Recurring Notifications- OneSignal API Flutter

I am making a Calendar app where the user can schedule events.

The problem: User creates an event that repeats every week/day/month/year. I need to schedule a notification for every week/day/month/year at that date forever using the OneSignal API

What I've done

✅ Created normal scheduled notifications with POST requests and API

✅ Found a similar method using another plugin:

await flutterLocalNotificationsPlugin.showDailyAtTime(2, 'notification title', 'message here',
time, platformChannel,payload: 'new payload'));

I would need to translate this but using OneSignal.

What do I need?

• Find an option in OneSignal API to setup a recurring scheduled notification [Should be possible]
• In the case this is not possible, some logic or guidance as to how to schedule infinite possible notifications.

I have faced this issue, and I couldn't find any way to schedule notifications via OneSignal API.

What I did was I created an express API and added an endpoint to create a cron job to schedule the notification sending via one signal REST API.

Based on my own knowledge, there isn't a direct solution to schedule recurring notifications using OneSignal API but you can make something:

First, make sure you have all the dependencies:

import 'package:onesignal_flutter/onesignal_flutter.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';

Then use a function like this to schedule daily notifications (make sure to update APIs)

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

Future<void> scheduleDailyNotification(
    String title, String message, DateTime startTime) async {
  Map<String, dynamic> notification = {
    "app_id": "YOUR_APP_ID",
    "contents": {"en": message},
    "headings": {"en": title},
    "send_after": startTime.toUtc().toIso8601String(),
    "delayed_option": "daily",
    "delivery_time_of_day": startTime.toUtc().toIso8601String().substring(11, 19),
  };

  final headers = {
    'Content-Type': 'application/json',
    'Authorization': 'Basic YOUR_REST_API_KEY',
  };

  final response = await http.post(
    Uri.parse("https://onesignal.com/api/v1/notifications"),
    headers: headers,
    body: jsonEncode(notification),
  );
}

<!-- end snippet -->

Then call the function

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

scheduleDailyNotification(
  'Daily Notification Title',
  'Daily Notification Message',
  DateTime.now().add(Duration(minutes: 1)),
);

<!-- end snippet -->

This will schedule a daily notification starting one minute from the time of scheduling.

This solution can be suitable for daily recurring notifications and you may need to use a similar approach for weekly/monthly/yearly notifications by modifying the delayed_option and delivery_time_of_day values in the request.

For the scalability issue, I would create a backend service with an endpoint that creates a cron job to schedule the notification sending via OneSignal.