Getting customized message from GCM using Web push notifications

Question

I'm using Web push notifications with Chrome, and they work great. But now I want to deliver a custom message in my notifications. I can have my Service Worker call out to my site to get content, as is done at https://simple-push-demo.appspot.com/—which is fine if I want every recipient to see the same message.

Is there any way to get either the recipient’s registration_id or the message_id that GCM returns? If I could get either of these and include them in the callback to the service, I could customize the response.

Also, any info on when we might be able to include a payload in the call to GCM?

Answer 1

The registration_id and message_id fields aren't exposed, but if the user is previously authenticated to your app, any fetch() to the server from your Service Worker will include credentials (and session information) which you can use to identify them.

If that doesn't work for your case, you can store user/session information in IndexedDB.

Payloads are coming soon—likely Chrome 50 or 51—based on the Web Push protocol. It's a bit of extra overhead and work to configure the (required) encryption.

Answer 2

It's possible, but I wouldn't do it since it's specific to GCM, while other browsers use other services.

You can either create a unique ID for each user (like we're doing in Mercurius) and store it in IndexedDB, or you can use the entire endpoint URL as an ID.

Here's the snippet to get the registration_id:

self.registration.pushManager.getSubscription()
.then(function(subscription) {
  if (subscription) {
    var endpoint = subscription.endpoint;
    var endpointParts = endpoint.split('/');
    var gcmRegistrationID = endpointParts[endpointParts.length - 1];

    console.log(gcmRegistrationID);
  }
});

P.S.: It returns a promise, so make sure your service worker waits for the promise to be resolved.