Firebase: Registration token(s) provided to sendToDevice() must be a non-empty string or a non-empty array

Question

Using FCM to send push notification to my iOS device. Just couldn't get it to work. Managed to fetch the token but for some reason, it's not accepted by sendToDevice() The swift code seems to working okay receiving messages from Firebase Console. Please help! I just want a very simple push notification! A new order from a customer and the chef gets a push notification - with sound and badge preferably. Thanks everyone!

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

//register to onWrite event of my node news
exports.sendPushNotification = functions.database.ref('/Customer/Orders/{id}').onCreate((snap, context) => {

    //get the snapshot of the written data
    const snapShot = snap.val();
    console.log(snapShot);
    //create a notification
    const payload = {
        notification: {
            title: "New Order",
            body: "Please Check",
            badge: '1',
            sound: 'default',
        }
    };

    //send a notification to all fcmToken that are registered
    //In my case the users device token are stored in a node called 'fcmTokens'
    //and all user of my app will receive the notification
    return admin.database().ref('/Customer/fcmTokens').once('value').then(allToken => {
        const token = Object.keys(allToken.val());
        console.log(token);
            return admin.messaging().sendToDevice(token, payload)
    });
});

Console.log(token) looks like this { fcmToken: 'eRAAQEJAowI:APA91bHhZAa-kBhynq5b8_LkOhzYcp3v06H4IB5NgRp6k-2tZl67nF_eWuVHxL07KlzDVRfaINyoXBWDAJDFIFN23415NCHU-gZvK1LKw6Rwx8zz9S-' }

The error given is "Error: Registration token(s) provided to sendToDevice() must be a non-empty string or a non-empty array."

My Appledelegate.swift code - straight from Google's firebase github

import UIKit
import Firebase
import FirebaseMessaging
import FirebaseInstanceID
import UserNotifications

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

  var window: UIWindow?
  let gcmMessageIDKey = "gcm.message_id"

  func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    FirebaseApp.configure()
    Messaging.messaging().delegate = self
    Database.database().isPersistenceEnabled = true
    if #available(iOS 10.0, *) {
        // For iOS 10 display notification (sent via APNS)
        UNUserNotificationCenter.current().delegate = self

        let authOptions: UNAuthorizationOptions = [.alert, .badge, .sound]
        UNUserNotificationCenter.current().requestAuthorization(
            options: authOptions,
            completionHandler: {_, _ in })
    } else {
        let settings: UIUserNotificationSettings =
            UIUserNotificationSettings(types: [.alert, .badge, .sound], categories: nil)
        application.registerUserNotificationSettings(settings)
    }

    application.registerForRemoteNotifications()

    // [END register_for_notifications]
    return true
    }

    // [START receive_message]
    func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any]) {
        // If you are receiving a notification message while your app is in the background,
        // this callback will not be fired till the user taps on the notification launching the application.
        // TODO: Handle data of notification
        // With swizzling disabled you must let Messaging know about the message, for Analytics
        // Messaging.messaging().appDidReceiveMessage(userInfo)
        // Print message ID.
        if let messageID = userInfo[gcmMessageIDKey] {
            print("Message ID: \(messageID)")
        }

        // Print full message.
        print(userInfo)
    }

    func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any],
                     fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
        // If you are receiving a notification message while your app is in the background,
        // this callback will not be fired till the user taps on the notification launching the application.
        // TODO: Handle data of notification
        // With swizzling disabled you must let Messaging know about the message, for Analytics
        // Messaging.messaging().appDidReceiveMessage(userInfo)
        // Print message ID.
        if let messageID = userInfo[gcmMessageIDKey] {
            print("Message ID: \(messageID)")
        }

        // Print full message.
        print(userInfo)

        completionHandler(UIBackgroundFetchResult.newData)
    }
    // [END receive_message]
    func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {
        print("Unable to register for remote notifications: \(error.localizedDescription)")
    }

    // This function is added here only for debugging purposes, and can be removed if swizzling is enabled.
    // If swizzling is disabled then this function must be implemented so that the APNs token can be paired to
    // the FCM registration token.
    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        print("APNs token retrieved: \(deviceToken)")

        // With swizzling disabled you must set the APNs token here.
        // Messaging.messaging().apnsToken = deviceToken
    }
}

// [START ios_10_message_handling]
@available(iOS 10, *)
extension AppDelegate : UNUserNotificationCenterDelegate {

    // Receive displayed notifications for iOS 10 devices.
    func userNotificationCenter(_ center: UNUserNotificationCenter,
                                willPresent notification: UNNotification,
                                withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        let userInfo = notification.request.content.userInfo

        // With swizzling disabled you must let Messaging know about the message, for Analytics
        // Messaging.messaging().appDidReceiveMessage(userInfo)
        // Print message ID.
        if let messageID = userInfo[gcmMessageIDKey] {
            print("Message ID: \(messageID)")
        }

        // Print full message.
        print(userInfo)

        // Change this to your preferred presentation option
        completionHandler([])
    }

    func userNotificationCenter(_ center: UNUserNotificationCenter,
                                didReceive response: UNNotificationResponse,
                                withCompletionHandler completionHandler: @escaping () -> Void) {
        let userInfo = response.notification.request.content.userInfo
        // Print message ID.
        if let messageID = userInfo[gcmMessageIDKey] {
            print("Message ID: \(messageID)")
        }

        // Print full message.
        print(userInfo)

        completionHandler()
    }
}
// [END ios_10_message_handling]

extension AppDelegate : MessagingDelegate {
    // [START refresh_token]
    func messaging(_ messaging: Messaging, didReceiveRegistrationToken fcmToken: String) {
        print("Firebase registration token: \(fcmToken)")
        let ref = Database.database().reference().child("Customer").child("fcmTokens")
        ref.setValue(["fcmToken" : "\(fcmToken)"])
        let dataDict:[String: String] = ["token": fcmToken]
        NotificationCenter.default.post(name: Notification.Name("FCMToken"), object: nil, userInfo: dataDict)
        // TODO: If necessary send token to application server.
        // Note: This callback is fired at each app startup and whenever a new token is generated.
    }
    // [END refresh_token]
    // [START ios_10_data_message]
    // Receive data messages on iOS 10+ directly from FCM (bypassing APNs) when the app is in the foreground.
    // To enable direct data messages, you can set Messaging.messaging().shouldEstablishDirectChannel to true.
    func messaging(_ messaging: Messaging, didReceive remoteMessage: MessagingRemoteMessage) {
        print("Received data message: \(remoteMessage.appData)")
    }
    // [END ios_10_data_message]
}

Firebase: Registration token(s) provided to sendToDevice() must be a non-empty string or a non-empty array

Answers (1)

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