Android FCM - how to show only one notification

Question

I\'m sending push notifications from FCM to an Android device, this is done by sending a POST message to FCM containing a JSON body.

If I send the same JSON body twi

Answer 1

Well, I kept digging and found the answer: it was not the "collapse_key", i was supposed to use the "tag" option in the notification instead.

So by using this JSON only one notification is shown:

{
    "notification": {
        "title": "MyAPP",
        "body": "Open MyAPP to access your data",
        "click_action" : "OPEN_MAINACTIVITY",
        "icon": "ic_launcher_red",
        "color": "#ff0000"
        "tag": "unique_tag"
    },
    "data": {
        "extra1":"sample1",
        "extra2":"sample2"
    },
    "registration_ids":[
        "--my_id--"
    ]
}

Hope this helps others!

And if someone wishes to explain further on "collapse_key" I would be glad, clearly I misunderstood it.