Do not use SQLite anymore for users

lib/helpers/serialization/base_serialization_helper.dart

@@ -102,6 +102,8 @@ abstract class BaseSerializationHelper<T extends SerializableElement> {
     return _cache.any((element) => isContained(element));
   }
 
+  Future<bool> has(T el) => any((t) => t == el);
+
   /// Check if any entry in the last match the predicate
   Future<T> first(bool filter(T t)) async {
     await _loadCache();
@@ -120,10 +122,26 @@ abstract class BaseSerializationHelper<T extends SerializableElement> {
     await _saveCache();
   }
 
+  /// Insert or replace many elements
+  Future<void> insertOrReplaceElements(List<T> list) async {
+    await _loadCache();
+
+    _cache.removeWhere((element) => list.any((newEl) => element == newEl));
+    _cache.addAll(list);
+
+    await _saveCache();
+  }
+
   /// Remove elements
   Future<void> removeElement(bool isToRemove(T t)) async {
     await _loadCache();
     _cache.removeWhere((element) => isToRemove(element));
     await _saveCache();
   }
+
+  /// Remove all elements
+  Future<void> removeAll() async {
+    _cache = [];
+    await _saveCache();
+  }
 }

lib/helpers/serialization/user_list_serialization_helper.dart

@@ -0,0 +1,28 @@
+import 'package:comunic/helpers/serialization/base_serialization_helper.dart';
+import 'package:comunic/models/user.dart';
+
+/// User serialization helper
+///
+/// @author Pierre Hubert
+
+UsersListSerialisationHelper _singleton;
+
+class UsersListSerialisationHelper extends BaseSerializationHelper<User> {
+  UsersListSerialisationHelper._();
+
+  factory UsersListSerialisationHelper() {
+    if (_singleton == null) _singleton = UsersListSerialisationHelper._();
+
+    return _singleton;
+  }
+
+  @override
+  String get type => "users-list";
+
+  @override
+  User parse(Map<String, dynamic> m) => User.fromJson(m);
+
+  /// Remove a user by its ID
+  Future<void> removeUserByID(int userID) =>
+      removeElement((t) => t.id == userID);
+}