Question

我正在开发一个ASP.NET MVC应用程序。在我的应用程序中，我需要提供REST API。所以我将Web Api 2添加到我现有的MVC应用程序中。在我添加Web API 2之前，我使用ninject进行依赖注入。我是通过Nuget Package安装的。整个网站已经开发和运作。但是当我将Web Api 2添加到我的项目时，问题就出现了。 Ninject for MVC不能与Web Api一起使用。所以我安装了Ninject for Web Api 2.所以我的NinjectWebCommon类在安装后已经改变了。

这是我在App_Start文件夹中的NinjectWebCommon文件

[assembly: WebActivatorEx.PreApplicationStartMethod(typeof(AyarDirectory.Web.App_Start.NinjectWebCommon), "Start")]
[assembly: WebActivatorEx.ApplicationShutdownMethodAttribute(typeof(AyarDirectory.Web.App_Start.NinjectWebCommon), "Stop")]

namespace AyarDirectory.Web.App_Start
{
    using System;
    using System.Web;

    using Microsoft.Web.Infrastructure.DynamicModuleHelper;

    using Ninject;
    using Ninject.Web.Common;

    public static class NinjectWebCommon 
    {
        private static readonly Bootstrapper bootstrapper = new Bootstrapper();

        /// <summary>
        /// Starts the application
        /// </summary>
        public static void Start() 
        {
            DynamicModuleUtility.RegisterModule(typeof(OnePerRequestHttpModule));
            DynamicModuleUtility.RegisterModule(typeof(NinjectHttpModule));
            bootstrapper.Initialize(CreateKernel);
        }

        /// <summary>
        /// Stops the application.
        /// </summary>
        public static void Stop()
        {
            bootstrapper.ShutDown();
        }

        /// <summary>
        /// Creates the kernel that will manage your application.
        /// </summary>
        /// <returns>The created kernel.</returns>
        private static IKernel CreateKernel()
        {
            var kernel = new StandardKernel();
            try
            {
                kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
                kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();

                RegisterServices(kernel);
                return kernel;
            }
            catch
            {
                kernel.Dispose();
                throw;
            }
        }

        /// <summary>
        /// Load your modules or register your services here!
        /// </summary>
        /// <param name="kernel">The kernel.</param>
        private static void RegisterServices(IKernel kernel)
        {
            System.Web.Mvc.DependencyResolver.SetResolver(new AyarDirectory.Web.Infrastructure.NinjectDependencyResolver(kernel));
        }        
    }
}

在我为web api安装ninject后，我只更改了那个地方。然后我运行我的应用程序。网站工作正常。网站仍在运作。但Web Api无效。

这是我的解析器类

namespace AyarDirectory.Web.Infrastructure
{
    public class NinjectDependencyResolver : IDependencyResolver
    {
        private IKernel kernel;

        public NinjectDependencyResolver(IKernel kernelParam)
        {
            kernel = kernelParam;
            AddBindings();
        }

        public object GetService(Type serviceType)
        {
            return kernel.TryGet(serviceType);
        }

        public IEnumerable<object> GetServices(Type serviceType)
        {
            return kernel.GetAll(serviceType);
        }

        private void AddBindings()
        {
            kernel.Bind<ICategoryRepo>().To<CategoryRepo>();

        }
    }
}

我在这样的Api Controller中进行依赖注入

public class RegionsController : ApiController
    {
        private IRegionRepo regionRepo;

        private RegionsController(IRegionRepo regionParam)
        {
            this.regionRepo = regionParam;
        }
         . . . }

当我访问api控制器的一个动作时，它正在给我跟随错误。

{"Message":"An error has occurred.","ExceptionMessage":"An error occurred when trying to create a controller of type 'RegionsController'. Make sure that the controller has a parameterless public constructor.","ExceptionType":"System.InvalidOperationException","StackTrace":"   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)\r\n   at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsyncCore(HttpRequestMessage request, CancellationToken cancellationToken)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__0.MoveNext()","InnerException":{"Message":"An error has occurred.","ExceptionMessage":"Type 'AyarDirectory.Web.Controllers.Api.RegionsController' does not have a default constructor","ExceptionType":"System.ArgumentException","StackTrace":"   at System.Linq.Expressions.Expression.New(Type type)\r\n   at System.Web.Http.Internal.TypeActivator.Create[TBase](Type instanceType)\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator)\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)"}}

那么，为什么它不起作用？我的代码有什么缺失或错误？请问我该如何解决？我如何使用Ninject for Web Api 2？我正在使用MVC 5.

Answer 1

下面再做两个步骤：

来自Nugget包经理：

install-package Ninject.Web.WebApi

现在编辑NinjectWebCommon.cs文件并在CreateKernel（）方法结束时和返回内核属性之前添加以下行：

GlobalConfiguration.Configuration.DependencyResolver = new NinjectDependencyResolver（kernel）;

返回内核;

Ninject for Web Api 2在ASP.NET MVC中不起作用

1 个答案: