使用 Ninject 和 Web API 2.1 注入 API 控制器时出现 InvalidOperationException

Question

我目前无法让 Ninject 将依赖项注入我的 API 控制器。我正在使用带有 MVC 5、Web API 2.1 和 SignalR 2 的 Web 项目。我使用的是 5.1.2 版的 Web API、3.2.2 版的 Ninject 和 3.2.1 版的 Ninject.Web.WebApi.Webhost。每次我向 API 发出请求时，都会收到此错误：

    System.InvalidOperationException: An error occurred when trying to create a controller of type 'AccountsController'. Make sure that the controller has a parameterless public constructor. ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at Ninject.Planning.Bindings.BindingConfiguration.GetProvider(IContext context)
   at Ninject.Planning.Bindings.Binding.GetProvider(IContext context)
   at Ninject.Activation.Context.GetProvider()
   at Ninject.Activation.Context.ResolveInternal(Object scope)
   at Ninject.Activation.Context.Resolve()
   at Ninject.KernelBase.<>c__DisplayClass15.<Resolve>b__f(IBinding binding)
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
   at Ninject.Planning.Targets.Target`1.GetValue(Type service, IContext parent)
   at Ninject.Planning.Targets.Target`1.ResolveWithin(IContext parent)
   at Ninject.Activation.Providers.StandardProvider.GetValue(IContext context, ITarget target)
   at Ninject.Activation.Providers.StandardProvider.<>c__DisplayClass4.<Create>b__2(ITarget target)
   at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
   at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at Ninject.Activation.Providers.StandardProvider.Create(IContext context)
   at Ninject.Activation.Context.ResolveInternal(Object scope)
   at Ninject.Activation.Context.Resolve()
   at Ninject.KernelBase.<>c__DisplayClass15.<Resolve>b__f(IBinding binding)
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
   at Ninject.Planning.Targets.Target`1.GetValue(Type service, IContext parent)
   at Ninject.Planning.Targets.Target`1.ResolveWithin(IContext parent)
   at Ninject.Activation.Providers.StandardProvider.GetValue(IContext context, ITarget target)
   at Ninject.Activation.Providers.StandardProvider.<>c__DisplayClass4.<Create>b__2(ITarget target)
   at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
   at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at Ninject.Activation.Providers.StandardProvider.Create(IContext context)
   at Ninject.Activation.Context.ResolveInternal(Object scope)
   at Ninject.Activation.Context.Resolve()
   at Ninject.KernelBase.<>c__DisplayClass15.<Resolve>b__f(IBinding binding)
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
   at Ninject.Web.WebApi.NinjectDependencyScope.GetService(Type serviceType)
   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator)
   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)
   --- End of inner exception stack trace ---
   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)
   at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request)
   at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsyncCore(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at System.Web.Http.HttpServer.<SendAsync>d__0.MoveNext()

这是它试图实例化的控制器：

public class AccountsController : ApiControllerBase
{
    private IAuthenticationService _auth;
    private IConfigurationManager _config;
    private static readonly ILog LOG = LogManager.GetLogger(typeof(AccountsController));

    public AccountsController(IAuthorizationService authService, IAuthenticationService auth, IConfigurationManager config)
        : base(authService)
    {
        _auth = auth;
        _config = config;
    }

这是我的Startup.cs 文件：

公共类启动 { 公共静态 IKernel 内核 { 获取；私人套装； }

    static Startup()
    {
        Kernel = new StandardKernel();
        RegisterServices(Kernel);
    }
    public void Configuration(IAppBuilder app)
    {
        // For more information on how to configure your application, visit http://go.microsoft.com/fwlink/?LinkID=316888



        var webApiConfig = ConfigureWebApi(Kernel);

        app.UseWebApi(webApiConfig);
    }

    public static HttpConfiguration ConfigureWebApi(IKernel kernel)
    {
        var config = new HttpConfiguration();
        config.DependencyResolver = new Ninject.Web.WebApi.NinjectDependencyResolver(kernel);

        //Formatting
        config.Formatters.Remove(config.Formatters.XmlFormatter);
        config.Formatters.Remove(config.Formatters.JsonFormatter);
        config.Formatters.Add(new JsonMediaTypeFormatter()
        {
            SerializerSettings = JsonSettings.SETTINGS,
            Indent = true,
        });

        //Error handling
        config.Services.Add(typeof(IExceptionLogger), new Log4NetExceptionLogger());
        config.Services.Replace(typeof(IExceptionHandler), new EntityErrorExceptionHandler());

        //Routing
        config.MapHttpAttributeRoutes();
        config.EnsureInitialized();
        return config;
    }


    private static void RegisterServices(IKernel kernel)
    {
        kernel.Load<ConfigurationModule>();
        kernel.Load<ResourceModule>();
        kernel.Load<SecurityModule>();

        kernel.Bind<IEmailService>().To<Email.SendGridService>();


    }
}

这些模块包含所有必要的依赖项。我已经验证他们都被正确绑定了。有谁知道为什么我仍然会收到此错误？有什么可以解决的吗？

Answer 1

我找到了解决方案。这只是我的一个愚蠢的错误。我的依赖绑定配置不正确。要是给了我一个更有帮助的例外就好了……