Question

我是Dependency Injection的新手，也是使用推荐的ninjectKernel作为DI框架的书，这里引用了book。我在以下方法中遇到错误：

 protected override IController GetControllerInstance(RequestContext requestContext, Type controllerType)
        {
            return controllerType == null
                ? null
                : (IController)ninjectKernel.Get(controllerType);
        }

它抛出

无法将“System.String”类型的对象强制转换为“SportsStore.Domain.Concrete.EmailSettings”。

这个工作完全正常，直到它确实添加了绑定（下面）。

private void AddBindings() {

    ninjectKernel.Bind<IProductsRepository>().To<EFProductRepository>();

    EmailSettings emailSettngs = new EmailSettings {
        WriteAsFile = bool.Parse(ConfigurationManager
            .AppSettings["Email.WriteAsFile"] ?? "false")
    };

    ninjectKernel.Bind<IOrderProcessor>()
        .To<EmailOrderProcessor>()
        .WithConstructorArgument("settings", "emailSettings");
}

你能在这里给我一些提示吗？

这是堆栈跟踪：

[InvalidCastException：无法将“System.String”类型的对象强制转换为“SportsStore.Domain.Concrete.EmailSettings”。] DynamicInjectorc4f1546a04fc4966a278bd8198a4edff（Object []）+123 Ninject.Activation.Providers.StandardProvider.Create（IContext context）+884 Ninject.Activation.Context.ResolveInternal（对象范围）+218 Ninject.Activation.Context.Resolve（）+277 Ninject。＆lt;＆gt; c__DisplayClass15.b__f（IBinding binding）+86 System.Linq.WhereSelectEnumerableIterator 2.MoveNext() +145 System.Linq.Enumerable.SingleOrDefault(IEnumerable 1 source）+4059897 Ninject.Planning.Targets.Target 1.GetValue(Type service, IContext parent) +169 Ninject.Planning.Targets.Target 1.ResolveWithin（IContext parent）+747 Ninject.Activation.Providers.StandardProvider.GetValue（IContext context，ITarget target）+269 Ninject.Activation.Providers。＆lt;＆gt; c__DisplayClass4.b__2（ITarget target）+69 System.Linq.WhereSelectArrayIterator 2.MoveNext() +66 System.Linq.Buffer 1..ctor（IEnumerable 1 source) +323 System.Linq.Enumerable.ToArray(IEnumerable 1 source）+77 Ninject.Activation.Providers.StandardProvider.Create（IContext context）+847 Ninject.Activation.Context.ResolveInternal（对象范围）+218 Ninject.Activation.Context.Resolve（）+277 Ninject。＆lt;＆gt; c__DisplayClass15.b__f（IBinding binding）+86 System.Linq.WhereSelectEnumerableIterator 2.MoveNext() +145 System.Linq.Enumerable.Single(IEnumerable 1 source）+191 Ninject.ResolutionExtensions.Get（IResolutionRoot root，Type service，IParameter []参数）+70 在C：\ dev \ aspnet \ Workout \ SportsStore \ SportsStore.WebUI \ Infrastructure \ NinjectControllerFactory.cs中的SportsStore.WebUI.Infrastructure.NinjectControllerFactory.GetControllerInstance（RequestContext requestContext，Type controllerType）：26 System.Web.Mvc.DefaultControllerFactory.CreateController（RequestContext requestContext，String controllerName）+74 System.Web.Mvc.MvcHandler.ProcessRequestInit（HttpContextBase httpContext，IController＆amp; controller，IControllerFactory＆amp; factory）+193 System.Web.Mvc.MvcHandler.BeginProcessRequest（HttpContextBase httpContext，AsyncCallback回调，对象状态）+49 System.Web.Mvc.MvcHandler.BeginProcessRequest（HttpContext httpContext，AsyncCallback回调，对象状态）+49 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest（HttpContext context，AsyncCallback cb，Object extraData）+16 System.Web.Mvc。＆lt;＆gt; c__DisplayClass7.b__6（）+31 System.Web.Mvc.ServerExecuteHttpHandlerWrapper.Wrap（Func 1 func) +27 System.Web.Mvc.ServerExecuteHttpHandlerAsyncWrapper.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +98 System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride) +2019 System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage) +76 System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm) +28 System.Web.HttpServerUtilityWrapper.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm) +19 System.Web.Mvc.Html.ChildActionExtensions.ActionHelper(HtmlHelper htmlHelper, String actionName, String controllerName, RouteValueDictionary routeValues, TextWriter textWriter) +477 System.Web.Mvc.Html.ChildActionExtensions.RenderAction(HtmlHelper htmlHelper, String actionName, String controllerName) +34 ASP._Page_Views_Shared__Layout_cshtml.Execute() in c:\dev\aspnet\Workout\SportsStore\SportsStore.WebUI\Views\Shared\_Layout.cshtml:12 System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +197 System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +96 System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +88 System.Web.WebPages.<>c__DisplayClass7.<RenderPageCore>b__6(TextWriter writer) +233 System.Web.WebPages.HelperResult.WriteTo(TextWriter writer) +10 System.Web.WebPages.WebPageBase.Write(HelperResult result) +71 System.Web.WebPages.WebPageBase.RenderSurrounding(String partialViewName, Action 1 body）+64 System.Web.WebPages.WebPageBase.PopContext（）+246 System.Web.WebPages.WebPageBase.ExecutePageHierarchy（WebPageContext pageContext，TextWriter writer，WebPageRenderingBase startPage）+95 System.Web.Mvc.RazorView.RenderView（ViewContext viewContext，TextWriter writer，Object instance）+259 System.Web.Mvc.BuildManagerCompiledView.Render（ViewContext viewContext，TextWriter writer）+115 System.Web.Mvc.ViewResultBase.ExecuteResult（ControllerContext context）+294 System.Web.Mvc.ControllerActionInvoker.InvokeActionResult（ControllerContext controllerContext，ActionResult actionResult）+13 System.Web.Mvc。＆lt;＆gt; c__DisplayClass1a.b__17（）+23 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter（IResultFilter过滤器，ResultExecutingContext preContext，Func 1 continuation) +242 System.Web.Mvc.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() +21 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList 1过滤器，ActionResult actionResult）+175 System.Web.Mvc.Async。＆lt;＆gt; c__DisplayClass2a.b__20（）+89 System.Web.Mvc.Async。＆lt;＆gt; c__DisplayClass25.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。＆lt;＆gt; c__DisplayClass4.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（）+9690172 System.Web.HttpApplication.ExecuteStep（IExecutionStep step，Boolean＆amp; completedSynchronously）+155

Answer 1

您将字符串传递给构造函数参数而不是emailSettings对象。取消字符串emailSettings。

ninjectKernel.Bind<IOrderProcessor>()
    .To<EmailOrderProcessor>()
    .WithConstructorArgument("settings", emailSettings);

在ninject框架中绑定时出现Typecast错误

1 个答案: