MOSS: SPListItem.Update() throws error Operation is not valid due to the current state of the object.

问题:

在SPSecurity.RunWithElevatedPrivileges 代码块中执行SPListItem.Update()，

SPSecurity.RunWithElevatedPrivileges

                (

                    () =>

                    {

                        using (SPSite site = new SPSite("web url"))

                        {

                            using (var tempWeb = site.OpenWeb())

                            {

                                var list = tempWeb.Lists["mylist"];

                                var Item = list.Items[0];

                                Item["Title"] = "new Title";

                                Item.Update();

                            }

                        }

                    }

                ); 

将会得到如下错误：Operation is not valid due to the current state of the object.

 解决此问题有两个办法：

1。Item.Update();放到SPSecurity.RunWithElevatedPrivileges语句块的外面。

SPListItem Item = null;                

      SPSecurity.RunWithElevatedPrivileges

                (

                    () =>

                    {

                        using (SPSite site = new SPSite("web url"))

                        {

                            using (var tempWeb = site.OpenWeb())

                            {

                                var list = tempWeb.Lists["mylist"];

                                Item = list.Items[0];                               

                            }

                        }

                    }

                );

      Item["Title"] = "new Title";

      Item.Update();

 详情可参考老外的原文：http://littletalk.wordpress.com/2009/04/03/moss-splistitemupdate-throws-error-operation-is-not-valid-due-to-the-current-state-of-the-object/

2. 第二个方法是在new SPSite(),SPWeb时不能Hard Code URL类似于以上的代码，

应该使用如下方式：

        var webContext = SPContext.Current.Web; 

        SPSecurity.RunWithElevatedPrivileges

                (

                    () =>

                    {

                        using (SPSite site = new SPSite(webContext.Site.ID))

                        {

                            using (var tempWeb = site.OpenWeb(webContext.ID))

                            {

                                var list = tempWeb.Lists["mylist"];

                                var Item = list.Items[0];

 

                                Item["Title"] = "new Title";

                                Item.Update();

                            }

                        }

                    }

                );

但是此方法有一个问题：在非Web应用程序的中，如控制台程序，以上代码将出现错误，因为SPContext.Current.Web为Null。

 详情可参考老外的原文：http://vspug.com/ssa/2007/11/25/operation-is-not-valid-due-to-the-current-state-of-the-object/