Load memberships

lib/models/friend.dart

@@ -22,8 +22,6 @@ class Friend extends CacheModel implements Comparable<Friend> {
   })  : assert(id != null),
         assert(accepted != null),
         assert(lastActive != null),
-        assert(following != null),
-        assert(canPostTexts != null),
         super(id: id);
 
   /// Check out whether friend is connected or not

lib/models/membership.dart

@@ -0,0 +1,38 @@
+import 'package:comunic/models/conversation.dart';
+import 'package:comunic/models/friend.dart';
+import 'package:flutter/material.dart';
+
+/// Membership information
+///
+/// @author Pierre Hubert
+
+enum MembershipType { FRIEND, GROUP, CONVERSATION }
+
+class Membership {
+  final MembershipType type;
+  final Conversation conversation;
+  final Friend friend;
+  final int groupID;
+  final int groupLastActive;
+
+  Membership.conversation(this.conversation)
+      : type = MembershipType.CONVERSATION,
+        friend = null,
+        groupID = null,
+        groupLastActive = null,
+        assert(conversation != null);
+
+  Membership.friend(this.friend)
+      : type = MembershipType.FRIEND,
+        conversation = null,
+        groupID = null,
+        groupLastActive = null,
+        assert(friend != null);
+
+  Membership.group({@required this.groupID, @required this.groupLastActive})
+      : type = MembershipType.GROUP,
+        conversation = null,
+        friend = null,
+        assert(groupID != null),
+        assert(groupLastActive != null);
+}