Firebase cloud messaging duplicate notifications

Question

We are using Firebase cloud messaging. Sometimes when Android or iOS app is in sleep mode the cell phone receives same (duplicates) notifications messages. For device identifications the FIRInstanceID token is used. An external server on node.js is used for sending notifications to Firebase service. No duplications in our server log file are presented.

Answer 1

in file firebase-messaging-sw.js

comment this line

// self.registration.showNotification(notificationTitle,notificationOptions)

and no duplicate fcm anymore

Answer 2

If you are working with Firebase-sw.js then here is what is happening.

"Note this is not for admin SDK"

When you send "notification" key in the payload it triggers the default behaviour of the of the browser and it shows the notification. Then in your service provider you are showing the notification again:

self.registration.showNotification(notificationTitle,notificationOptions)

...You are not at fault because the firebase documentation did not mention any details about it.

Solution You have to remove the "notification" key from your payload and modify your firebase-sw.js file like this:

messaging.onBackgroundMessage(function(payload) {
  console.log('Received background message ', payload);

  const notificationTitle = payload.data.title;
  const notificationOptions = {
    body: payload.data.body
  };
  self.registration.showNotification(notificationTitle, notificationOptions);
});

and your payload should look like this:

{
    "data": {
        "title":"New Ride Request",
        "body":"A new ride has been requested",
        "sound" : "default"
    },
    "condition": "'topic1' in topics"
}  

Now your default notification will not trigger and your code level notification will be displayed only.