Feed stream with changenotifier

lib/services/db_helper.dart

@@ -2,6 +2,8 @@ import 'package:flutter/foundation.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 import 'package:supabase_flutter/supabase_flutter.dart';
 
+import '../models/feed_item.dart';
+
 class DbHelper {
   static Future<SharedPreferences> get _prefs async =>
       SharedPreferences.getInstance();
@@ -58,9 +60,21 @@ class DbHelper {
     return false;
   }
 
+  static Future<List<FeedItem>> fetchFeed() async {
+    List<FeedItem> items = [];
+    final res = await _supabase.from('feed').select();
+    for (final map in res) {
+      items.add(FeedItem.fromMap(map));
+    }
+    return items;
+  }
+
   static void logout() async {
     final prefs = await _prefs;
     bool success = await prefs.remove('username');
     _supabase.auth.signOut();
   }
+
+  static Stream<List<Map<String, dynamic>>> get feedStream =>
+      _supabase.from('feed').stream(primaryKey: ['timestamp']);
 }

lib/services/feed_provider.dart

@@ -0,0 +1,36 @@
+import 'package:flutter/material.dart';
+import 'package:maggs_victory_voyage/services/db_helper.dart';
+
+import '../models/feed_item.dart';
+
+class Feed extends ChangeNotifier {
+  final List<FeedItem> _feed = [];
+  Stream? feedStream;
+
+  List<FeedItem> get feed {
+    if (feedStream == null) {
+      DbHelper.fetchFeed().then((value) {
+        _feed.clear();
+        _feed.addAll(value);
+      });
+      feedStream = DbHelper.feedStream;
+      feedStream!.listen(
+        (event) => _updateFeed(event),
+      );
+    }
+    return _feed;
+  }
+
+  void _updateFeed(List<Map<String, dynamic>> data) {
+    final List<FeedItem> newFeed =
+        data.map((e) => FeedItem.fromMap(e)).toList();
+
+    final newItems =
+        newFeed.where((element) => !_feed.contains(element)).toList();
+
+    if (newItems.isNotEmpty) {
+      _feed.addAll(newItems);
+      notifyListeners();
+    }
+  }
+}