Web API，Web Service SharePoint對象操作報Operation is not valid due to the current state of the object解決方案

Web API，Web Service SharePoint對象操作報Operation is not valid due to the current state of the object解決方案，這是因為當前的user信息不一致導致的，添加HttpContext.Current = null;，解決，要類似這樣：

SPSecurity.RunWithElevatedPrivileges(delegate()
            {
                HttpContext.Current = null;
                using (SPSite site = new SPSite(targetWeb))
                {
                    using (SPWeb web = site.OpenWeb())
                    {
                        SPList targetlist = web.Lists[targetList];
                        foreach (ItemType item in import.item)
                        {
   ...
                        }
                    }
                }
            });