“/BookShop”应用程序中的服务器错误。 序列不包含任何元素 说明: 执行当前 Web 请求期间,出现未处理的异常。请检查堆栈跟踪信息,以了解有关该错误以及代码中导致错误的出处的详细信息。 异常详细信息: System.InvalidOperationException: 序列不包含任何元素源错误: 行 22: treeView.Nodes.Clear(); ///清空树的所有节点 行 23: DataClassesDataContext db = new DataClassesDataContext(); 行 24: Category cat = db.Categories.Where(c => c.ParentID == -1).First(); 行 25: 行 26: ///创建根节点 源文件: c:/Inetpub/wwwroot/BookShop/App_Code/CategoryM.cs 行: 24 堆栈跟踪: [InvalidOperationException: 序列不包含任何元素] System.Data.Linq.SqlClient.SqlProvider.Execute(Expression query, QueryInfo queryInfo, IObjectReaderFactory factory, Object[] parentArgs, Object[] userArgs, ICompiledSubQuery[] subQueries, Object lastResult) +847 System.Data.Linq.SqlClient.SqlProvider.ExecuteAll(Expression query, QueryInfo[] queryInfos, IObjectReaderFactory factory, Object[] userArguments, ICompiledSubQuery[] subQueries) +113 System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query) +344 System.Data.Linq.DataQuery`1.System.Linq.IQueryProvider.Execute(Expression expression) +49 System.Linq.Queryable.First(IQueryable`1 source) +269 CategoryM.InitCategory(TreeView treeView, String sNodeUrl) in c:/Inetpub/wwwroot/BookShop/App_Code/CategoryM.cs:24 LeftTree.InitCategoryTree() in c:/Inetpub/wwwroot/BookShop/DesktopModules/LeftTree.aspx.cs:33 LeftTree.Page_Load(Object sender, EventArgs e) in c:/Inetpub/wwwroot/BookShop/DesktopModules/LeftTree.aspx.cs:26 System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14 System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35 System.Web.UI.Control.OnLoad(EventArgs e) +99 System.Web.UI.Control.LoadRecursive() +50 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627