Question

I have a Lookup that has a master list of priority levels and groups. Also, a List that has the groups an user is in. ILookup<int, string>, List<string>. I’d like to compare the List to ILookup and return the IGroupings that match the groups in the List. Then finally get the IGrouping with the higher priority (ex: returns 6 instead 3).

My issue is with the actual comparision of the List and ILookup. It seems I might have to use a for-loop. But I think I just haven’t found the right Linq statement(s) yet.

What I’ve tried below.

        List<string> groupsOfUser = whatGroupsUserBelongTo();
        ILookup<int, string> loginGroups = mapADToRole.SelectMany(ad => ad.Value
                                                                          .Select(grp => new {ad.Key, Value = grp}))
                                                      .ToLookup(adLkUp => adLkUp.Key, adLkUp => adLkUp.Value);


        var blah = loginGroups.Where(adGrp => adGrp.SelectMany(ad => groupsOfUser.Contains(ad)));

UPDATE:

mapADToRole is Dictionary<int, List<string>>. The code below works but using foreach loops.

        public static string getWindowsGroup()
        {
            List<string> groupsOfUser = whatGroupsUserBelongTo();
            ILookup<int, string> loginGroups = mapADToRole.SelectMany(ad => ad.Value
                                                                              .Select(grp => new {ad.Key, Value = grp}))
                                                          .ToLookup(adLkUp => adLkUp.Key, adLkUp => adLkUp.Value);



            List<IGrouping<int, string>> foo = new List<IGrouping<int, string>>();
            foreach (IGrouping<int, string> loginGroup in loginGroups)
            {
                foreach (var blah in loginGroup)
                {
                    if (groupsOfUser.Contains(blah))
                    {
                        foo.Add(loginGroup);
                    }
                }
            }

            var foobar = foo.Max(grp => grp.Key);
            return loginGroups[foobar].FirstOrDefault();

        }

Answer 1

I am not sure but this should do what your function does:

return mapADToRole.Where(item => item.Value.Any(groupsOfUser.Contains))
                  .OrderBy(item => item.Key)
                  .SelectMany(item => item.Value)
                  .FirstOrDefault();