    System.Web.WebPages.StartPage.ExecutePageHierarchy() +100 
    System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +131 
    System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +695 
    System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +382 
    System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +431 
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +39 
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +116 
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +529 
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +106 
    System.Web.Mvc.Async.<>c__DisplayClass2b.<begininvokeaction> 
    b__1c() +321 
    System.Web.Mvc.Async.<>c__DisplayClass21.<begininvokeaction> 
     b__1e(IAsyncResult asyncResult) +185 
     System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +42 
     System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +133 
     System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +56 
     System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +40 
     System.Web.Mvc.Controller.<beginexecutecore> 
      b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +34 
      System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +70 
      System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +139 
      System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59 
      System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40 
      System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +44 
      System.Web.Mvc.Controller.<beginexecute> 
       b__15(IAsyncResult asyncResult, Controller controller) +39 
       System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +62 
       System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +139 
       System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59 
       System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40 
       System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +39 
       System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +39 
       System.Web.Mvc.MvcHandler.<beginprocessrequest> 
        b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +39 
        System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +70 
        System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +139 
        System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59 
        System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40 
        System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +40 
        System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38 
        System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9651796 
        System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

兩種方法都返回有效對象。它只在'索引'上錯誤，而不在'區域'上錯誤。索引用於正常工作。我試圖刪除CSharp DLL並重新添加它無效，根據this article。我還審查了這些文章，但要麼不屬於我的問題還是沒有答案，我需要：

This article

Another one

來源

2015-06-17 Beau D' Amore

這是正確的，它正在視圖中設置。請參閱上面的 –

嘗試創建一個*最小的*代碼集，繼續導致錯誤。爲此，我建議一個新的動作+視圖，甚至沒有視圖模型。然後，您可以忽略所有令人困惑和最可能不相關的模型加載 –

'ViewBag'永遠不會爲空，因此'ViewBag.Title =「Portfolio」'絕不會引發該異常。顯示你的實際代碼。你真的使用'ViewBag.Title = Model.FirstOrDefault（）。SomeProperty'？ – CodeCaster

好了，罪魁禍首是這樣的：

<ul class="list-inline text-center propertyRegionUL"> 
    <li data-marketid="Miami-Dade" class="regionLI @(ViewContext.RouteData.Values["id"].ToString() == "Miami-Dade" ? "active" : "")">Miami Dade</li> 
    <li data-marketid="Fort-Lauderdale" class="regionLI @(ViewContext.RouteData.Values["id"].ToString() == "Fort-Lauderdale" ? "active" : "")">Fort Lauderdale</li> 
    <li data-marketid="West-Palm-Beach" class="regionLI @(ViewContext.RouteData.Values["id"].ToString() == "West-Palm-Beach" ? "active" : "")">West Palm Beach</li> 
    <li data-marketid="Tampa" class="regionLI @(ViewContext.RouteData.Values["id"].ToString() == "Tampa" ? "active" : "")">Tampa</li> 
    <li data-marketid="Orlando" class="regionLI @(ViewContext.RouteData.Values["id"].ToString() == "Orlando" ? "active" : "")">Orlando</li> 
</ul>

特別是「ViewContext.RouteData.Values [」id「]。ToString（）」行......如果我沒有傳入一個id，它就是在這裏轟炸。

感謝大家的想法和方向！

來源

2015-06-17 14:32:27

我強烈建議你考慮使用[viewmodels]（http://stackoverflow.com/questions/11064316/what-is-viewmodel-in-mvc）來存儲路由值數據，而不是直接調用'ViewContext.RouteData.Values .....在視圖本身。 –

好主意，謝謝！ –

這是爲了顯示哪個鏈接是「有效的」 –

ViewBag.Title上的NullReferenceException可以指示錯誤確實在附近的一行上。在我的情況下ViewBag錯誤是在第6行（@ ViewBag.Title）。但實際的錯誤是在第2行（ViewData [「PageHeader」]）一旦我從控制器設置PageHeader的視圖數據，空引用異常不再是

來源

2018-01-10 18:34:29 Ananth

MVC /剃刀：錯誤在Viewbag.Title

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