Question

为什么我在员工控制器上收到此错误，其余的工作正常这是我的员工控制器

public class EmployeeController : ApiController
    {
        #region Call service
        private readonly IEmployeeServices _employeeServices;
        public EmployeeController(IEmployeeServices employeeServices)
        {
            _employeeServices = employeeServices;
        }

        readonly IEmployeeServices employeeServices = new EmployeeServices();

        public EmployeeController():base()
        {
            _employeeServices = employeeServices;
        }
}

这是我完美的工作产品控制器

public class ProductController : ApiController
    {
        #region Call service

        private readonly IProductServices _productServices;

        public ProductController(IProductServices productServices)
        {
            _productServices = productServices;
        }

        readonly IProductServices productServices = new ProductServices();

        public ProductController()
        {
            _productServices = productServices;
        }
}

这是堆栈跟踪

发生错误。尝试创建＆＃39; EmployeeController＆＃39;类型的控制器时发生错误。确保控制器在System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create（HttpRequestMessage请求，HttpControllerDescriptor controllerDescriptor，Type controllerType）＆＃13;中具有无参数公共构造函数.System.InvalidOperationException。在System.Web.Http.Controllers.HttpControllerDescriptor.CreateController（HttpRequestMessage request）＆＃13;在System.Web.Http.Dispatcher.HttpControllerDispatcher。＆lt; SendAsync＆gt; d__1.MoveNext（）发生错误。依赖关系的解析失败，输入=＆＃34; TheWork.Controllers.EmployeeController＆＃34;，name =＆＃ 34;（无）＆＃34;＆＃13;在解决时发生异常。＆＃13;异常是：InvalidOperationException - 当前类型BusinessServices.IEmployeeServices是一个接口，无法构造。你错过了类型映射吗？＆＃13; -----------------------------------------------＆＃13 ;在例外时，容器是：＆＃13; ＆＃13;解决TheWork.Controllers.EmployeeController，（无）＆＃13;解决参数＆＃34; employeeServices＆＃34;构造函数TheWork.Controllers.EmployeeController（BusinessServices.IEmployeeServices employeeServices）＆＃13;解决BusinessServices.IEmployeeServices，（无）＆＃13; Microsoft.Practices.Unity.UnityContainer.DoBuildUp（Type t，Object existing，String name，IEnumerable 1 resolverOverrides) at Microsoft.Practices.Unity.UnityContainer.Resolve(Type t, String name, ResolverOverride[] resolverOverrides) at Microsoft.Practices.Unity.UnityContainerExtensions.Resolve(IUnityContainer container, Type t, ResolverOverride[] overrides) at Unity.WebApi.UnityDependencyScope.GetService(Type serviceType) at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func 1＆amp; activator）＆＃13; Microsoft.Practices.Unity.ResolutionFailedException。在System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create（HttpRequestMessage请求，HttpControllerDescriptor controllerDescriptor，类型controllerType）发生错误。当前类型BusinessServices.IEmployeeServices是一个接口，无法构造。您是否缺少类型映射？Microsoft.Practices.ObjectBuilder2.DynamicMethodConstructorStrategy.ThrowForAttemptingToConstructInterface（IBuilderContext context）＆＃13;中的System.InvalidOperationException在lambda_method（Closure，IBuilderContext）＆＃13;在Microsoft.Practices.ObjectBuilder2.DynamicBuildPlanGenerationContext。＆lt;＆gt; c__DisplayClass1。＆lt; GetBuildMethod＆gt; b__0（IBuilderContext context）＆＃13;在Microsoft.Practices.ObjectBuilder2.DynamicMethodBuildPlan.BuildUp（IBuilderContext context）＆＃13;在Microsoft.Practices.ObjectBuilder2.BuildPlanStrategy.PreBuildUp（IBuilderContext context）＆＃13;在Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp（IBuilderContext context）＆＃13;在Microsoft.Practices.ObjectBuilder2.BuilderContext.NewBuildUp（NamedTypeBuildKey newBuildKey）＆＃13;在Microsoft.Practices.Unity.ObjectBuilder.NamedTypeDependencyResolverPolicy.Resolve（IBuilderContext context）＆＃13;在lambda_method（Closure，IBuilderContext）＆＃13;在Microsoft.Practices.ObjectBuilder2.DynamicBuildPlanGenerationContext。＆lt;＆gt; c__DisplayClass1。＆lt; GetBuildMethod＆gt; b__0（IBuilderContext context）＆＃13;在Microsoft.Practices.ObjectBuilder2.DynamicMethodBuildPlan.BuildUp（IBuilderContext context）＆＃13;在Microsoft.Practices.ObjectBuilder2.BuildPlanStrategy.PreBuildUp（IBuilderContext context）＆＃13;在Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp（IBuilderContext context）＆＃13;在Microsoft.Practices.Unity.UnityContainer.DoBuildUp（Type t，Object existing，String name，IEnumerable`1 resolverOverrides）

更新

这是Unity配置

   public static class UnityConfig
    {
        public static void RegisterComponents()
        {
            var container = new UnityContainer();
            System.Web.Mvc.DependencyResolver.SetResolver(new UnityDependencyResolver(container));

            GlobalConfiguration.Configuration.DependencyResolver = new Unity.WebApi.UnityDependencyResolver(container);

            RegisterTypes(container);
        }

        public static void RegisterTypes(IUnityContainer container)
        {
            ComponentLoader.LoadContainer(container, ".\\bin", "TheWork.dll");
            ComponentLoader.LoadContainer(container, ".\\bin", "BusinessServices.dll");
            ComponentLoader.LoadContainer(container, ".\\bin", "DataModel.dll");
        }
}

Answer 1

埋藏在堆栈跟踪中是问题的根本原因：

InvalidOperationException - 当前类型 BusinessServices.IEmployeeServices，是一个界面，不能 的构造。你错过了类型映射吗？ - - - - - - - - - - - - - - - - - - - - - - - - 当时例外，容器是：解决 TheWork.Controllers.EmployeeController，（无）解析参数＆＃34; employeeServices＆＃34;构造函数 TheWork.Controllers.EmployeeController（BusinessServices.IEmployeeServices employeeServices）解析BusinessServices.IEmployeeServices，（无） Microsoft.Practices.Unity.ResolutionFailedException at Microsoft.Practices.Unity.UnityContainer.DoBuildUp（Type t，Object existing，String name，IEnumerable1 resolverOverrides）

问题是EmployeeController需要IEmployeeServices的实例，但Unity不知道要实例化的具体类型。看起来实现类应该通过调用ComponentLoader.LoadContainer(container, ".\\bin", "BusinessServices.dll");来注册，但由于某种原因它没有被注册。它可能是该代码中的错误，或者可能是BusinessServices.dll已过期且不包含IEmployeeServices定义。

如果没有看到所有代码和运行时依赖项（因为动态加载/注册类型），就很难说IEmployeeServices未注册的原因。

Answer 2

确保控制器具有无参数的公共构造函数

public class EmployeeController : ApiController
    {
        #region Call service
        private readonly IEmployeeServices _employeeServices;
        public EmployeeController(IEmployeeServices employeeServices)
        {
            _employeeServices = employeeServices;
        }

        readonly IEmployeeServices employeeServices = new EmployeeServices();

        public EmployeeController()
        {
            _employeeServices = employeeServices;
        }
}

Answer 3

尝试这种方式:)

        /// Load your modules or register your services here!
        /// </summary>
        /// <param name="kernel">The kernel.</param>
        private static void RegisterServices(IKernel kernel)
        {
            kernel.Bind<IEmployeeServices >().To<EmployeeServices >().InRequestScope();
        }

尝试创建类型为＆＃39; EmployeeController＆＃39;的控制器时发生错误。确保控制器具有无参数的公共构造函数

3 个答案: