ActionView::Template::Error (undefined method `tr' for nil:NilClass - ruby-on-rails

Question

I am testing out the service-worker rails gem and am using VAPID private and public keys to send push notifications. I've succesfully been able to create push notifications locally, but when I deploy to heroku, the app raises the error stated above when trying to go to the push notification page. Here is the error:
75] Started GET "/push-simple/" for 69.253.120.203 at 2017-02-12 06:37:35 +0000
2017-02-12T06:37:35.339318+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] ActionView::Template::Error (undefined method `tr' for nil:NilClass
2017-02-12T06:37:35.333379+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] Rendering pages/push-simple.html.erb within layouts/application
2017-02-12T06:37:35.332337+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] Processing by PagesController#show as HTML
2017-02-12T06:37:35.336377+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] Rendered pages/push-simple.html.erb within layouts/application (2.8ms)
2017-02-12T06:37:35.336998+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] Completed 500 Internal Server Error in 4ms
2017-02-12T06:37:35.339281+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75]
2017-02-12T06:37:35.339490+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] 13: <script type="text/javascript">
2017-02-12T06:37:35.339320+00:00 app[web.1]: Did you mean? try):
2017-02-12T06:37:35.339489+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] 11: </div>
2017-02-12T06:37:35.339489+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] 12:
2017-02-12T06:37:35.339561+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] app/views/pages/push-simple.html.erb:14:in `_app_views_pages_push_simple_html_erb__2838769268823495646_39526220'
2017-02-12T06:37:35.339491+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] 15: </script>
2017-02-12T06:37:35.339491+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] 14: var publicKey = new Uint8Array(<%= WebpushClient.public_key_bytes %>);
2017-02-12T06:37:35.339492+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] 16: <%= javascript_include_tag 'push-simple' %>
2017-02-12T06:37:35.339520+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75]
2017-02-12T06:37:35.339560+00:00 app[web.1]: [3d626b62-4c1b-41ca-aad3-fc653dc96b75] app/clients/webpush_client.rb:7:in `public_key_bytes'
And here is my webpushclient where the VAPID keys are defined:
class WebpushClient
def self.public_key
ENV['VAPID_PUBLIC_KEY']
end
def self.public_key_bytes
Base64.urlsafe_decode64(public_key).bytes
end
def self.private_key
ENV['VAPID_PRIVATE_KEY']
end
# Send webpush message using subscription parameters
#
# #param message [String] text to encrypt
# #param subscription_params [Hash<Symbol, String>]
# #option subscription_params [String] :endpoint url to send encrypted message
# #option subscription_params [Hash<Symbol, String>] :keys auth keys to send with message for decryption
# #return true/false
def send_notification(message, endpoint: "", p256dh: "", auth: "")
raise ArgumentError, ":endpoint param is required" if endpoint.blank?
raise ArgumentError, "subscription :keys are missing" if p256dh.blank? || auth.blank?
Rails.logger.info("Sending WebPush notification...............")
Rails.logger.info("message: #{message}")
Rails.logger.info("endpoint: #{endpoint}")
Rails.logger.info("p256dh: #{p256dh}")
Rails.logger.info("auth: #{auth}")
Webpush.payload_send \
message: message,
endpoint: endpoint,
p256dh: p256dh,
auth: auth,
vapid: {
subject: "jon.corrin#gmail.com",
public_key: public_key,
private_key: private_key
}
end
def public_key
self.class.public_key
end
def private_key
self.class.private_key
end
end
and here is the script im using to call the public key:
<script type="text/javascript">
var publicKey = new Uint8Array(<%= WebpushClient.public_key_bytes %>);
</script>
<%= javascript_include_tag 'push-react' %>
Like I said before, it works locally. I think I may have forgotten to define a variable, I've looked at similar posts and have been debugging for quite some time, but have had no luck. Any suggestions? I also want to add, I'm quite new, so if it's an obvious error, I'll completely understand.

Answer 1

Your error is coming from this method:
def self.public_key_bytes
Base64.urlsafe_decode64(public_key).bytes
end
Looking up the source code for Base64#urlsafe_decode64, this is defined by:
def urlsafe_decode64(str)
strict_decode64(str.tr("-_", "+/"))
end
This is where your undefined method 'tr' for nil:NilClass must be coming from: the public_key. Which you have defined by:
def self.public_key
ENV['VAPID_PUBLIC_KEY']
end
...In other words, you have not set the environmental variable on your production server. That's why it works locally, but not on production.