Removing permissions from a Sharepoint list item

I recently came across an interesting problem while working on an Infopath form.  As part of the submission process, I needed to remove all the permissions from my new document.  This seemed easy to do using by calling Item.BreakRoleInheritence = true and then removing all the existing permissions from the item.

 

When I published my form, I found that my approach generated an error: An exception of type 'System.UnauthorizedAccessException' occurred in Microsoft.SharePoint.dll but was not handled in user code. Additional information: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))

This error occured for any user who had Contribute access to the form library. 

 

After a bit of searching, I found this article: http://social.msdn.microsoft.com/Forums/en-US/sharepointdevelopment/thread/c3d2b304-7fcc-40d2-86ce-61d9b21b03d7  Look for the reply made by Kjetil Gullen on July 27.

 

The answer lies with how the .BreakRoleInheritence interacts with web.AllowUnsafeUpdates = true.  I won't go into the full explanation as the poster does an excellent job, but below is a code snippet that shows how to do this correctly.

 

                SPSecurity.RunWithElevatedPrivileges(delegate()

                    {

                        SPWeb _webInUserContext = SPContext.Current.Web;

                        SPSite _siteInUserContext = SPContext.Current.Site;

                        Guid _webGuid = _webInUserContext.ID;

                        Guid _siteGuid = _siteInUserContext.ID;

 

                        using (SPSite _site = new SPSite(_siteGuid))

                        {

                            _site.AllowUnsafeUpdates = true;//Allow Unsafe Updates for the Site

                            SPWeb _web = _site.OpenWeb(_webGuid);

                            _web.AllowUnsafeUpdates = true;//Allow Unsafe Updates for the Web

                            SPList docList = _web.Lists["Requests"];

 

                            SPListItem itemListItem = docList.Items.GetItemById(itemListID);

                            itemListItem.Web.AllowUnsafeUpdates = true;//Web as referenced by the item

 

                            itemListItem.BreakRoleInheritance(true);//Break your inheritence

 

                            itemListItem.Web.AllowUnsafeUpdates = true;//Breaking inheritence resets

                                                                       //Unsafe Updates, reenable it

 

                            //Remove the permissions one by one

                            foreach (SPRoleAssignment spra in itemListItem.RoleAssignments)

                            {

                                spra.RoleDefinitionBindings.RemoveAll();

                                spra.Update();

                            }

                       

                        });}