Flutterfire: [firebase_messaging] Localization of notifications does not work

[bscottsmith]

The FCM fields used for localizing (I18N) the notification title and body are not working.
For example:

{
  "android" : {
    "priority" : "normal",
    "notification" : {
      "title_loc_key": "notify_title",
      "body_loc_key": "notify_body"
    }
  }
}

The FCM documentation states that these fields are used to localize the text in the "app's string resources", but Flutter does not have a res/values/strings.xml file.
I am using the flutter_localizations library, and maintain res/values/strings_<lang>.arb files as required by Flutter for internationalization, but there is no way for me to tell firebase_messaging to use these resources.

[TahaTesser]

hI @bscottsmith
This platform is not meant for assistance on personal code.
Please see https://flutter.dev/community for resources and asking questions like this, you may also get some help if you post it on Stack Overflow.
Closing, as this isn't an issue with Flutter itself,
if you disagree please write in the comments and I will reopen it
Thank you

[bscottsmith]

I don't understand. How is the fact that firebase_messaging doesn't support localization of FCM notifications an issue with "personal code"? Are you saying that the title_loc_key and body_loc_key FCM fields are, in fact, supported by firebase_messaging, and therefore I may have a coding issue on my end?

[bscottsmith]

@TahaTesser, I see that you assigned a type of "documentation" to this issue.
Are you saying that the title_loc_key and body_loc_key FCM fields are, in fact, supported by firebase_messaging, and that it is simply not documented correctly?
I would appreciate your input on this, as I can not find any way to support localization of the FCM notifications with the firebase_messaging plugin.

[TahaTesser]

Hi @bscottsmith
I assigned documentation label so we can have examples of localized notifications

[vinnytwice]

@bscottsmith Hi, did you manage to have messages localized? I'm hitting the same wall here.
https://github.com/FirebaseExtended/flutterfire/issues/2759

[bscottsmith]

@vinnytwice: Nope. And unfortunately, it still isn't even assigned. @TahaTesser assigned this issue a type "documentation", which implies localization is supported and simply needs to be documented, so I worry this will never be assigned to a developer, even though I don't believe this plugin supports it at all (how do you document something that isn't supported?)...

[vinnytwice]

@bscottsmith I see that @TahaTesser hasn't really answered that localization is supported, but it's fair to assume that.
This is how I sent the notification, do you do anything different?

void sendBookingReceived(Booking booking) async {
    print('sendBookingReceived() started');
    var customerName = booking.customerName;
    var bookingStart = booking.bookingStart;
    var customerFCMToken = booking.customerFCMToken;

    await post('https://fcm.googleapis.com/fcm/send',
        headers: <String, String>{
          'Content-Type': 'application/json',
          'Authorization': 'key=$firebaseServerKey'
        },
        body: jsonEncode({
          'notification': <String, dynamic>{
            'title_loc_key': 'BOOKING_RECEIVED_PUSH_SUBTITLE',
            'title_loc_args': [booking.shopName],
            'body_loc_key': 'BOOKING_RECEIVED_PUSH_BODY',
            'body_loc_args': [
              customerName,
              '',
              bookingStart
            ], //, bookingDate, bookingStart]),
            'sound': 'true',
            'mutable_content': 'true',
            'content_available': 'true'
},
          'priority': 'high',
          'data': <String, dynamic>{
            'click_action': 'FLUTTER_NOTIFICATION_CLICK',
            'id': '1',
            'status': 'done'
          },
          'to': customerFCMToken
        })).whenComplete(() {
      print('sendBookingReceived(): message sent');
    }).catchError((e) {
      print('sendBookingReceived() error: $e');
    });
  }

Also I had a look at the plugin code but I couldn't really see if it supports localization.
So @TahaTesser I know that you guys are pretty busy but can you please make clear if it's supported or not?
Really appreciate all the efforts.

Cheers

[TahaTesser]

@bscottsmith
It's fair to say there is no documentation for this, i couldn't find any but attempting to try it has some issues so i am assigning bug label too

[vinnytwice]

@TahaTesser nice one, hope it gets fixed soon. Thanks for the clarification on the subject.

[mo-ah-dawood]

yes i hope to found this feature working soon
and it has to be localized according to Localizations.localeOf(context) => material app locale

[crtl]

I havent found any documentation for these fields but they are present in the firebase sdks.
The following code is taken from the firebase admin nodejs sdk:

 // admin.messaging.NotificationMessagePayload

  /**
   * Interface representing an FCM legacy API notification message payload.
   * Notification messages let developers send up to 4KB of predefined
   * key-value pairs. Accepted keys are outlined below.
   *
   * See [Build send requests](/docs/cloud-messaging/send-message)
   * for code samples and detailed documentation.
   */
  interface NotificationMessagePayload {

    /**
     * Identifier used to replace existing notifications in the notification drawer.
     *
     * If not specified, each request creates a new notification.
     *
     * If specified and a notification with the same tag is already being shown,
     * the new notification replaces the existing one in the notification drawer.
     *
     * **Platforms:** Android
     */
    tag?: string;

    /**
     * The notification's body text.
     *
     * **Platforms:** iOS, Android, Web
     */
    body?: string;

    /**
     * The notification's icon.
     *
     * **Android:** Sets the notification icon to `myicon` for drawable resource
     * `myicon`. If you don't send this key in the request, FCM displays the
     * launcher icon specified in your app manifest.
     *
     * **Web:** The URL to use for the notification's icon.
     *
     * **Platforms:** Android, Web
     */
    icon?: string;

    /**
     * The value of the badge on the home screen app icon.
     *
     * If not specified, the badge is not changed.
     *
     * If set to `0`, the badge is removed.
     *
     * **Platforms:** iOS
     */
    badge?: string;

    /**
     * The notification icon's color, expressed in `#rrggbb` format.
     *
     * **Platforms:** Android
     */
    color?: string;

    /**
     * The sound to be played when the device receives a notification. Supports
     * "default" for the default notification sound of the device or the filename of a 
     * sound resource bundled in the app. 
     * Sound files must reside in `/res/raw/`.
     * 
     * **Platforms:** Android
     */
    sound?: string;

    /**
     * The notification's title.
     *
     * **Platforms:** iOS, Android, Web
     */
    title?: string;

    /**
     * The key to the body string in the app's string resources to use to localize
     * the body text to the user's current localization.
     *
     * **iOS:** Corresponds to `loc-key` in the APNs payload. See
     * [Payload Key Reference](https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/PayloadKeyReference.html)
     * and
     * [Localizing the Content of Your Remote Notifications](https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/CreatingtheNotificationPayload.html#//apple_ref/doc/uid/TP40008194-CH10-SW9)
     * for more information.
     *
     * **Android:** See
     * [String Resources](http://developer.android.com/guide/topics/resources/string-resource.html)      * for more information.
     *
     * **Platforms:** iOS, Android
     */
    bodyLocKey?: string;

    /**
     * Variable string values to be used in place of the format specifiers in
     * `body_loc_key` to use to localize the body text to the user's current
     * localization.
     *
     * The value should be a stringified JSON array.
     *
     * **iOS:** Corresponds to `loc-args` in the APNs payload. See
     * [Payload Key Reference](https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/PayloadKeyReference.html)
     * and
     * [Localizing the Content of Your Remote Notifications](https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/CreatingtheNotificationPayload.html#//apple_ref/doc/uid/TP40008194-CH10-SW9)
     * for more information.
     *
     * **Android:** See
     * [Formatting and Styling](http://developer.android.com/guide/topics/resources/string-resource.html#FormattingAndStyling)
     * for more information.
     *
     * **Platforms:** iOS, Android
     */
    bodyLocArgs?: string;

    /**
     * Action associated with a user click on the notification. If specified, an
     * activity with a matching Intent Filter is launched when a user clicks on the
     * notification.
     *
     *   * **Platforms:** Android
     */
    clickAction?: string;

    /**
     * The key to the title string in the app's string resources to use to localize
     * the title text to the user's current localization.
     *
     * **iOS:** Corresponds to `title-loc-key` in the APNs payload. See
     * [Payload Key Reference](https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/PayloadKeyReference.html)
     * and
     * [Localizing the Content of Your Remote Notifications](https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/CreatingtheNotificationPayload.html#//apple_ref/doc/uid/TP40008194-CH10-SW9)
     * for more information.
     *
     * **Android:** See
     * [String Resources](http://developer.android.com/guide/topics/resources/string-resource.html)
     * for more information.
     *
     * **Platforms:** iOS, Android
     */
    titleLocKey?: string;

    /**
     * Variable string values to be used in place of the format specifiers in
     * `title_loc_key` to use to localize the title text to the user's current
     * localization.
     *
     * The value should be a stringified JSON array.
     *
     * **iOS:** Corresponds to `title-loc-args` in the APNs payload. See
     * [Payload Key Reference](https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/PayloadKeyReference.html)
     * and
     * [Localizing the Content of Your Remote Notifications](https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/CreatingtheNotificationPayload.html#//apple_ref/doc/uid/TP40008194-CH10-SW9)
     * for more information.
     *
     * **Android:** See
     * [Formatting and Styling](http://developer.android.com/guide/topics/resources/string-resource.html#FormattingAndStyling)
     * for more information.
     *
     * **Platforms:** iOS, Android
     */
    titleLocArgs?: string;
    [key: string]: string | undefined;
  }

[mo-ah-dawood]

any update here

[Dn-a]

I'm waiting for it too

[pumuckelo]

This would be awesome if we can find a solution for this!

[pumuckelo]

Meanwhile, for a quick & dirty solution you could save the locale of the device (Platform.localeName) to the device token in your database and then send the correct message in your cloud function depending on the locale of the token.

[spiderion]

As a workaround for android:
we can create a file under the path: ../android/app/src/main/res/values/strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="your_string_key">Your string</string>
</resources>

define all the default strings there
and create separate files for localized countries (as usually native android works)