20131125-程式-多筆List資料取聯集

這是前一陣子寫的程式，一時想找還找不太到....記錄一下：

關鍵：Linq 的 Aggregate (合計)

            //將互斥的roleId 由IEnumerable<HashSet<string>> 轉換成 HashSet<string> //Union後的RoleIds  參考:http://goo.gl/5rl0LY
            var listOfLists = AllRoleMutexs.Value.Where(m => m.Mutex.RoleIds.Contains(relation.RoleID)).Select(m => m.Mutex.RoleIds);
            if (listOfLists.Any())
            {
                var mutexRoleIds = listOfLists.Skip(1)
                     .Aggregate(new HashSet<string>(listOfLists.First()),
                           (h, e) => { h.UnionWith(e); return h; });//取聯集
                var relationChecks = ServiceFactory.SecModifier.GetRoleRelationByAccountAndRoleIds(relation.AccountID, mutexRoleIds.ToArray());
                if (relationChecks.Any())
                {
                    throw new ArgumentException(string.Format("此[{0}]角色 與目前帳號[{2}]存在的[{1}]角色互斥，無法建立關聯", relation.RoleID, string.Join(",", relationChecks.Select(m => m.RoleID)), relation.AccountID));
                }
            }