Question

我在使用Ninject的InSingletonScope与Web Api RC绑定时遇到了一些困难。无论我如何创建绑定，看起来Web Api可能正在处理范围/生命周期而不是Ninject。

我尝试了一些关于连接Ninject的变体。最常见的是与答案相同： ASP.NET Web API binding with ninject

我也试过这个版本： http://www.peterprovost.org/blog/2012/06/19/adding-ninject-to-web-api/

在两者中，我实际上创建了一个开箱即用的Web Api项目，然后按照任一帖子中的描述添加Ninject包。最后，我正在为StackOverflow版本添加Resolver和Scope类，例如：

public class NinjectDependencyScope : IDependencyScope
{
    private IResolutionRoot resolver;

    internal NinjectDependencyScope(IResolutionRoot resolver)
    {
        Contract.Assert(resolver != null);

        this.resolver = resolver;
    }

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

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

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

和

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

    public NinjectDependencyResolver(IKernel kernel)
        : base(kernel)
    {
        this.kernel = kernel;
    }
    public IDependencyScope BeginScope()
    {
        return new NinjectDependencyScope(kernel.BeginBlock());
    }
}

然后，NinjectWebCommon看起来像这样：

using System.Web.Http;
using MvcApplication2.Controllers;

[assembly: WebActivator.PreApplicationStartMethod(typeof(MvcApplication2.App_Start.NinjectWebCommon), "Start")]
[assembly: WebActivator.ApplicationShutdownMethodAttribute(typeof(MvcApplication2.App_Start.NinjectWebCommon), "Stop")]

namespace MvcApplication2.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();
            kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
            kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();

            // Register Dependencies
            RegisterServices(kernel);

            // Set Web API Resolver
            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<ILogger>().To<Logger>().InSingletonScope();
        }
    }
}

ILogger和Logger对象没有做任何事情，但说明了这个问题。 Logger执行Debug.Writeline，以便我可以看到它何时被实例化。每次刷新页面都会显示每次调用都会刷新，而不是我希望的单身。这是一个使用Logger的控制器：

public class ValuesController : ApiController
{
    private readonly ILogger _logger;
    public ValuesController(ILogger logger)
    {
        _logger = logger;
        _logger.Log("Logger created at " + System.DateTime.Now.ToLongTimeString());
    }
    // GET api/values
    public IEnumerable<string> Get()
    {
        return new string[] { "value1", "value2" };
    }
    // GET api/values/5
    public string Get(int id)
    {
        return "value";
    }
    // POST api/values
    public void Post(string value)
    {
    }
    // PUT api/values/5
    public void Put(int id, string value)
    {
    }
    // DELETE api/values/5
    public void Delete(int id)
    {
    }
}

当我将跟踪信息放入内核的创建时，似乎表明内核只创建了一次。那么......我没看到什么？单身人士为什么不坚持？

Answer 1

使用

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

并且不要将内核置于NinjectDependencyScope

中

Answer 2

@Remo Gloor 当我在WebAPI的InMemoryHost中运行代码并运行Integration测试时，一切正常，我有单例。如果我在VS Cassini Web服务器内运行WebAPI解决方案，则首先运行成功当我点击刷新时，我收到异常： 加载Ninject组件ICache时出错没有在内核的组件容器中注册此类组件。

如果我使用 BeginBlock 返回旧代码，它可以在Cassini中运行，但IsSingleton在集成测试中不再有效。

Answer 3

您可以简单地实现自己的单例，而不是不处理内核（不会调用内部部署）：

public static class NinjectSingletonExtension
{
    public static CustomSingletonKernelModel<T> SingletonBind<T>(this IKernel i_KernelInstance)
    {
        return new CustomSingletonKernelModel<T>(i_KernelInstance);
    }
}

public class CustomSingletonKernelModel<T>
{
    private const string k_ConstantInjectionName = "Implementation";
    private readonly IKernel _kernel;
    private T _concreteInstance;


    public CustomSingletonKernelModel(IKernel i_KernelInstance)
    {
        this._kernel = i_KernelInstance;
    }

    public IBindingInNamedWithOrOnSyntax<T> To<TImplement>(TImplement i_Constant = null) where TImplement : class, T
    {
        _kernel.Bind<T>().To<TImplement>().Named(k_ConstantInjectionName);
        var toReturn =
            _kernel.Bind<T>().ToMethod(x =>
                                       {
                                           if (i_Constant != null)
                                           {
                                               return i_Constant;
                                           }

                                           if (_concreteInstance == null)
                                           {
                                               _concreteInstance = _kernel.Get<T>(k_ConstantInjectionName);
                                           }

                                           return _concreteInstance;
                                       }).When(x => true);

        return toReturn;
    }
}

然后简单地使用：

i_Kernel.SingletonBind<T>().To<TImplement>();

而不是

i_Kernel.Bind<T>().To<TImplement>().InSingletonScope();

注意：虽然它只对第一个请求有用，但这个实现不是线程安全的。

Ninject InSingletonScope与Web Api RC

3 个答案: