add extension method for excluding the contents of one list from another.

fix UpdateUser to use Exclude rather than Except method for linq.
#98

DataCenter_Windows/WindowsDataCenter/SQLiteRepository/Extensions/Extensions.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SQLiteRepository.Extensions
+{
+    public static class EnumerableExtensions
+    {
+        public static IEnumerable<TSource> Exclude<TSource, TKey>(this IEnumerable<TSource> source,
+            IEnumerable<TSource> exclude, Func<TSource, TKey> keySelector)
+        {
+            var excludedSet = new HashSet<TKey>(exclude.Select(keySelector));
+            return source.Where(item => !excludedSet.Contains(keySelector(item)));
+        }
+    }
+}

DataCenter_Windows/WindowsDataCenter/SQLiteRepository/SQLiteRepository.cs

@@ -9,6 +9,7 @@ using Interfaces;
 using SQLite.Net;
 using SQLite.Net.Platform.Win32;
 using SQLiteRepository.Converters;
+using SQLiteRepository.Extensions;
 using SQLiteRepository.Properties;
 
 namespace SQLiteRepository
@@ -241,12 +242,11 @@ namespace SQLiteRepository
         public OperationResponse UpdateUser(User user, out int userIdResult)
         {
             var ret = OperationResponse.NONE;
-
             //Get a list of current associated identifiers, convert into a list of Identifier Objects..
             var currentCards =
                 _connection.Query<CardUniqueId>(SQLiteProcedures.GET_CARDS_BY_USER_ID, user.UserId)
-                    .Select(IdentifierConverter.ConvertToIdentifierDto);
+                    .Select(IdentifierConverter.ConvertToIdentifierDto).ToList();
-            var cardsToRemove = currentCards.Except(user.AssociatedIdentifiers).Select(x => x.Id).ToList();
+            var cardsToRemove = currentCards.Exclude(user.AssociatedIdentifiers, x => x.Id).Select(x => x.Id).ToList();
             
             #region Update/Create User
             int userId;
@@ -885,6 +885,5 @@ namespace SQLiteRepository
                 userId
             );
         }
-
     }
 }

DataCenter_Windows/WindowsDataCenter/SQLiteRepository/SQLiteRepository.csproj

@@ -83,6 +83,7 @@
     <Compile Include="Converters\TimeLogConverter.cs" />
     <Compile Include="Converters\UserConverter.cs" />
     <Compile Include="DBVersion.cs" />
+    <Compile Include="Extensions\Extensions.cs" />
     <Compile Include="GroupDb.cs" />
     <Compile Include="LogSourceDb.cs" />
     <Compile Include="SQLiteRepository.cs" />