Flutter- FCM with Local notification and alert

Question

This is first time I am testing FCM with Flutter. I checked some of the SO questions and documents from GitHub.

I am able to send the notifications and they are getting delivered when the app is not running.

If app is running or in the background then messages are not visible.

I have added the code in main.dart file but not sure this is the correct way or not.

Edit: This is for onResume:

{notification: {}, data: {badge: 1, collapse_key: com.HT, google.original_priority: high, google.sent_time: 1623238, google.delivered_priority: high, sound: default, google.ttl: 2419200, from: 71374876, body: Body, title: Title, click_action: FLUTTER_NOTIFICATION_CLICK, google.message_id: 0:50a56}}

In the Below code, i am trying to use local notifications with FCM.

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final FirebaseMessaging _firebaseMessaging = FirebaseMessaging();
  FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
      new FlutterLocalNotificationsPlugin();

  @override
  void initState() {
    var initializationSettingsAndroid =
        new AndroidInitializationSettings('@mipmap/ic_launcher');
    var initializationSettingsIOS = new IOSInitializationSettings();
    var initializationSettings = new InitializationSettings(
        android: initializationSettingsAndroid, iOS: initializationSettingsIOS);
    flutterLocalNotificationsPlugin.initialize(initializationSettings,
        onSelectNotification: onSelectNotification);
    _firebaseMessaging.configure(
      onMessage: (Map<String, dynamic> message) async {
        showNotification(
            message['notification']['title'], message['notification']['body']);
        print("onMessage: $message");
      },
      onLaunch: (Map<String, dynamic> message) async {
        print("onLaunch: $message");
        // Navigator.pushNamed(context, '/notify');
        ExtendedNavigator.of(context).push(
          Routes.bookingQRScan,
        );
      },
      onResume: (Map<String, dynamic> message) async {
        print("onResume: $message");
      },
    );
  }

  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      debugShowCheckedModeBanner: false,
      home: AnimatedSplashScreen(), //SplashScreen()

      builder: ExtendedNavigator.builder<a.Router>(router: a.Router()),
    );
  }

  Future onSelectNotification(String payload) async {
    showDialog(
      context: context,
      builder: (_) {
        return new AlertDialog(
          title: Text("PayLoad"),
          content: Text("Payload : $payload"),
        );
      },
    );
  }

  void showNotification(String title, String body) async {
    await _demoNotification(title, body);
  }

  Future<void> _demoNotification(String title, String body) async {
    var androidPlatformChannelSpecifics = AndroidNotificationDetails(
        'channel_ID', 'channel name', 'channel description',
        importance: Importance.max,
        playSound: false, //true,
        //sound: 'sound',
        showProgress: true,
        priority: Priority.high,
        ticker: 'test ticker');

    //var iOSChannelSpecifics = IOSNotificationDetails();
    var platformChannelSpecifics =
        NotificationDetails(android: androidPlatformChannelSpecifics);
    await flutterLocalNotificationsPlugin
        .show(0, title, body, platformChannelSpecifics, payload: 'test');
  }
}

Error

This is when my app is running on foreground. E/FlutterFcmService(14434): Fatal: failed to find callback
W/FirebaseMessaging(14434): Missing Default Notification Channel metadata in AndroidManifest. Default value will be used.
W/ConnectionTracker(14434): Exception thrown while unbinding
W/ConnectionTracker(14434): java.lang.IllegalArgumentException: Service not registered: lu@fb04880
Notification is visible in notification center. Now i am clicking on it and app get terminated.
and new instance of app is running and below is the return code. I/flutter (14434): onResume: {notification: {}, data: {badge: 1, collapse_key: com.HT, google.original_priority: high, google.sent_time: 1607733798, google.delivered_priority: high, sound: default, google.ttl: 2419200, from: 774876, body: Body, title: Title, click_action: FLUTTER_NOTIFICATION_CLICK, google.message_id: 0:1607573733816296%850a56}}
E/FlutterFcmService(14434): Fatal: failed to find callback
W/ConnectionTracker(14434): Exception thrown while unbinding

Edit 2: I did more digging and come up with the below code.

final FirebaseMessaging _fcm = FirebaseMessaging();

  FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
      FlutterLocalNotificationsPlugin();

  var initializationSettingsAndroid;
  var initializationSettingsIOS;
  var initializationSettings;

  void _showNotification() async {
    //await _buildNotification();
  }

  Future<dynamic> myBackgroundMessageHandler(Map<String, dynamic> message) {
    if (message.containsKey('data')) {
      // Handle data message
      final dynamic data = message['data'];
    }

    if (message.containsKey('notification')) {
      // Handle notification message

      final dynamic notification = message['notification'];
    }

    // Or do other work.
  }

  Future<void> _createNotificationChannel(
      String id, String name, String description) async {
    final flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();
    var androidNotificationChannel = AndroidNotificationChannel(
      id,
      name,
      description,
      importance: Importance.max,
      playSound: true,
      // sound: RawResourceAndroidNotificationSound('not_kiddin'),
      enableVibration: true,
    );
    await flutterLocalNotificationsPlugin
        .resolvePlatformSpecificImplementation<
            AndroidFlutterLocalNotificationsPlugin>()
        ?.createNotificationChannel(androidNotificationChannel);
  }

  Future<void> _buildNotification(String title, String body) async {
    var androidPlatformChannelSpecifics = AndroidNotificationDetails(
        'my_channel', 'Channel Name', 'Channel Description.',
        importance: Importance.max,
        priority: Priority.high,
        //  playSound: true,
        enableVibration: true,
        //  sound: RawResourceAndroidNotificationSound('not_kiddin'),
        ticker: 'noorderlicht');
    //var iOSChannelSpecifics = IOSNotificationDetails();
    var platformChannelSpecifics =
        NotificationDetails(android: androidPlatformChannelSpecifics);

    await flutterLocalNotificationsPlugin
        .show(0, title, body, platformChannelSpecifics, payload: 'payload');
  }

  @override
  void initState() {
    super.initState();

    initializationSettingsAndroid =
        AndroidInitializationSettings('@mipmap/ic_launcher');
    initializationSettingsIOS = IOSInitializationSettings(
        onDidReceiveLocalNotification: onDidReceiveLocalNotification);

    initializationSettings =
        InitializationSettings(android: initializationSettingsAndroid);
    // initializationSettingsAndroid, initializationSettingsIOS);

    _fcm.requestNotificationPermissions();

    _fcm.configure(
      onMessage: (Map<String, dynamic> message) async {
        print(message);
        flutterLocalNotificationsPlugin.initialize(initializationSettings,
            onSelectNotification: onSelectNotification);

        //_showNotification();
        Map.from(message).map((key, value) {
          print(key);
          print(value);
          print(value['title']);
          _buildNotification(value['title'], value['body']);
        });
      },
      onLaunch: (Map<String, dynamic> message) async {
        print("onLaunch: $message");
      },
      onResume: (Map<String, dynamic> message) async {
        print("onResume: $message");
        print(message['data']['title']);
        //AlertDialog(title: message['data']['title']);
        ExtendedNavigator.of(context).push(
          Routes.bookingQRScan,
        );
        //_showNotification();
      },
    );
  }

  Future onDidReceiveLocalNotification(
      int id, String title, String body, String payload) async {
    // display a dialog with the notification details, tap ok to go to another page
    showDialog(
      context: context,
      builder: (BuildContext context) => CupertinoAlertDialog(
        title: Text(title),
        content: Text(body),
        actions: [
          CupertinoDialogAction(
            isDefaultAction: true,
            child: Text('Ok'),
            onPressed: () {},
          )
        ],
      ),
    );
  }

  Future onSelectNotification(String payload) async {
    if (payload != null) {
      debugPrint('Notification payload: $payload');
    }
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      debugShowCheckedModeBanner: false,
      home: AnimatedSplashScreen(), //SplashScreen()

      builder: ExtendedNavigator.builder<a.Router>(router: a.Router()),
    );
  }

With above code i can see notifications in notification bar but onresume section i want to redirection that is not working. Not sure why.

Also I want to show alert box in onmeesage and onresume events.

Answer 1

Your payload must be correct, notification and data object inside the payload must contain the title and body key. you will get title and body null when your app is closed in notification key in that situation you should have title and body in the side data key.

{notification: {title: title, body: test}, data: {notification_type: Welcome, body: body, badge: 1, sound: , title: farhana mam, click_action: FLUTTER_NOTIFICATION_CLICK, message: H R U, category_id: 2, product_id: 1, img_url: }}

and don't put title and body null

void showNotification(Map<String, dynamic> msg) async {
    //{notification: {title: title, body: test}, data: {notification_type: Welcome, body: body, badge: 1, sound: , title: farhana mam, click_action: FLUTTER_NOTIFICATION_CLICK, message: H R U, category_id: 2, product_id: 1, img_url: }}
    print(msg);
    print(msg['data']['title']);
    var title = msg['data']['title'];
    var msge = msg['data']['body'];

    var android = new AndroidNotificationDetails(
        'channel id', 'channel NAME', 'CHANNEL DESCRIPTION',
        priority: Priority.High, importance: Importance.Max);
    var iOS = new IOSNotificationDetails();
    var platform = new NotificationDetails(android, iOS);
    await flutterLocalNotificationsPlugin.show(0, title, msge, platform,
        payload: msge);
  }

for redirection

FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin = new FlutterLocalNotificationsPlugin();
    var android = new AndroidInitializationSettings('@mipmap/ic_launcher');
    var iOS = new IOSInitializationSettings();
    var initSetttings = new InitializationSettings(android, iOS);
    flutterLocalNotificationsPlugin.initialize(initSetttings, onSelectNotification: onSelectNotification);
    firebaseCloudMessaging_Listeners();

  Future onSelectNotification(String payload) async {
    if (payload != null) {
      debugPrint('notification payload:------ ${payload}');
      await Navigator.push(
        context,
        new MaterialPageRoute(builder: (context) => NotificationListing()),
      ).then((value) {});
    }

  }

in 'onSelectNotification' you can pass your condition in string parama and you can redirect

(optional, but recommended) If want to be notified in your app (via onResume and onLaunch, see below) when the user clicks on a notification in the system tray include the following intent-filter within the tag of your android/app/src/main/AndroidManifest.xml:

Answer 2

Looking at your (last edited) code above, I think first you have to make sure, whether localnotifications is used or the default fcm one. Since your myBackgroundMessageHandler does not do anything, I assume the latter one. Try replacing the title temporarily with a fixed string (e.g. "this is a local one") to make sure.

Secondly, myBackgroundMessageHandler will only be called for data messages. If you use the payload you wrote in the beginning, you should be fine. Anyway make sure to not put title, body, style-information etc directly in the payload. If you need it, put it in the data node.

This is the code I am using:

calling the notificationService init() method in main.dart

notification-service.dart

import 'package:flutter_dotenv/flutter_dotenv.dart';
import 'package:app/models/data-notification.dart';
import 'dart:async';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:http/http.dart' as http;
import 'package:path_provider/path_provider.dart';
import 'dart:io';

FlutterLocalNotificationsPlugin notificationsPlugin =
    FlutterLocalNotificationsPlugin();

//Function to handle Notification data in background. 
Future<dynamic> backgroundMessageHandler(Map<String, dynamic> message) {
  print("FCM backgroundMessageHandler $message");
  showNotification(DataNotification.fromPushMessage(message['data']));
  return Future<void>.value();
}

//Function to handle Notification Click.
Future<void> onSelectNotification(String payload) {
  print("FCM onSelectNotification");
  return Future<void>.value();
}

//Function to Parse and Show Notification when app is in foreground
Future<dynamic> onMessage(Map<String, dynamic> message) {
  print("FCM onMessage $message");
  showNotification(DataNotification.fromPushMessage(message['data']));
  return Future<void>.value();
}

//Function to Handle notification click if app is in background
Future<dynamic> onResume(Map<String, dynamic> message) {
  print("FCM onResume $message");
  return Future<void>.value();
}

//Function to Handle notification click if app is not in foreground neither in background
Future<dynamic> onLaunch(Map<String, dynamic> message) {
  print("FCM onLaunch $message");
  return Future<void>.value();
}

void showNotification(DataNotification notification) async {
  final AndroidNotificationDetails androidPlatformChannelSpecifics =
      await getAndroidNotificationDetails(notification);

  final NotificationDetails platformChannelSpecifics =
      NotificationDetails(android: androidPlatformChannelSpecifics);

  await notificationsPlugin.show(
    0,
    notification.title,
    notification.body,
    platformChannelSpecifics,
  );
}

Future<AndroidNotificationDetails> getAndroidNotificationDetails(
    DataNotification notification) async {
  switch (notification.notificationType) {
    case NotificationType.NEW_INVITATION:
    case NotificationType.NEW_MEMBERSHIP:
    case NotificationType.NEW_ADMIN_ROLE:
    case NotificationType.MEMBERSHIP_BLOCKED:
    case NotificationType.MEMBERSHIP_REMOVED:
    case NotificationType.NEW_MEMBERSHIP_REQUEST:
      return AndroidNotificationDetails(
          'organization',
          'Organization management',
          'Notifications regarding your organizations and memberships.',
          importance: Importance.max,
          priority: Priority.high,
          showWhen: false,
          category: "Organization",
          icon: 'my_app_icon_simple',
          largeIcon: DrawableResourceAndroidBitmap('my_app_icon'),
          styleInformation: await getBigPictureStyle(notification),
          sound: RawResourceAndroidNotificationSound('slow_spring_board'));
    case NotificationType.NONE:
    default:
      return AndroidNotificationDetails('general', 'General notifications',
          'General notifications that are not sorted to any specific topics.',
          importance: Importance.max,
          priority: Priority.high,
          showWhen: false,
          category: "General",
          icon: 'my_app_icon_simple',
          largeIcon: DrawableResourceAndroidBitmap('my_app_icon'),
          styleInformation: await getBigPictureStyle(notification),
          sound: RawResourceAndroidNotificationSound('slow_spring_board'));
  }
}

Future<BigPictureStyleInformation> getBigPictureStyle(
    DataNotification notification) async {
  if (notification.imageUrl != null) {
    print("downloading");
    final String bigPicturePath =
        await _downloadAndSaveFile(notification.imageUrl, 'bigPicture');

    return BigPictureStyleInformation(FilePathAndroidBitmap(bigPicturePath),
        hideExpandedLargeIcon: true,
        contentTitle: notification.title,
        htmlFormatContentTitle: false,
        summaryText: notification.body,
        htmlFormatSummaryText: false);
  } else {
    print("NOT downloading");
    return null;
  }
}

Future<String> _downloadAndSaveFile(String url, String fileName) async {
  final Directory directory = await getApplicationDocumentsDirectory();
  final String filePath = '${directory.path}/$fileName';
  final http.Response response = await http.get(url);
  final File file = File(filePath);
  await file.writeAsBytes(response.bodyBytes);
  return filePath;
}

class NotificationService {

  FirebaseMessaging _fcm = FirebaseMessaging();

  void init() async {
    final AndroidInitializationSettings initializationSettingsAndroid =
        AndroidInitializationSettings('app_icon');

    final IOSInitializationSettings initializationSettingsIOS =
        IOSInitializationSettings();

    final InitializationSettings initializationSettings =
        InitializationSettings(
      android: initializationSettingsAndroid,
      iOS: initializationSettingsIOS,
    );

    await notificationsPlugin.initialize(initializationSettings,
        onSelectNotification: (value) => onSelectNotification(value));

    _fcm.configure(
      onMessage: onMessage,
      onBackgroundMessage: backgroundMessageHandler,
      onLaunch: onLaunch,
      onResume: onResume,
    );
  }
}

data-notification.dart

import 'package:enum_to_string/enum_to_string.dart';

class DataNotification {
  final String id;
  final String title;
  final String body;
  final NotificationType notificationType;
  final String imageUrl;
  final dynamic data;
  final DateTime readAt;
  final DateTime createdAt;
  final DateTime updatedAt;

  DataNotification({
    this.id,
    this.title,
    this.body,
    this.notificationType,
    this.imageUrl,
    this.data,
    this.readAt,
    this.createdAt,
    this.updatedAt,
  });

  factory DataNotification.fromPushMessage(dynamic data) {
    return DataNotification(
      id: data['id'],
      title: data['title'],
      body: data['body'],
      notificationType: EnumToString.fromString(
          NotificationType.values, data['notification_type']),
      imageUrl: data['image_url'] ?? null,
      data: data,
      readAt: null,
      createdAt: null,
      updatedAt: null,
    );
  }
}

enum NotificationType {
  NONE,
  NEW_INVITATION,
  NEW_MEMBERSHIP,
  NEW_ADMIN_ROLE,
  MEMBERSHIP_BLOCKED,
  MEMBERSHIP_REMOVED,
  NEW_MEMBERSHIP_REQUEST
}

You can ignore the DataNotification model part, and parse the notification yourself, I just used it for some additional interactions with in the backend.

This works well for me, however, if you want to show an alert for "onSelectNotification" or alike, you need to find a way to get the context there. Not (yet) sure, how to do that.

EDIT: You can call it like this in main.dart

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  NotificationService().init();

  runApp(
    MyApp()
  );
}

Be aware that there is currently an issue with backgroundmessaging and hot-reloading: https://github.com/FirebaseExtended/flutterfire/issues/4316