控制器的構造函數不採取參數mvc

Question

爲什麼當我爲控制器的構造函數添加一個參數時，出現錯誤。

這是我的代碼：

public partial class RegistrationController : Controller 
    { 

     public RegistrationController(int i) 
     { 


      } 
public ActionResult Index() 
    {} 

} 
the error is `Server Error in '/' Application. 
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 14: 
Line 15:  <fieldset> 
Line 16:   @{string visibleCountry = (Model.CountryParam == ConfigurationParamValue.NotVisible) ? "display:none" : "display:inline"; 
Line 17:   string mandatoryCountry = (Model.CountryParam == ConfigurationParamValue.isMandatory) ? "display:inline" : "display:none"; 
Line 18:   <div id="county" style="@visibleCountry"> 


Source File: e:\VP5-Nuguet\src\Registration\Registration.Front.Web\Views\Registration\Index.cshtml Line: 16 

Stack Trace: 


[NullReferenceException: Object reference not set to an instance of an object.] 
    ASP._Page_Views_Registration_Index_cshtml.Execute() in e:\VP5-Nuguet\src\Registration\Registration.Front.Web\Views\Registration\Index.cshtml:16 
    System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +197 
    System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +97 
    System.Web.WebPages.StartPage.RunPage() +17 
    System.Web.WebPages.StartPage.ExecutePageHierarchy() +62 
    System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +76 
    System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +260 
    System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +115 
    System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +295 
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13 
    System.Web.Mvc.<>c__DisplayClass1a.<InvokeActionResultWithFilters>b__17() +23 
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) +242 
    System.Web.Mvc.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() +21 
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +177 
    System.Web.Mvc.Async.<>c__DisplayClass2a.<BeginInvokeAction>b__20() +89 
    System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +102 
    System.Web.Mvc.Async.WrappedAsyncResult`1.End() +57 
    System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +43 
    System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +14 
    System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +23 
    System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62 
    System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +57 
    System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +23 
    System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62 
    System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +47 
    System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10 
    System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +25 
    System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +23 
    System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62 
    System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +47 
    System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9 
    System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9630364 
    System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.17929 ` 

Answer 1

如果你堅持，你必須建立自己的ControllerFactory實現IControllerFactory接口，並設置它在構造函數中的參數應用程序啓動。

ControllerBuilder.Current.SetControllerFactory(new MyControllerFactory()); 

Answer 2

MVC將嘗試通過調用其默認構造函數實例化在每個請求的路由指定的控制器。

從外觀上看，您想要找到如下網址：/registration/{someNumber}。

如果是這樣的情況下，從構造移動int id的動作方法：

public partial class RegistrationController : Controller 
{ 
     public RegistrationController() 
     { } 

     public ActionResult Index(int i) 
     { 
      // do something 
     } 
}