Orchard CMS _workContextAccessor.GetContext（）。CurrentUser总是为空吗？

Question

我正在尝试使用以下代码捕获并检查用户的授权;注意， 除了我的标题问题，我不满意我如何在每个班级注入两项服务[也许是罪魁祸首]：

using System.Collections.Generic;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;
using Orchard;
using Orchard.Mvc.Routes;
using Orchard.Security;

namespace Orc.PP.Routes
{
    public class ProfileRoutes : IRouteProvider {
        private readonly IMembershipService _membershipService;
        private readonly IOrchardServices _orchardServices;

        public ProfileRoutes(IMembershipService membershipService, IOrchardServices orchardServices)
        {
            _membershipService = membershipService;
            _orchardServices = orchardServices;
        }

        public void GetRoutes(ICollection<RouteDescriptor> routes) {
            foreach (var routeDescriptor in GetRoutes())
                routes.Add(routeDescriptor);
        }

        public IEnumerable<RouteDescriptor> GetRoutes() {
            return new[] {
                // Note: Register/Edit have higher priority than Profile/{username} as 
                // Register / Edit could be interpreted as a username.

               new RouteDescriptor {
                   Priority = 7,
                   Route = new Route(
                       "Profile/Register",
                       new RouteValueDictionary {
                           {"area", "Orc.PP"},
                           {"controller", "Profile"},
                           {"action", "Register"}
                       },
                       new RouteValueDictionary (),
                       new RouteValueDictionary {
                           {"area", "Orc.PP"}
                       },
                       new MvcRouteHandler())
                },
                new RouteDescriptor {
                    Priority = 6,
                    Route = new Route(
                        "Profile/Edit",
                        new RouteValueDictionary {
                            {"area", "Orc.PP"},
                            {"controller", "Profile"},
                            {"action", "Edit"}
                        },
                        new RouteValueDictionary (),
                        new RouteValueDictionary {
                            {"area", "Orc.PP"}
                        },
                        new MvcRouteHandler())

                },
                new RouteDescriptor {
                    Priority = 5,
                    Route = new Route(
                        "PP/Profile/{username}",
                        new RouteValueDictionary {
                            {"area", "Orc.PP"},
                            {"controller", "Profile"},
                            {"action", "Index"},
                            //{"username", new UserNameConstraint() }//UrlParameter.Optional }
                        },
                        new RouteValueDictionary {//} (),
                            {"username",  new UserNameConstraint(_membershipService, _orchardServices)}
                        },
                        new RouteValueDictionary {
                            {"area", "Orc.PP"}
                        },
                        new MvcRouteHandler())
                }
            };
        }

        public class UserNameConstraint : IRouteConstraint
        {
            private readonly IMembershipService _membershipService;
            private readonly IOrchardServices _orchardServices;

            public UserNameConstraint(IMembershipService membershipService, IOrchardServices orchardServices)
            {
                _membershipService = membershipService;
                _orchardServices = orchardServices;
            }

            public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
            {
                // Get the username from the url
                var username = values["username"].ToString().ToLower();
                // Check for a match (assumes case insensitive)
                IUser user = _membershipService.GetUser(username);
                //Does user exist and have permission to veiw Profile?
                if (user == null || !_orchardServices.Authorizer.Authorize(Permissions.ViewProfiles, user, null))
                {
                    return false;
                }
                return true;
            }
        }
    }
}

致电后：

!_orchardServices.Authorizer.Authorize(Permissions.ViewProfiles, user, null))

在Orchard / Security / Authorizer.cs中：

public bool Authorize(Permission permission, IContent content, LocalizedString message)

其中

_workContextAccessor.GetContext().CurrentUser;

调用

，抛出错误：

NullReferenceException未被用户代码处理： {“对象引用未设置为对象的实例。”}

有人可以向我解释为什么/可能正确的方法来实现我正在尝试的东西吗？