Get GCM canonical registration ID without sending a message

Question

I have a problem with an app using GCM, the scenario is this:

1. the app is installed
2. the app calls the GCM register method getting the registration id \"RID

Answer 1

You can specify "dry_run": true option in /send request.

I found that devices do not receive any push notifications with "dry_run": true option, while a server get canonical_ids response.

Here is a sample code in Ruby. You may have to install gcm Gem beforehand.

$ gem install gcm

ask_canonical_ids.rb

require 'gcm'
require 'json'

API_KEY = "YourApiKey"
gcm = GCM.new(API_KEY)

registration_ids = [
  'OldRegistrationId',
]

option = { data: { 'message' => 'Hello Gcm!' }, dry_run: true }
response = gcm.send_notification(registration_ids, option)

p response[:canonical_ids]

output of $ ruby ask_canonical_ids.rb (formatted)

[{
  :old => "OldRegistrationId",
  :new => "NewRegistrationId"
}]

Again, your device will not receive any push notifications.