使用SimpleInjector中的IAuthorizationFilter进行依赖项注入

问题描述

我有一个 PermissionFilter 类，该类实现了 System.Web.Mvc 中的 IAuthorizationFilter .由于它具有已经映射的依赖项，因此我想使用SimpleInjector来提供它.

I have a class PermissionFilter that implements IAuthorizationFilter from System.Web.Mvc. Since it has dependencies that are already mapped, I want to use SimpleInjector to provide it.

我正在这样做(与Ninject一起使用):

I'm doing this (which was working with Ninject):

public static void RegisterGlobalFilters(GlobalFilterCollection filters)
{
    filters.Add(DependencyResolver.Current.GetService(typeof(PermissionFilter)));
}

但是我得到了错误:

我试图从容器中获取 PermissionFilter 的实例:

I tried to get an instance of the PermissionFilter from the container:

var permissionFilter = container.GetInstance(typeof(PermissionFilter));
filters.Add(permissionFilter);

但是使用SimpleInjector时，它会到达以下代码:

But with SimpleInjector, when it reaches this code:

container.RegisterMvcControllers(Assembly.GetExecutingAssembly());

我收到一条 InvalidOperationException 并显示以下消息:

I get an InvalidOperationException with the message:

推荐答案

在编写问题时，SO提示我检查此问题和，由.他在那说:

As I was writing the question, I was prompted by SO to check this question and the great answer by Steven. There he says:

相反，您应该创建一个代理类，该代理类可以在使用过滤器时委派回您的容器/内核，以便可以当场解析实际的过滤器.这样可以防止强制依赖性.

Instead, you should create a proxy class that can delegate back to your container/kernel at the time the filter is used, so it can resolve the real filter on the spot. This prevents Captive Dependencies.

所以，我最终编写了这个代理类:

So, I ended up writing this proxy class:

public class AuthorizationFilterProxy<TFilter> : IAuthorizationFilter
    where TFilter : class, IAuthorizationFilter
{
    private readonly Container Container;

    public AuthorizationFilterProxy(Container container)
    {
        Container = container;
    }

    public void OnAuthorization(AuthorizationContext context)
    {
        Container.GetInstance<TFilter>().OnAuthorization(context);
    }
}

添加过滤器:

public static void RegisterGlobalFilters(
    GlobalFilterCollection filters, Container container)
{
    // Since PermissionFilter is a root type (i.e. directly resolved from the container),
    // it should be explicitly registered. This allows it to be verified.
    container.Register<PermissionFilter>();

    filters.Add(new AuthorizationFilterProxy<PermissionFilter>(container));
}

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