Unauthorized exception with SPSecurity.RunWithElevatedPrivileges? - sharepoint

Question

I'm checking, if a given user is part of a group by this code below. I'm getting
unauthorized exception
(0x80070005)
and I do not understand why? I'm using SPSecurity.RunWithElevatedPrivileges, so why it is giving me this exception!? Anybody a hint for me? Thanks in advance!
public bool IsUserInGroup(SPWeb web, string groupName, string user)
{
try
{
bool returnValue = false;
SPSecurity.RunWithElevatedPrivileges(() =>
{
if (web.Groups.OfType<SPGroup>().Where(g => g.Name == groupName).Count() > 0)
{
SPGroup spGroup = web.Groups[groupName];
if (spGroup.Users.OfType<SPUser>().Where(u => u.LoginName.Equals(user)).Count() > 0)
{
returnValue = true;
}
else
{
returnValue = false;
}
}
else
{
returnValue = false;
}
});
return returnValue;
}
catch (Exception exp)
{
Classes.Logs.Error.Log_Error("IsUserInGroup", "DocumentCenterItem.cs", exp.Message, DateTime.Now);
return false;
}
}

Answer 1

You need to create a new instance of SP Web inside elevated privileges. In your current implementation, you are reusing the web object which runs in current user context.
So, try and modify the below code as per your requirement :
public bool IsUserInGroup(SPWeb web, string groupName, string user)
{
try
{
bool returnValue = false;
SPSecurity.RunWithElevatedPrivileges(() =>
{
using(SPSite site = new SPSite(web.Site.ID))
{
using(SPWeb elevatedWeb = site.OpenWeb(web.ID))
{
if (elevatedWeb.Groups.OfType<SPGroup>().Where(g => g.Name == groupName).Count() > 0)
{
SPGroup spGroup = elevatedWeb.Groups[groupName];
if (spGroup.Users.OfType<SPUser>().Where(u => u.LoginName.Equals(user)).Count() > 0)
{
returnValue = true;
}
else
{
returnValue = false;
}
}
else
{
returnValue = false;
}
}
}
});
return returnValue;
}
catch (Exception exp)
{
Classes.Logs.Error.Log_Error("IsUserInGroup", "DocumentCenterItem.cs", exp.Message, DateTime.Now);
return false;
}
}