SignalR结构图依赖项解析器（为Microsoft.AspNet.SignalR.Messaging.IMessageBus指定）

Question

我该如何解决这个错误？

版本

Microsoft.AspNet.SignalR.Core 2.2.0，structuremap 3.1.4.143

global.asax signalR依赖解析

// SIGNALR DEPENDENCY RESOLVER
        GlobalHost.DependencyResolver = new StructureMapSignalRDependencyResolver(Container ?? ObjectFactory.Container);

StructureMapSignalRDependencyResolver

public class StructureMapSignalRDependencyResolver : DefaultDependencyResolver
{
    private readonly IContainer _container;
    public StructureMapSignalRDependencyResolver(IContainer container)
    {
        _container = container;
    }

    public override object GetService(Type serviceType)
    {
        object service = null;
        //Below is a key difference between this StructureMap example, GetInstance is used for concrete classes.
        if (!serviceType.IsAbstract && !serviceType.IsInterface && serviceType.IsClass)
        {
            //If the type is a concrete type we get here...
            service = _container.GetInstance(serviceType);
        }
        else
        {
            // Non concrete resolution which uses the base dependency resolver if needed.
            service = _container.TryGetInstance(serviceType) ?? base.GetService(serviceType);
        }
        return service;
    }

    public override IEnumerable<object> GetServices(Type serviceType)
    {
        var objects = _container.GetAllInstances(serviceType).Cast<object>();
        return objects.Concat(base.GetServices(serviceType));
    }
}

erorr

没有注册默认实例，无法自动确定类型为“Microsoft.AspNet.SignalR.Messaging.IMessageBus”

没有为Microsoft.AspNet.SignalR.Messaging.IMessageBus指定配置

1.）新的AckSubscriber（IMessageBus的默认值，IAckHandler的默认值）2。）Microsoft.AspNet.SignalR.Infrastructure.AckSubscriber 3.）Microsoft.AspNet.SignalR.Infrastructure.AckSubscriber的实例4.）Container.GetInstance（Microsoft.AspNet .SignalR.Infrastructure.AckSubscriber）

Answer 1

首先尝试从基类解析。

    public override object GetService(Type serviceType)
    {
        if (serviceType == null)
            return null;

        var service = base.GetService(serviceType);
        if (service != null) return service;

        return (!serviceType.IsAbstract && !serviceType.IsInterface && serviceType.IsClass)
            ? container.GetInstance(serviceType)
            : container.TryGetInstance(serviceType);
    }

Answer 2

上面的@ajm回答绕过了我的错误，但是我发现我的客户端方法都没有被调用。

事实证明，SignalR.Infrastructure.PrincipalUserIdProvider正在被解决，而不是我的自定义IUserIdProvider所以我必须首先添加容器检查稍微修改他的答案。

    public override object GetService(Type serviceType)
    {
        if (serviceType == null)
            return null;

        var service = _container.TryGetInstance(serviceType) ?? base.GetService(serviceType);
        if (service != null) return service;

        return (!serviceType.IsAbstract && !serviceType.IsInterface && serviceType.IsClass)
            ? _container.GetInstance(serviceType)
            : _container.TryGetInstance(serviceType);
    }

如果您不使用StructureMap 3，则仍需要辅助容器检查，因为TryGetInstance()会为具体类型返回null。

Answer 3

我发现暂时，但错误仍在继续..我怎么能注册这个{Name =“AckSubscriber”FullName =“Microsoft.AspNet.SignalR.Infrastructure.AckSubscriber”}

临时解决方案是try catch，在catch返回null

    public override object GetService(Type serviceType)
    {

        try
        {
            object service = null;
            //Below is a key difference between this StructureMap example, GetInstance is used for concrete classes.
            if (!serviceType.IsAbstract && !serviceType.IsInterface && serviceType.IsClass)
            {
                //If the type is a concrete type we get here...
                service = _container.GetInstance(serviceType);
            }
            else
            {
                // Non concrete resolution which uses the base dependency resolver if needed.
                service = _container.TryGetInstance(serviceType) ?? base.GetService(serviceType);
            }
            return service;
        }
        catch (Exception exc)
        {
            return null;
        }
    }

Answer 4

我使用基于Ninject的解析器时遇到了类似的问题。在这种情况下，解决方案是确保Ninject具有IDependencyResolver的绑定，类似于此。

var resolver = new NinjectResolver(kernel);
kernel.Bind<IDependencyResolver>().ToConstant(resolver);
GlobalHost.DependencyResolver = resolver;

AckSubscriber有2个构造函数。

public AckSubscriber(IDependencyResolver resolver)
public AckSubscriber(IMessageBus messageBus, IAckHandler ackHandler)

看起来由于某种原因，它不是试图通过依赖解析器创建这个类，而是试图通过底层的IOC容器创建这个类。因为所有这些类的绑定都在DefaultDependencyResolver中，所以容器不知道它们是什么，所以错误。通过为IDependencyResolver指定绑定，它能够使用第一个构造函数并按预期工作。