c# - 如何将参数传递给 ASP.NET MVC 2 中的自定义 ActionFilter？

Question

我正在尝试创建一个自定义 ActionFilter，它对从 Controller 传递给它的一组参数进行操作。

到目前为止，我的客户 ActionFilter 看起来像这样:

public class CheckLoggedIn : ActionFilterAttribute
{
    public IGenesisRepository gr { get; set; }
    public Guid memberGuid { get; set; }

    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        Member thisMember = gr.GetActiveMember(memberGuid);
        Member bottomMember = gr.GetMemberOnBottom();

        if (thisMember.Role.Tier <= bottomMember.Role.Tier)
        {
            filterContext
                .HttpContext
                .Response
                .RedirectToRoute(new { controller = "Member", action = "Login" });
        }

        base.OnActionExecuting(filterContext);
    }
}

我知道我仍然需要检查空值等，但我不明白为什么 gr 和 memberGuid 没有成功传递。我这样称呼这个过滤器:

    [CheckLoggedIn(gr = genesisRepository, memberGuid = md.memberGUID)]
    public ActionResult Home(MemberData md)
    {
        return View(md);
    }

genesisRepository 和 md 正在 Controller 的构造函数中设置。

我无法编译它。我得到的错误是:

Error   1   'gr' is not a valid named attribute argument because it is not a valid attribute parameter type
Error   2   'memberGuid' is not a valid named attribute argument because it is not a valid attribute parameter type

我仔细检查了 gr 和 memberGuid 与 genesisRepority 和 md.memberGUID 的类型相同，什么是导致这些错误的原因吗？

解决方案

感谢 jfar 提供解决方案。

这是我最终使用的过滤器:

public class CheckLoggedIn : ActionFilterAttribute
{

    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        var thisController = ((MemberController)filterContext.Controller);

        IGenesisRepository gr = thisController.GenesisRepository;
        Guid memberGuid = ((MemberData)filterContext.HttpContext.Session[thisController.MemberKey]).MemberGUID;

        Member thisMember = gr.GetActiveMember(memberGuid);
        Member bottomMember = gr.GetMemberOnBottom();

        if (thisMember.Role.Tier >= bottomMember.Role.Tier)
        {
            filterContext.Result = new RedirectToRouteResult(
                new RouteValueDictionary(
                    new { 
                        controller = "Member", 
                        action = "Login" 
                    }));
        }

        base.OnActionExecuting(filterContext);
    }
}

Answer 1

这是实现此功能的一种方法。您可以从 ActionFilter 对象访问 ControllerContext 和 Controller。您需要做的就是将您的 Controller 转换为该类型，然后您就可以访问任何公共(public)成员。

给定这个 Controller :

public GenesisController : Controller
{
    [CheckLoggedIn()]
    public ActionResult Home(MemberData md)
    {
        return View(md);
    }
}

ActionFilter 看起来像

public class CheckLoggedIn : ActionFilterAttribute
{
    public IGenesisRepository gr { get; set; }
    public Guid memberGuid { get; set; }

    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        /* how to get the controller*/
        var controllerUsingThisAttribute = ((GenesisController)filterContext.Controller);

        /* now you can use the public properties from the controller */
        gr = controllerUsingThisAttribute .genesisRepository;
        memberGuid = (controllerUsingThisAttribute .memberGuid;

        Member thisMember = gr.GetActiveMember(memberGuid);
        Member bottomMember = gr.GetMemberOnBottom();

        if (thisMember.Role.Tier <= bottomMember.Role.Tier)
        {
            filterContext
                .HttpContext
                .Response
                .RedirectToRoute(new { controller = "Member", action = "Login" });
        }

        base.OnActionExecuting(filterContext);
    }
}

当然，这是假设 ActionFilter 未在多个 Controller 中使用，并且您可以接受耦合。另一种选择是创建一个具有共享属性的 ICheckedLoggedInController 接口(interface)，然后简单地转换为该接口(interface)。