带有 StructureMap 的 Asp.Net MVC 5 自定义动作过滤器

Question

我在使用结构映射的 asp.net mvc 自定义 acitonfilte 中遇到问题 在我的“LogAttribute”类中，我有 setter 依赖注入，当执行我的 customfilterclass 的“OnActionExecuted”方法时，它是“LogAttribute”

我的 LogAttribute 类代码是

    public class LogAttribute : ActionFilterAttribute
{
    public ApplicationDbContext Context { get; set; }
    public string Description { get; set; }
    public LogAttribute(string description)
    {
        Description = description;
    }

    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        var userId = filterContext.HttpContext.User.Identity.GetUserId();
        var user = Context.Users.Find(userId); **i am getting error here the Context is coming null here** 
        Context.Logs.Add(new Log(user, filterContext.ActionDescriptor.ActionName,
                                filterContext.ActionDescriptor.ControllerDescriptor.ControllerName,
                                Description
                                )
                        );
        Context.SaveChanges();
    }
}

我创建了另一个类，从那里我将值传递给 setter 依赖属性

    public class StructureMapFilterProvider : FilterAttributeFilterProvider 
{
    private readonly Func<IContainer> _container;
    public StructureMapFilterProvider(Func<IContainer> container)
    {
        _container = container;
    }

    public override IEnumerable<Filter> GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
    {
        var filters = base.GetFilters(controllerContext, actionDescriptor);
        var container = _container();
        foreach (var filter in filters)
        {
            container.BuildUp(filter.Instance);
            yield return filter;
        }
    }
}

我的依赖解析器类代码是

public class StructureMapDependencyResolver : IDependencyResolver
{
    private readonly Func<IContainer> _containerFactory;
    public StructureMapDependencyResolver(Func<IContainer> containerFactory)
    {
        _containerFactory = containerFactory;
    }
    public object GetService(Type serviceType)
    {
        if (serviceType == null)
        {
            return null;
        }
        var container = _containerFactory();

        return serviceType.IsAbstract || serviceType.IsInterface
            ? container.TryGetInstance(serviceType)
            : container.GetInstance(serviceType);
    }

    public IEnumerable<object> GetServices(Type serviceType)
    {
        return _containerFactory().GetAllInstances(serviceType).Cast<object>();
    }
}

我的 global.ascx 代码是

public class MvcApplication : System.Web.HttpApplication
{

    public IContainer Container
    {
        get
        {
            return (IContainer)HttpContext.Current.Items["_Container"];
        }
        set
        {
            HttpContext.Current.Items["_Container"] = value;
        }
    }

    protected void Application_Start()
    {
        AreaRegistration.RegisterAllAreas();
        FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
        RouteConfig.RegisterRoutes(RouteTable.Routes);
        BundleConfig.RegisterBundles(BundleTable.Bundles);
        DependencyResolver.SetResolver(new StructureMapDependencyResolver(() => Container ?? ObjectFactory.Container));

        ObjectFactory.Configure(cfg =>
           {
               cfg.Scan(Scan =>
               {
                   Scan.TheCallingAssembly();
                   Scan.WithDefaultConventions();
                   Scan.With(new ControllerConfiguration());
               });
               cfg.For<IFilterProvider>().Use(new StructureMapFilterProvider(() => Container ?? ObjectFactory.Container));
               cfg.For<IUserStore<ApplicationUser>>()
                  .Use<UserStore<ApplicationUser>>();
               cfg.For<DbContext>()
                  .Use(() => new ApplicationDbContext());
               cfg.SetAllProperties(x =>
                x.Matching(p =>
                     p.DeclaringType.CanBeCastTo(typeof(ActionFilterAttribute)) &&
                     p.DeclaringType.Namespace.StartsWith("TestingSturctureMap") &&
                     p.PropertyType.IsPrimitive &&
                     p.PropertyType != typeof(string)));

           });
    }

    public void Application_BeginRequest()
    {
        Container = ObjectFactory.Container.GetNestedContainer();
    }

    public void Application_EndRequest()
    {
        Container.Dispose();
        Container = null;
    }
}

Answer 1

我安装了structuremap 和StructureMap.MVC5 NuGet 包。
这将DependencyResolution 文件夹和StructuremapMvc.cs 添加到App_Start 文件夹。
然后我创建了Filters 文件夹，并为其添加了一个属性、一个操作过滤器和一个过滤器提供程序类：

我的属性类 - LogActionsAttribute - 是最简单的。 它只是一个属性，没有任何操作的引用：

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false)]
public class LogActionsAttribute : System.Attribute
{
}

在Controller 上使用：

[LogActions]
public class HomeController : System.Web.Mvc.Controller
{
    public ActionResult Index()
    {
        return View();
    }
}

现在我需要添加一个动作过滤器来寻找这个属性并做一些事情。在我的例子中，记录传入的参数和执行结果。 ILog 是一个自定义接口，其中包含此过滤器使用的这两种方法。

ControllerLoggerFilter类：

public class ControllerLoggerFilter : IActionFilter
{
    private readonly ILog _log;
    private string _request;

    public ControllerLoggerFilter(ILog log)
    {
        _log = log;
    }

    public void OnActionExecuting(ActionExecutingContext filterContext)
    {
        if (ApplyBehavior(filterContext))
        {
            ActionExecuting(filterContext);
        }
    }

    public void OnActionExecuted(ActionExecutedContext filterContext)
    {
        if (ApplyBehavior(filterContext))
        {
            ActionExecuted(filterContext);
        }
    }

    private void ActionExecuting(ControllerContext c)
    {
        if (c == null || c.HttpContext == null)
            return;

        _log.LogInput(c.HttpContext.Request);
        _request = c.HttpContext.Request;
    }

    private void ActionExecuted(ControllerContext c)
    {
        if (c.HttpContext.Response == null)
            return;

        _log.LogOutput(_request, c.HttpContext.Response);
    }

    private static bool ApplyBehavior(ActionExecutingContext filterContext)
    {
        return
            filterContext.ActionDescriptor.ControllerDescriptor
.GetCustomAttributes(typeof (LogActionsAttribute),
                false).Any();
    }

    private static bool ApplyBehavior(ActionExecutedContext filterContext)
    {
        return
            filterContext.ActionDescriptor.ControllerDescriptor
.GetCustomAttributes(typeof (LogActionsAttribute),
                false).Any();
    }
}

我现在必须告诉 MVC，这个过滤器需要在管道中。由于它是由结构映射容器构建的，我需要一个自定义的IFilterProvider：

public class MvcInjectableFilterProvider : IFilterProvider
{
    private readonly IEnumerable<Filter> _list;

    public MvcInjectableFilterProvider(IContainer container)
    {
        _list = GetContainerFilters(container);
    }

    public IEnumerable<Filter> GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
    {
        return _list;
    }

    private static IEnumerable<Filter> GetContainerFilters(IContainer container)
    {
        return
            container.GetAllInstances<IActionFilter>()
                .Select(instance => new Filter(instance, FilterScope.Action, null));
    }
}

最后一件事：在我的IoC.cs 中注册我的课程。
这是我在安装 NuGet 包时创建的文件中唯一需要修改的地方。

public static class IoC {
    public static IContainer Initialize() {
        return new Container(c =>
        {
            c.AddRegistry<DefaultRegistry>();
            // added these lines:
            c.For<ILog>().Use<Log>();
            c.For<IActionFilter>().Use<ControllerLoggerFilter>();
            c.For<IFilterProvider>().Use<MvcInjectableFilterProvider>();
        });
    }
}

来源：
Mark Seemann（以及其他地方）
Javier G. Lozano
eric.sowell
K. Scott Allen

Answer 2

亲爱的朋友们，我解决了我的问题，我的 LogAttribute 类的 setter 属性中缺少 [SetterProperty]

    public class LogAttribute : ActionFilterAttribute
{
    [SetterProperty]
    public ApplicationDbContext Context { get; set; }
    public string Description { get; set; }
    public LogAttribute(string description)
    {
        Description = description;
    }

    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        var userId = filterContext.HttpContext.User.Identity.GetUserId();
        var user = Context.Users.Find(userId);
        Context.Logs.Add(new Log(user, filterContext.ActionDescriptor.ActionName,
                                filterContext.ActionDescriptor.ControllerDescriptor.ControllerName,
                                Description
                                )
                        );
        Context.SaveChanges();
    }
}

现在它的工作:)

Answer 3

在 ActionFilters 中使用 setter 属性是一个非常糟糕的主意！ 同一个 actionFilter 实例可以在多个请求之间共享。结果不同的请求（线程）将获得对 ApplicationDbContext 的相同引用。

Are ActionFilterAttributes reused across threads? How does that work?