Ninject在具有多个程序集的WebApi项目中抛出Activation Exception

Question

我的asp.net WebApi项目包含多个服务,核心和数据访问程序集.为了在项目中使用Ninject作为我的DI容器,我从NuGet添加了Ninject.Web.Common包.然后,我实现了IDependencyResolver:

public class NinjectDependencyResolver : NinjectDependencyScope, IDependencyResolver
{
    readonly IKernel kernel;

    public NinjectDependencyResolver(IKernel kernel) : base(kernel)
    {
        this.kernel = kernel;
    }

    public IDependencyScope BeginScope()
    {
        return new NinjectDependencyScope(this.kernel.BeginBlock());
    }
}

public class NinjectDependencyScope : IDependencyScope
{
    IResolutionRoot resolver;

    public NinjectDependencyScope(IResolutionRoot resolver)
    {
        this.resolver = resolver;
    }

    public object GetService(System.Type serviceType)
    {
        if (resolver == null)
            throw new ObjectDisposedException("this", "This scope has been disposed");

        var resolved = this.resolver.Get(serviceType);
        return resolved;
    }

    public System.Collections.Generic.IEnumerable<object> GetServices(System.Type serviceType)
    {
        if (resolver == null)
            throw new ObjectDisposedException("this", "This scope has been disposed");

        return this.resolver.GetAll(serviceType);
    }

    public void Dispose()
    {
        IDisposable disposable = resolver as IDisposable;
        if (disposable != null)
            disposable.Dispose();

        resolver = null;
    }
}

这是我的Ninject.Web.Common.cs.

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();
        kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
        kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();
        RegisterServices(kernel);

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

    /// <summary>
    /// Load your modules or register your services here!
    /// </summary>
    /// <param name="kernel">The kernel.</param>
    private static void RegisterServices(IKernel kernel)
    {
        kernel.Bind(x =>
            x.FromAssembliesInPath(AppDomain.CurrentDomain.RelativeSearchPath)
            .SelectAllIncludingAbstractClasses()
            .BindDefaultInterface()
            .Configure(config => config.InSingletonScope()));

        //kernel.Bind(x => 
        //    {
        //        x.FromAssembliesMatching("*")
        //        .SelectAllClasses()
        //        .BindDefaultInterface()
        //        .Configure(b => b.InTransientScope());
        //    });
        //kernel.Load()
        //kernel.Bind<ISecurityService>().To<SecurityServiceImplementation>();

        //kernel.Bind(x => x
        //    .FromAssembliesMatching("*")
        //    .SelectAllClasses()
        //    .BindDefaultInterface());
        //.Configure(b => b.InTransientScope()));
        //kernel.Load("*.dll");
    }        
}

例外是

[ActivationException: Error activating IHostBufferPolicySelector
No matching bindings are available, and the type is not self-bindable.
Activation path:
1) Request for IHostBufferPolicySelector

我已经使用了各种注册(已注释掉)但没有工作.命中NinjectWebCommon.cs - > CreateKernel()方法中的断点,GetService(System.Type serviceType)方法中的断点也是如此.AppDomain.CurrentDomain.RelativeSearchPath解析为应用程序的bin目录,它包含所有dll,包括System.Web.Http.dll,其中包含IHostBufferPolicySelector类型.

如何正确使用Ninject.Extensions.Conventions来设置内核以进行类型解析？

Answer 1

从Remo的回答提示和Filip的评论以及大量的调试时间,我发现使用this.resolver.Get(serviceType)而不是this.resolver.TryGet(serviceType)在GetService()实现是我的情况的罪魁祸首.

我计划了一篇关于此的详细博客文章,但缺点是,一旦我们使用该行将NinjectDependencyResolver插入MVC: GlobalConfiguration.Configuration.DependencyResolver = new NinjectDependencyResolver(kernel); 并且我们没有定义框架级依赖项绑定(例如IHostBufferPolicySelector等),则会引发异常.一些框架级依赖关系的Get()方法,当它们没有通过Ninject解析时.使用不会引发异常,并且框架会回退到未解析的(a.ka. null)依赖项(如IHostBufferPolicySelector)的默认依赖项.所以,选项是TryGet()

1. 使用TryGet()方法解决依赖关系.
2. Wrap Get in Try/Catch并丢弃该异常.