SPItemEventReceiver
From WSSWiki
The SPItemEventReceiver class provides a way for developers to develop custom code around the events the occur on items within SharePoint.
Contents |
[edit] Example
The following is an example of an SPItemEventReceiver that strips an item of it's permissions and assigns the members and owners groups as the default.
NOTE: The ItemCheckedIn event is required because the document will remain checked out and only visible to the user if a document is uploaded into SharePoint via the Multiple File Upload screen, or via Explorer View and the library has been setup to require metadata.
public class BreakPermissionItemEventReceiver : SPItemEventReceiver
{
#region Declarations
private const string MemberGroup = "vti_associatemembergroup";
private const string OwnerGroup = "vti_associateownergroup";
#endregion
#region Overrides
public override void ItemAdded(SPItemEventProperties properties)
{
if (properties == null)
return;
if (properties.ListItem.Level != SPFileLevel.Checkout)
{
StripPermissions(properties);
}
base.ItemAdded(properties);
}
public override void ItemCheckedIn(SPItemEventProperties properties)
{
if (properties == null)
return;
var list = properties.ListItem;
if (list.Versions.Count == 1)
StripPermissions(properties);
base.ItemCheckedIn(properties);
}
#endregion
#region Methods
private void StripPermissions(SPItemEventProperties properties)
{
using (SPSite site = SecurityHelper.GetElevatedSite(properties.WebUrl))
{
using (SPWeb web = site.OpenWeb())
{
var item = web.Lists[properties.ListId].GetItemById(properties.ListItemId);
if (!item.HasUniqueRoleAssignments)
{
item.BreakRoleInheritance(false);
var group = web.SiteGroups.GetByID(int.Parse(web.Properties[OwnerGroup]));
var assignment = new SPRoleAssignment(group);
assignment.RoleDefinitionBindings.Add(web.RoleDefinitions.GetByType(SPRoleType.Administrator));
item.RoleAssignments.Add(assignment);
group = web.SiteGroups.GetByID(int.Parse(web.Properties[MemberGroup]));
assignment = new SPRoleAssignment(group);
assignment.RoleDefinitionBindings.Add(web.RoleDefinitions.GetByType(SPRoleType.Contributor));
item.RoleAssignments.Add(assignment);
item.RoleAssignments.RemoveById(site.SystemAccount.ID);
this.DisableEventFiring();
item.SystemUpdate(false);
this.EnableEventFiring();
}
}
}
}
#endregion
}
// Thanks to Daniel Larson for this helper.
public static class SecurityHelper
{
/// <summary>
/// Returns an SPSite object that has been elevated to the System Account privileges.
/// </summary>
/// <param name="url">URL of the site you want to return.</param>
/// <returns></returns>
public static SPSite GetElevatedSite(string url)
{
using (SPSite site = new SPSite(url))
{
var token = GetSystemToken(site);
return new SPSite(url, token);
}
}
private static SPUserToken GetSystemToken(SPSite site)
{
site.CatchAccessDeniedException = false;
try
{
return site.SystemAccount.UserToken;
}
catch (UnauthorizedAccessException)
{
SPUserToken token = null;
SPSecurity.RunWithElevatedPrivileges(delegate()
{
using (SPSite elevatedSite = new SPSite(site.ID))
{
token = elevatedSite.SystemAccount.UserToken;
}
});
return token;
}
finally
{
site.CatchAccessDeniedException = true;
}
}
}
