How do I get current_user in ActionCable rails-5-api app?

Question

Why am I not able to retrieve current_user inside my channel or how should I retrieve current_user?

What do I use?

• Rails 5.0.1 --api (I do NOT have any views NOR use coffee)
• I use react-native app to test this (Works fine WITHOUT authorization)
• I do NOT use devise for auth (I use JWT instead using Knock, so no cookies)

Trying to get current_user inside my ActionCable channel as described in rubydoc.info

The code looks like

class MessageChannel < ApplicationCable::Channel
  identified_by :current_user

  def subscribed
    stream_from 'message_' + find_current_user_privileges
  end

  def unsubscribed
    # Any cleanup needed when channel is unsubscribed
  end

  protected

  def find_current_user_privileges
    if current_user.has_role? :admin
      'admin'
    else
      'user_' + current_user.id
    end
  end

end

And running it, I get this error:

[NoMethodError - undefined method `identified_by' for MessageChannel:Class]

And if I remove identified_by :current_user, I get

[NameError - undefined local variable or method `current_user' for #<MessageChannel:0x7ace398>]

Answer 1

If you see the doc you provided, you will know that identified_by is not a method for a Channel instance. It is a method for Actioncable::Connection. From Rails guide for Actioncable Overview, this is how a Connection class looks like:

#app/channels/application_cable/connection.rb
module ApplicationCable
  class Connection < ActionCable::Connection::Base
    identified_by :current_user

    def connect
      self.current_user = find_verified_user
    end

    private
      def find_verified_user
        if current_user = User.find_by(id: cookies.signed[:user_id])
          current_user
        else
          reject_unauthorized_connection
        end
      end
  end
end

As you can see, current_user is not available here. Instead, you have to create a current_user here in connection.

The websocket server doesn't have a session, but it can read the same cookies as the main app. So I guess, you need to save cookie after authentication.