我正在使用Web.api和Unity，当我尝试打开默认的“帮助”区域时，我收到以下错误：
[InvalidOperationException: The type String cannot be constructed. You must configure the container to supply this value.] Microsoft.Practices.ObjectBuilder2.DynamicmethodConstructorStrategy.GuardTypeIsNonPrimitive(IBuilderContext context,SelectedConstructor selectedConstructor) +280 Microsoft.Practices.ObjectBuilder2.DynamicmethodConstructorStrategy.PreBuildUp(IBuilderContext context) +356 Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) +260 Microsoft.Practices.ObjectBuilder2.DynamicmethodBuildplanCreatorPolicy.CreatePlan(IBuilderContext context,NamedTypeBuildKey buildKey) +205 Microsoft.Practices.ObjectBuilder2.BuildplanStrategy.PreBuildUp(IBuilderContext context) +231 Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) +260 Microsoft.Practices.ObjectBuilder2.BuilderContext.NewBuildUp(NamedTypeBuildKey newBuildKey) +250 Microsoft.Practices.Unity.ObjectBuilder.NamedTypeDependencyResolverPolicy.Resolve(IBuilderContext context) +101 BuildUp_System.Web.Http.HttpRouteCollection(IBuilderContext ) +202 Microsoft.Practices.ObjectBuilder2.DynamicmethodBuildplan.BuildUp(IBuilderContext context) +42 Microsoft.Practices.ObjectBuilder2.BuildplanStrategy.PreBuildUp(IBuilderContext context) +319 Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) +260 Microsoft.Practices.ObjectBuilder2.BuilderContext.NewBuildUp(NamedTypeBuildKey newBuildKey) +250 Microsoft.Practices.Unity.ObjectBuilder.NamedTypeDependencyResolverPolicy.Resolve(IBuilderContext context) +101 BuildUp_System.Web.Http.HttpConfiguration(IBuilderContext ) +202 Microsoft.Practices.ObjectBuilder2.DynamicmethodBuildplan.BuildUp(IBuilderContext context) +42 Microsoft.Practices.ObjectBuilder2.BuildplanStrategy.PreBuildUp(IBuilderContext context) +319 Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) +260 Microsoft.Practices.ObjectBuilder2.BuilderContext.NewBuildUp(NamedTypeBuildKey newBuildKey) +250 Microsoft.Practices.Unity.ObjectBuilder.NamedTypeDependencyResolverPolicy.Resolve(IBuilderContext context) +101 BuildUp_API.Areas.HelpPage.Controllers.HelpController(IBuilderContext ) +204 Microsoft.Practices.ObjectBuilder2.DynamicmethodBuildplan.BuildUp(IBuilderContext context) +42 Microsoft.Practices.ObjectBuilder2.BuildplanStrategy.PreBuildUp(IBuilderContext context) +319 Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) +260 Microsoft.Practices.Unity.UnityContainer.dobuildUp(Type t,Object existing,String name,IEnumerable`1 resolverOverrides) +373 [ResolutionFailedException: Resolution of the dependency Failed,type = "API.Areas.HelpPage.Controllers.HelpController",name = "(none)". Exception occurred while: while resolving. Exception is: InvalidOperationException - The type String cannot be constructed. You must configure the container to supply this value. ----------------------------------------------- At the time of the exception,the container was: Resolving API.Areas.HelpPage.Controllers.HelpController,(none) Resolving parameter "config" of constructor API.Areas.HelpPage.Controllers.HelpController(System.Web.Http.HttpConfiguration config) Resolving System.Web.Http.HttpConfiguration,(none) Resolving parameter "routes" of constructor System.Web.Http.HttpConfiguration(System.Web.Http.HttpRouteCollection routes) Resolving System.Web.Http.HttpRouteCollection,(none) Resolving parameter "virtualPathRoot" of constructor System.Web.Http.HttpRouteCollection(System.String virtualPathRoot) Resolving System.String,(none) ] Microsoft.Practices.Unity.UnityContainer.dobuildUp(Type t,IEnumerable`1 resolverOverrides) +436 Microsoft.Practices.Unity.UnityContainer.dobuildUp(Type t,IEnumerable`1 resolverOverrides) +50 Microsoft.Practices.Unity.UnityContainer.Resolve(Type t,ResolverOverride[] resolverOverrides) +48 Microsoft.Practices.Unity.UnityContainerExtensions.Resolve(IUnityContainer container,Type t,ResolverOverride[] overrides) +61 Unity.Mvc4.UnityDependencyResolver.GetService(Type serviceType) +140 System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext,Type controllerType) +87 [InvalidOperationException: An error occurred when trying to create a controller of type 'API.Areas.HelpPage.Controllers.HelpController'. Make sure that the controller has a parameterless public constructor.] System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext,Type controllerType) +247 System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext,Type controllerType) +438 System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext,String controllerName) +226 System.Web.Mvc.MvcHandler.ProcessRequestinit(HttpContextBase httpContext,IController& controller,IControllerFactory& factory) +326 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext,AsyncCallback callback,Object state) +177 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext,Object state) +88 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context,AsyncCallback cb,Object exTradata) +50 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +301 System.Web.HttpApplication.ExecuteStep(IExecutionStep step,Boolean& completedSynchronously) +155
我是新来的团结，我确定我错过了一步。
在webapiconfig.cs中：
public static void Register(HttpConfiguration config) { config.Routes.MapHttpRoute( name: "DefaultApi",routeTemplate: "api/{controller}/{action}/{id}",defaults: new { id = RouteParameter.Optional } ); //Custom formatter config.Formatters.Clear(); config.Formatters.Add(new JSONpformater()); config.EnableSystemDiagnosticsTracing(); //Setup DI Bootstrapper.Initialise(); }
Bootstraper.cs(默认值)
public static class Bootstrapper
{
public static IUnityContainer Initialise()
{
var container = BuildUnityContainer();
DependencyResolver.SetResolver(new UnityDependencyResolver(container));
return container;
}
private static IUnityContainer BuildUnityContainer()
{
var container = new UnityContainer();
// register all your components with the container here
// it is NOT necessary to register your controllers
// e.g. container.RegisterType<ITestService,TestService>();
RegisterTypes(container);
return container;
}
public static void RegisterTypes(IUnityContainer container)
{
}
}
<configSections> <!-- For more information on Entity Framework configuration,visit http://go.microsoft.com/fwlink/?LinkID=237468 --> <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection,EntityFramework,Version=5.0.0.0,Culture=neutral,PublicKeyToken=b77a5c561934e089" requirePermission="false" /> <section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection,Microsoft.Practices.Unity.Configuration"/> </configSections> <connectionStrings> <add name="DefaultConnection" providerName="System.Data.sqlClient" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=aspnet-API-20130708152001;Integrated Security=sspI;AttachDBFilename=|DataDirectory|\aspnet-API-20130708152001.mdf" /> <add name="<REMOVED>DBEntities" connectionString="Metadata=res://*/Models.DAL.<REMOVED>.csdl|res://*/Models.DAL.<REMOVED>.ssdl|res://*/Models.DAL.<REMOVED>.msl;provider=System.Data.sqlClient;provider connection string="data source=<REMOVED>;initial catalog=<REMOVED>;persist security info=True;user id=<REMOVED>;password=<REMOVED>;MultipleActiveResultSets=True;App=EntityFramework"" providerName="System.Data.EntityClient" />
<!--unity setting-->
<unity>
<containers>
<types>
<register type="API.Areas.HelpPage.Controllers.HelpController,API">
<constructor>
<param valu=""></param>
</constructor>
</register>
</types>
</containers>
</unity>
我朝着正确的方向前进吗？
谢谢
更新：
helpcontroller.cs：
public class HelpController : Controller
{
public HelpController()
: this(GlobalConfiguration.Configuration)
{
}
public HelpController(HttpConfiguration config)
{
Configuration = config;
}
public HttpConfiguration Configuration { get; private set; }
public ActionResult Index()
{
return View(Configuration.Services.GetApiExplorer().ApiDescriptions);
}
public ActionResult Api(string apiId)
{
if (!String.IsNullOrEmpty(apiId))
{
HelpPageApiModel apiModel = Configuration.GetHelpPageApiModel(apiId);
if (apiModel != null)
{
return View(apiModel);
}
}
return View("Error");
}
}
url我正在尝试访问：http：// hostname：port / Help
解决方法
作为你的代码示例，我假设你是一个控制器，而不是一个API控制器(从web api)。
您的api控制器依赖于HttpConfiguration的构造函数。容器可能没有这种类型的定义，因此不知道如何解决它，并且错误消息上的字符串应该来自这种类型作为依赖。我建议您使用GlobalConfiguration静态类并访问Configuration属性以获取HttpConfiguration实例。您可以在属性中抽象出样本：
// include this namespace using System.Web.Http; public class HelpController : Controller { // remove the constructors... // property protected static HttpConfiguration Configuration { get { return GlobalConfiguration.Configuration; } } public ActionResult Index() { return View(this.Configuration.Services.GetApiExplorer().ApiDescriptions); } public ActionResult Api(string apiId) { if (!String.IsNullOrEmpty(apiId)) { HelpPageApiModel apiModel = this.Configuration.GetHelpPageApiModel(apiId); if (apiModel != null) { return View(apiModel); } } return View("Error"); } }
现在，如果您使用的是Api控制器，则只需直接访问ApiController(Api控制器的基类)上的this.Configuration属性，并获取一个HttpConfiguration实例。
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