如何修复“无法从({”command“subscribe”，"identifier"=>"{\"channel\":\"ConversationChannel\"}"})“{”command“=>”subscribe“，

Question

我正在尝试让用户将用户连接到conversation_channel，我收到了：

Could not execute command from ({"command"=>"subscribe", "identifier"=>"  {\"channel\":\"ConversationChannel\"}"}) [NoMethodError - undefined method `id' for nil:NilClass]: /mnt/c/rails_apps/Picnotes/app/channels/conversation_channel.rb:6:in `subscribed' |

我尝试将current_user.id硬编码为1或2，得到：

Started GET "/cable" for 127.0.0.1 at 2019-01-22 22:06:36 -0800
Started GET "/cable/" [WebSocket] for 127.0.0.1 at 2019-01-22 22:06:36 -0800
Successfully upgraded to WebSocket (REQUEST_METHOD: GET, HTTP_CONNECTION: Upgrade, HTTP_UPGRADE: websocket)
ConversationChannel is transmitting the subscription confirmation
ConversationChannel is streaming from conversations-1

我的代码如下：

# Be sure to restart your server when you modify this file. Action Cable runs in a loop that does not support auto reloading.
class ConversationChannel < ApplicationCable::Channel
  # Create a unique channel for each user.
...
  def subscribed
    stream_from "conversations-#{current_user.id}"
  end

  # Removes all connected connections.
  def unsubscribed
    stop_all_streams
  end
...

  end
end    

module ApplicationCable
  class Connection < ActionCable::Connection::Base
    identified_by :current_user

    def connect
      self.current_user = current_user
    end
  end
end

class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception
  before_action :initiate_instance_variables

 ...

  def current_user
    @current_user ||= User.find_by(id: session[:user_id])
  end

  helper_method :current_user

  ...

end

我希望#{current_user.id}是用户id (常量:1或2)，但对象始终为空。

Answer 1

根据ActionCable的rails指南，您需要从cookie中获取用户id。

# 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 verified_user = User.find_by(id: cookies.encrypted[:user_id])
          verified_user
        else
          reject_unauthorized_connection
        end
      end
  end
end