异常“项目已被添加。”在MetaModel.Register中

Question

我的Global.asax包含以下代码：

public class Global : System.Web.HttpApplication
    {
        private MetaModel _s_Model = new AdvancedMetaModel();
        public MetaModel s_Model
        {
            get
            {
                return _s_Model;
            }
        }

        private MetaModel _a_Model = new AdvancedMetaModel();
        public MetaModel a_Model
        {
            get
            {
                return _a_Model;
            }
        }

        public void RegisterRoutes(RouteCollection routes)
        {
            Dictionary<Helper.ModelName, MetaModel> registeredRoutes = new Dictionary<Helper.ModelName, MetaModel>();

            if (SQLAppModel.ModelQuery.GetUserType() == Utility.Helper.UserType.ApplicationAdmin
                || SQLAppModel.ModelQuery.GetUserType() == Utility.Helper.UserType.SystemAdmin)
            {
                _a_Model.RegisterContext(typeof(SQLAppModel.aEntities), new ContextConfiguration() { ScaffoldAllTables = true });

                /** Full Permission **/
                routes.Add(new DynamicDataRoute("{table}/ListDetails.aspx")
                {
                    Action = PageAction.List,
                    ViewName = "ListDetails",
                    Model = a_Model
                });

                routes.Add(new DynamicDataRoute("{table}/ListDetails.aspx")
                {
                    Action = PageAction.Details,
                    ViewName = "ListDetails",
                    Model = a_Model
                });

                registeredRoutes.Add(Helper.ModelName.Administration, a_Model);
            }

            string supportedEnvironments = System.Configuration.ConfigurationManager.AppSettings[Helper.SupportedEnvironmentsAppSettingsKey].ToString();

            foreach (string supportedEnvironment in supportedEnvironments.Split(','))
            {

                foreach (var supportedSystem in SQLAppModel.ModelQuery.GetSupportedSystems(supportedEnvironment, true))
                {
                    if (supportedEnvironment.ToUpper() == "ORACLE")
                    {
                        if (supportedSystem.Name.ToUpper() == "ADS")
                        {
                            _s_model.RegisterContext(typeof(OracleAppModel.sEntities), new ContextConfiguration()
                            {
                                ScaffoldAllTables = true
                            });

                            routes.Add(new DynamicDataRoute("{table}/ReadOnlyListDetails.aspx")
                            {
                                Action = PageAction.List,
                                ViewName = "ReadOnlyListDetails",
                                Model = s_model
                            });

                            routes.Add(new DynamicDataRoute("{table}/ReadOnlyListDetails.aspx")
                            {
                                Action = PageAction.Details,
                                ViewName = "ReadOnlyListDetails",
                                Model = s_model
                            });
                            registeredRoutes.Add(Helper.ModelName.ADS, s_model);
                        }
                    }
                }

            HttpContext.Current.Session[Helper.RegisteredRouteListSessionKey] = registeredRoutes;
        }

        void Application_Start(object sender, EventArgs e)
        {

        }

        void Session_Start(object sender, EventArgs e)
        {
            SQLAppModel.ModelQuery.GetApplicationUser();
            RegisterRoutes(RouteTable.Routes);
        }
    }

当我第一次使用ASP.NET开发web服务器调试我的应用程序时，该应用程序运行良好，并给出了预期的结果。

但当我停止调试并再次启动它时，它给出了以下异常：

已添加项目。字典中的键:要添加的'APP.SQLAppModel.sEntities‘键：'APP.SQLAppModel.sEntities’

抛出此异常的行是_a_Model.RegisterContext(typeof(SQLAppModel.aEntities)，ContextConfiguration() { ScaffoldAllTables = true })；

完成堆栈跟踪：

ArgumentException:已添加项。字典中的键:正在添加的‘System.Web.DynamicData.MetaModel.RegisterContext(DataModelProvider’键：'APP.SQLAppModel.sEntities‘System.Collections.Hashtable.Insert(对象键，对象n值，布尔加法) +9352427 System.Collections.Hashtable.Add(对象键，对象值) +11 System.Web.DynamicData.MetaModelManager.AddModel(Type contextType，MetaModel型号) +96 System.Web.DynamicData.MetaModel.RegisterContext(Func`1 dataModelProvider，ContextConfiguration配置)+727value contextFactory，ContextConfiguration配置) +390 System.Web.DynamicData.MetaModel.RegisterContext(Type contextFactory，ContextConfiguration contextType，ContextConfiguration配置) +8955827 System.Web.SessionState.SessionStateModule.CompleteAcquireState() +148 System.Web.SessionState.SessionStateModule.BeginAcquireState(Object源，EventArgs e，AsyncCallback cb，C：\Anand\SAMI\Global.asax.cs:137 SAMI.Global.Session_Start(对象发送者，EventArgs e)中的C：\Anand\SAMI\Global.asax.cs:137路由(EventArgs路由)，对象步长) +561 System.Web.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +96 System.Web.HttpApplication.ExecuteStep(IExecutionStep extraData，布尔值& completedSynchronously) +184

请让我知道如何解决这个问题。我很难发现问题所在。

Answer 1

问题是您从Session_Start调用RegisterRoutes，因此它可能会被多次调用。您需要从Application_Start调用它。