1

编辑： 我不确定我以前是怎么错过的，但这可能是Binding a dictionary contains a list in MVC4 的副本。

我正在使用 ASP.NET MVC4，并且我有一个字典属性，该属性以枚举为键，并有一个类作为其值类型。我正在使用Html.TextBoxFor为将其中之一作为视图模型的控制器操作生成表单的 HTML。InvalidCastException当我通过浏览器提交表单时，我在绑定期间得到了一个。

这是视图模型：

public class MyViewModel
{
    public virtual IDictionary<MyEnumType, IList<MySubViewModel>> Subs { get; set; }

    public class MySubViewModel
    {
        public virtual String Name { get; set; }
   }
}

在控制器中，我有：

[HttpGet]
public ActionResult EditPage(Int32? id)
{
    MyViewModel testViewModel = new MyViewModel
        {
            Subs = new Dictionary<MyEnumType, IList<MyViewModel.MySubViewModel>>() {
                {
                    MyEnumType.MySubViewModel
                  , new List<MyViewModel.MySubViewModel> {
                        new MyViewModel.MySubViewModel {
                            Name = "Foo-Bar"
                        }
                    }
                }
            }
        };
    return View(testViewModel);
}

[HttpPost]
public ActionResult EditPage(MyViewModel model)
{
    return View(model);
}

我认为（使用 Spark 视图引擎）：

<tbody each="var enumValue in Html.EnumValues<MyEnumType>()">
    <tr each="var sub in Model.Subs[enumValue]" class="DataRow">
        <td>
            ${Html.TextBoxFor(m => m.Subs[enumValue][subIndex].Name, new { @class="SubName" })}
        </td>
    </tr>
</tbody>

这被渲染为：

<tbody>
    <tr>
        <td>
            <input id="Subs_EnumValueOne__0__Name" type="text" value="Foo-Bar" name="Subs[EnumValueOne][0].Name">
        </td>
    </tr>
</tbody>

当我提交页面时，我得到一个InvalidCastException: {"Specified cast is not valid."}。

at System.Web.Mvc.DefaultModelBinder.CollectionHelpers.ReplaceDictionaryImpl[TKey,TValue](IDictionary`2 dictionary, IEnumerable`1 newContents)

这是堆栈跟踪。（我有一个不同类型的模型绑定器，但是对于这个字典属性，它只是传递给base.BindModel.）

[InvalidCastException: Specified cast is not valid.]
   System.Web.Mvc.CollectionHelpers.ReplaceDictionaryImpl(IDictionary`2 dictionary, IEnumerable`1 newContents) +131

[TargetInvocationException: Exception has been thrown by the target of an invocation.]
   System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor) +0
   System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments) +92
   System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) +108
   System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters) +19
   System.Web.Mvc.CollectionHelpers.ReplaceDictionary(Type keyType, Type valueType, Object dictionary, Object newContents) +178
   System.Web.Mvc.DefaultModelBinder.UpdateDictionary(ControllerContext controllerContext, ModelBindingContext bindingContext, Type keyType, Type valueType) +1211
   System.Web.Mvc.DefaultModelBinder.BindComplexModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +921
   System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +416
   Namespace.For.MyBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +1195
   System.Web.Mvc.DefaultModelBinder.GetPropertyValue(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor, IModelBinder propertyBinder) +17
   System.Web.Mvc.DefaultModelBinder.BindProperty(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor) +384
   System.Web.Mvc.DefaultModelBinder.BindProperties(ControllerContext controllerContext, ModelBindingContext bindingContext) +88
   System.Web.Mvc.DefaultModelBinder.BindComplexElementalModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Object model) +53
   System.Web.Mvc.DefaultModelBinder.BindComplexModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +1314
   System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +416
   Namespace.For.MyBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +1195
   System.Web.Mvc.ControllerActionInvoker.GetParameterValue(ControllerContext controllerContext, ParameterDescriptor parameterDescriptor) +317
   System.Web.Mvc.ControllerActionInvoker.GetParameterValues(ControllerContext controllerContext, ActionDescriptor actionDescriptor) +117
   System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__1e(AsyncCallback asyncCallback, Object asyncState) +446
   System.Web.Mvc.Async.WrappedAsyncResult`1.Begin(AsyncCallback callback, Object state, Int32 timeout) +130
   System.Web.Mvc.Async.AsyncControllerActionInvoker.BeginInvokeAction(ControllerContext controllerContext, String actionName, AsyncCallback callback, Object state) +302
   System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__17(AsyncCallback asyncCallback, Object asyncState) +30
   System.Web.Mvc.Async.WrappedAsyncResult`1.Begin(AsyncCallback callback, Object state, Int32 timeout) +130
   System.Web.Mvc.Controller.BeginExecuteCore(AsyncCallback callback, Object state) +382
   System.Web.Mvc.Async.WrappedAsyncResult`1.Begin(AsyncCallback callback, Object state, Int32 timeout) +130
   System.Web.Mvc.Controller.BeginExecute(RequestContext requestContext, AsyncCallback callback, Object state) +317
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.BeginExecute(RequestContext requestContext, AsyncCallback callback, Object state) +15
   System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__2(AsyncCallback asyncCallback, Object asyncState) +71
   System.Web.Mvc.Async.WrappedAsyncResult`1.Begin(AsyncCallback callback, Object state, Int32 timeout) +130
   System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +249
   System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +50
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +16
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +301
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155
4

1 回答 1

0

看起来您忘记在操作中重新填充您的Subs属性。您必须在 和请求中都这样做。MyViewModelPOSTGETPOST

您可以将其重构为一个方法并在两个操作中调用它：

private Dictionary<MyEnumType, IList<MyViewModel.MySubViewModel>> GetSubsDict()
{
    return new Dictionary<MyEnumType, IList<MyViewModel.MySubViewModel>>() 
                {
                    {
                        MyEnumType.MySubViewModel, 
                        new List<MyViewModel.MySubViewModel>
                        {
                            new MyViewModel.MySubViewModel
                            {
                                Name = "Foo-Bar"
                            }
                        }
                    }
                }
}

GET 操作：

public ActionResult EditPage(Int32? id)
{
    MyViewModel testViewModel = new MyViewModel
                                    {
                                        Subs = GetSubsDict();
                                    }
    return View(testViewModel);
}

并再次在 POST 操作中：

public ActionResult EditPage(MyViewModel model)
{
    model.Subs = GetSubsDict();
    return View(model);
}
于 2013-10-29T15:30:33.903 回答