[question]: NotificationServiceExtension: How to notify Ionic application when recieve background/data/silent notification?

[anatoly-spb]

How can we help?

I want to receive background/data/silent notification in my Ionic Application based on onesignal-cordova-plugin@5.1.4 and Capacitor:

import { Component } from '@angular/core';
import { IonApp, IonRouterOutlet } from '@ionic/angular/standalone';
import OneSignal from 'onesignal-cordova-plugin';

@Component({
  selector: 'app-root',
  templateUrl: 'app.component.html',
  standalone: true,
  imports: [IonApp, IonRouterOutlet],
})
export class AppComponent {
  constructor() {
    OneSignal.Debug.setLogLevel(6)
    OneSignal.initialize("xxxx")
    OneSignal.Notifications.addEventListener('click', async (e) => {
      let clickData = await e.notification;
      console.log("Notification Clicked : "  + JSON.stringify(clickData));
    })
    OneSignal.Notifications.addEventListener('foregroundWillDisplay', async (e) => {
      let notification = await e.getNotification();
      console.log("Notification Foreground Will Displayed : "  + JSON.stringify(notification));
    })
    OneSignal.Notifications.addEventListener('permissionChange', async (e) => {
      let success = await e;
      console.log("Notification Permission Changed : "  + success);
    })
    OneSignal.Notifications.requestPermission(true).then((success: Boolean) => {
      console.log("Notification permission granted " + success);
    })
    OneSignal.User.pushSubscription.getIdAsync().then(id=>{
      console.log("Notification Subscription ID: " + id);
    })
    // XXXXXXXXXX
  }
}

. According to documentation https://documentation.onesignal.com/docs/data-notifications I have implemented NotificationServiceExtension for Android:

import androidx.annotation.Keep;
import androidx.annotation.NonNull;

import com.onesignal.debug.internal.logging.Logging;
import com.onesignal.notifications.IDisplayableMutableNotification;
import com.onesignal.notifications.INotificationReceivedEvent;
import com.onesignal.notifications.INotificationServiceExtension;
@Keep
public class NotificationServiceExtension implements INotificationServiceExtension {
  @Override
  public void onNotificationReceived(@NonNull INotificationReceivedEvent event) {
    IDisplayableMutableNotification notification = event.getNotification();

    Logging.info(String.format("NotificationServiceExtension::onNotificationReceived: notificationId=%s, rawPayload=%s", notification.getNotificationId(), notification.getRawPayload()), null);
    // YYYYYYYYYYY
  }
}

But what should I call inside onNotificationReceived instead of YYYYYYYYYYY to pass this notification to Ionic Application based on Capacitor and what should I write instead of XXXXXXXXXX to subscribe on background/data/silent notification?

Thanks in advance,
Anatoly Shirokov

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[jkasten2]

@anatoly-spb

Keep in mind that background/silent are not always the best fit, so it is recommend you provide more details on your goal to see if there are better options.

We don't have a specific guide on doing bridging like this but you could use some like Ionic App Events if you need get some information from Java / Kotlin native to JavaScript.
https://capacitorjs.com/docs/v2/plugins/android#app-events

[chijete]

There is no direct implementation of this plugin to receive silent notifications from OneSignal, but I have made an implementation that allows you to receive an event when a silent notification is received, even when the app is closed (Java side).

Step 1: Add a function in MainActivity to use the Bridge

This will allow us to send Java events to Javascript.

Edit file MainActivity.java (your-proyect/android/app/src/main/java/com/your/package/MainActivity.java)

package com.your.package; // Replace with your package name

import com.getcapacitor.BridgeActivity;

// Imports:
import android.util.Log;
import android.os.Bundle;

public class MainActivity extends BridgeActivity {
    private static MainActivity instance;
    private static final String TAG = "MainActivity";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        instance = this;
    }

    public static MainActivity getInstance() {
        return instance;
    }

    public void handleNotificationPayload(String payload) {
        Log.d(TAG, "Payload received: " + payload);
        bridge.triggerJSEvent("onCapacitorOneSignalNotificationReceived", "window", payload);
    }
}

Step 2: Intercept notifications coming from OneSignal.

Create file NotificationServiceExtension.java at your-proyect/android/app/src/main/java/com/your/package/

package com.your.package; // Replace with your package name

import com.onesignal.notifications.IActionButton;
import com.onesignal.notifications.IDisplayableMutableNotification;
import com.onesignal.notifications.INotificationReceivedEvent;
import com.onesignal.notifications.INotificationServiceExtension;

import android.os.Handler;
import android.util.Log;

import org.json.JSONObject;
import java.util.HashMap;

import com.getcapacitor.JSObject;

import androidx.annotation.Keep; // To prevent the minifier from removing this class

@Keep
public class NotificationServiceExtension implements INotificationServiceExtension {
    private static final String TAG = "NotificationServiceExtension";

    @Override
    public void onNotificationReceived(INotificationReceivedEvent event) {
        IDisplayableMutableNotification notification = event.getNotification();

        String rawPayloadStr = notification.getRawPayload();

        Log.d(TAG, "rawPayloadStr: " + rawPayloadStr); // Optional: Log the raw payload in logcat.

        try {

            MainActivity mainActivity = MainActivity.getInstance();
            if (mainActivity != null) {
                mainActivity.handleNotificationPayload(rawPayloadStr);
            } else {
                Log.e(TAG, "MainActivity instance is null");
            }
            
        } catch (Exception e) {
            Log.e(TAG, "MainActivity send error: " + e.getMessage());
        }
    }
}

Advanced:

All notifications received from OneSignal are intercepted in this file.

Here you could do something else with the notification data, even when the app is closed.

Step 3: Add the NotificationServiceExtension to the AndroidManifest

Edit file AndroidManifest.xml (your-proyect/android/app/src/main/AndroidManifest.xml)

Add this:

<meta-data
            android:name="com.onesignal.NotificationServiceExtension"
            android:value="com.your.package.NotificationServiceExtension"
        />

Inside of <application> tag.

(Replace com.your.package with your package name).

Step 4: Receive the event with Javascript

With this code you can listen to the event from Javascript when the application is active.

window.addEventListener('onCapacitorOneSignalNotificationReceived', (event) => {
  console.log('Notification received with payload:', event);
});

How to send a silent notification

With OneSignal API:

curl --request POST \
     --url 'https://api.onesignal.com/notifications?c=push'
--data '
{
  "app_id": "XXX-XXX-XXX",
  "include_subscription_ids": ["YYY-YYY-YYY"],
  "target_channel": "push",
  "content_available": true,
  "data": {
    "info": { "key": "value" }
  }
}

See https://documentation.onesignal.com/reference/push-notification

Footnote:

• This code does not disable the plugin from receiving notifications. The plugin will still receive visible notifications and display them in the notification bar.
• This code is designed for Android only.
• "Silent notifications" are those sent with content_available = true

Documentation and reference:

• https://documentation.onesignal.com/docs/service-extensions
• https://documentation.onesignal.com/docs/osnotification-payload
• https://documentation.onesignal.com/docs/data-notifications