C# 异常过帐，视图模型具有dictionary属性，由enum设置关键字，类为值

编辑：我不确定以前是怎么漏掉的，但这可能是重复的

我使用的是ASP.NET MVC4，我有一个字典属性，该属性在枚举上设置了键，并且有一个类作为其值类型。我正在使用

Html.TextBoxFor

为表单生成Html，并将其中一个作为视图模型的控制器操作。当我通过浏览器提交表单时，我在绑定过程中收到一个

InvalidCastException

以下是视图模型：

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

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

这是堆栈跟踪。（我有一个不同类型的模型活页夹，但对于这个dictionary属性，它只是传递到

base.BindModel

）

[InvalidCastException:指定的强制转换无效。]
System.Web.Mvc.CollectionHelpers.ReplaceDictionaryImpl（IDictionary`2 dictionary，IEnumerable`1 newContents）+131
[TargetInvocationException:调用的目标已引发异常。]
System.RuntimeMethodHandle.InvokeMethod（对象目标、对象[]参数、签名符号、布尔构造函数）+0
System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal（对象obj，对象[]参数，对象[]参数）+92
System.Reflection.RuntimeMethodInfo.Invoke（对象obj、BindingFlags invokeAttr、Binder Binder、对象[]参数、CultureInfo区域性）+108
System.Reflection.MethodBase.Invoke（对象obj，对象[]参数）+19
System.Web.Mvc.CollectionHelpers.ReplaceDictionary（类型keyType、类型valueType、对象字典、对象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.BindCompleteXelementalModel（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__显示类25.b__1e（AsyncCallback AsyncCallback，Object asyncState）+446
System.Web.Mvc.Async.WrappedAsyncResult`1.Begin（异步回调，对象状态，Int32超时）+130
System.Web.Mvc.Async.AsyncControllerActionInvoker.BeginInvokeAction（ControllerContext ControllerContext，String actionName，AsyncCallback回调，对象状态）+302
System.Web.Mvc.c_uuudisplayClassId.b_uuu17（异步回调，异步回调，对象异步状态）+30
System.Web.Mvc.Async.WrappedAsyncResult`1.Begin（异步回调，对象状态，Int32超时）+130
System.Web.Mvc.Controller.BeginExecuteCore（异步回调，对象状态）+382
System.Web.Mvc.Async.WrappedAsyncResult`1.Begin（异步回调，对象状态，Int32超时）+130
System.Web.Mvc.Controller.BeginExecute（RequestContext RequestContext，AsyncCallback回调，对象状态）+317
System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.BeginExecute（RequestContext RequestContext，AsyncCallback回调，对象状态）+15
System.Web.Mvc.c_uuudisplayClass8.b_uuu2（异步回调，异步回调，对象异步状态）+71
System.Web.Mvc.Async.WrappedAsyncResult`1.Begin（异步回调，对象状态，Int32超时）+130
System.Web.Mvc.MvcHandler.BeginProcessRequest（HttpContextBase httpContext，异步回调，对象状态）+249
System.Web.Mvc.MvcHandler.BeginProcessRequest（HttpContext HttpContext，异步回调，对象状态）+50
System.Web.Mvc.MvcHandler.System.Web.IHTTPassynchandler.BeginProcessRequest（HttpContext上下文，AsyncCallback cb，Object extraData）+16
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute（）+301
System.Web.HttpApplication.ExecuteStep（IExecutionStep步骤，布尔值&同步完成）+155

您似乎忘记了在

POST

操作中重新填充

MyViewModel

的

Subs

属性。您必须在

GET

和

POST

请求中执行此操作

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"
                            }
                        }
                    }
                }
}

在行动后再次：

public ActionResult EditPage(MyViewModel model)
{
    model.Subs = GetSubsDict();
    return View(model);
}

---

执行永远不会到达后操作。发布的数据不绑定。如果我在POST操作的第一行中放置断点，它将永远不会到达。谢谢你的回答。

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

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

[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

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"
                            }
                        }
                    }
                }
}

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

public ActionResult EditPage(MyViewModel model)
{
    model.Subs = GetSubsDict();
    return View(model);
}