使用简单注入器注入MVC​​控制器构造函数时，未注册参数

Question

我有什么似乎是使用简单注入器向MVC控制器注入依赖关系的一个非常基本的问题。之前使用过StructureMap的我使用Simple Injector是新手。

MVC的版本是4.5，它是从NuGet安装的最新版本的Simple Injector。

观看的HomeController的/索引视图时，我得到的错误是：

类型的HomeController的构造函数包含未注册名称“语境”型IContext的参数。请确保IContext已在容器中注册，或更改HomeController的构造函数。

控制器是这样：

public class HomeController : Controller 
{ 
    public HomeController(IContext context) { } 

    public ActionResult Index() { } 
} 

的IContext只是一个简单的界面：

public interface IContext 
{ 
} 

和具体IContext实现也很简单，仅仅是一个普通的DbContext的包装。

public class DbContext : System.Data.Entity.DbContext, IContext 
{ 

} 

对于信息的IContext接口生活在一个不同的项目VS /装配到的DbContext执行。这些被MVC项目引用。

我在我的Global.asax.cs如下：

protected void Application_Start() 
{ 
    var container = new Container(); 

    container.Register<IContext, DbContext>(); 

    container.RegisterMvcControllers(System.Reflection.Assembly.GetExecutingAssembly()); 

    container.RegisterMvcAttributeFilterProvider(); 

    container.Verify(); 

    DependencyResolver.SetResolver(new SimpleInjectorDependencyResolver(container)); 

    // Regular MVC startup 
    AreaRegistration.RegisterAllAreas(); 

    WebApiConfig.Register(GlobalConfiguration.Configuration); 
    FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters); 
    RouteConfig.RegisterRoutes(RouteTable.Routes); 
    BundleConfig.RegisterBundles(BundleTable.Bundles); 
} 

这是堆栈跟踪：

[ActivationException: The constructor of the type HomeController contains the parameter of type IContext with name 'context' that is not registered. Please ensure IContext is registered in the container, or change the constructor of HomeController.] 
SimpleInjector.Advanced.DefaultConstructorInjectionBehavior.BuildParameterExpression(ParameterInfo parameter) +229 
    SimpleInjector.Registration.BuildParameterExpressionFor(ParameterInfo parameter) +43 
    SimpleInjector.Registration.BuildConstructorParameters(ConstructorInfo constructor) +170 
    SimpleInjector.Registration.BuildNewExpression(Type serviceType, Type implementationType) +62 
    SimpleInjector.Registration.BuildTransientExpression() +85 
    SimpleInjector.Registration.BuildExpression(InstanceProducer producer) +62 
    SimpleInjector.InstanceProducer.BuildExpressionInternal() +42 
    System.Lazy`1.CreateValue() +14443208 
    System.Lazy`1.LazyInitValue() +476 
    SimpleInjector.InstanceProducer.BuildExpression() +159 

[ActivationException: The registered delegate for type HomeController threw an exception. The  constructor of the type HomeController contains the parameter of type IContext with name 'context' that is not registered. Please ensure IContext is registered in the container, or change the constructor of HomeController.] 
    SimpleInjector.InstanceProducer.BuildExpression() +257 
    SimpleInjector.InstanceProducer.VerifyExpressionBuilding() +53 

[InvalidOperationException: The configuration is invalid. Creating the instance for type HomeController failed. The registered delegate for type HomeController threw an exception. The constructor of the type HomeController contains the parameter of type IContext with name 'context' that is not registered. Please ensure IContext is registered in the container, or change the constructor of HomeController.] 
    SimpleInjector.InstanceProducer.VerifyExpressionBuilding() +161 
    SimpleInjector.Container.VerifyIfAllExpressionsCanBeBuilt(InstanceProducer[] producersToVerify) +45 
    SimpleInjector.Container.VerifyIfAllExpressionsCanBeBuilt() +166 
    SimpleInjector.Container.Verify() +39 
    MyMvcApp.App_Start.SimpleInjectorInitializer.Initialize() +216 

[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) +229 
    System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) +193 
    System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters) +35  
WebActivator.BaseActivationMethodAttribute.InvokeMethod() +341 
    WebActivator.ActivationManager.RunActivationMethods() +534 
    WebActivator.ActivationManager.RunPostStartMethods() +38 
    WebActivator.StartMethodCallingModule.Init(HttpApplication context) +159 
    System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +530 
    System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +304 
    System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +404 
    System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +475 

[HttpException (0x80004005): Exception has been thrown by the target of an invocation.] 
    System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +12889028 
    System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +159 
    System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +12730121 

我不知道为什么它不工作的所有代码是根据简单注射器快速入门指南。

Answer 1

请确保HomeController引用的IContext实际上与您在Application_Start中注册的IContext类型相同。最有可能的是，这是一种不同的类型。在注册中的IContext和HomeController中的IContext中执行到“Visual Studio”的“转到定义”，允许您确认Visual Studio是否跳转到相同的文件。

另一件事是检查你的代码所示Container实例是否是MVC中登记的实际（只）容器。去搜索应用程序中的任何其他new Container注册。

新版本简单的喷油器的实际向您发出一个非常具体的错误时，你的配置实际上包含了不同类型的具有相同的名称，所以它应该是很容易发现这些问题简单的注射器。并且当这种情况发生由不正确的动态组装加载引起时，异常消息is even more specific。