未初始化的常量 ActionCable

Question

我发现了与此类似的问题，但没有一个答案能解决问题。我有一个从 v4.2.5 升级到 5.1.5 的现有项目。我想使用Site Point tutorial 添加聊天室，但在使用 ActionCable 时遇到问题。每当我启动我的服务器时，它就会崩溃并出现以下错误：

/home/ubuntu/workspace/config/routes.rb:39:in `block in <top (required)>': uninitialized constant ActionCable (NameError)
        from /usr/local/rvm/gems/ruby-2.3.4/gems/actionpack-4.2.5/lib/action_dispatch/routing/route_set.rb:434:in `instance_exec'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/actionpack-4.2.5/lib/action_dispatch/routing/route_set.rb:434:in `eval_block'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/actionpack-4.2.5/lib/action_dispatch/routing/route_set.rb:412:in `draw'
        from /home/ubuntu/workspace/config/routes.rb:3:in `<top (required)>'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/application/routes_reloader.rb:40:in `block in load_paths'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/application/routes_reloader.rb:40:in `each'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/application/routes_reloader.rb:40:in `load_paths'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/application/routes_reloader.rb:16:in `reload!'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/application/routes_reloader.rb:26:in `block in updater'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/activesupport-4.2.5/lib/active_support/file_update_checker.rb:75:in `execute'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/application/routes_reloader.rb:27:in `updater'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/application/routes_reloader.rb:7:in `execute_if_updated'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/application/finisher.rb:69:in `block in <module:Finisher>'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/initializable.rb:30:in `instance_exec'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/initializable.rb:30:in `run'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/initializable.rb:55:in `block in run_initializers'
        from /usr/local/rvm/rubies/ruby-2.3.4/lib/ruby/2.3.0/tsort.rb:228:in `block in tsort_each'
        from /usr/local/rvm/rubies/ruby-2.3.4/lib/ruby/2.3.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
        from /usr/local/rvm/rubies/ruby-2.3.4/lib/ruby/2.3.0/tsort.rb:431:in `each_strongly_connected_component_from'
        from /usr/local/rvm/rubies/ruby-2.3.4/lib/ruby/2.3.0/tsort.rb:349:in `block in each_strongly_connected_component'
        from /usr/local/rvm/rubies/ruby-2.3.4/lib/ruby/2.3.0/tsort.rb:347:in `each'
        from /usr/local/rvm/rubies/ruby-2.3.4/lib/ruby/2.3.0/tsort.rb:347:in `call'
        from /usr/local/rvm/rubies/ruby-2.3.4/lib/ruby/2.3.0/tsort.rb:347:in `each_strongly_connected_component'
        from /usr/local/rvm/rubies/ruby-2.3.4/lib/ruby/2.3.0/tsort.rb:226:in `tsort_each'
        from /usr/local/rvm/rubies/ruby-2.3.4/lib/ruby/2.3.0/tsort.rb:205:in `tsort_each'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/initializable.rb:54:in `run_initializers'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/application.rb:352:in `initialize!'
        from /home/ubuntu/workspace/config/environment.rb:5:in `<top (required)>'
        from /home/ubuntu/workspace/config.ru:3:in `require'
        from /home/ubuntu/workspace/config.ru:3:in `block in <main>'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/rack-1.6.9/lib/rack/builder.rb:55:in `instance_eval'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/rack-1.6.9/lib/rack/builder.rb:55:in `initialize'
        from /home/ubuntu/workspace/config.ru:in `new'
        from /home/ubuntu/workspace/config.ru:in `<main>'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/rack-1.6.9/lib/rack/builder.rb:49:in `eval'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/rack-1.6.9/lib/rack/builder.rb:49:in `new_from_string'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/rack-1.6.9/lib/rack/builder.rb:40:in `parse_file'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/rack-1.6.9/lib/rack/server.rb:300:in `build_app_and_options_from_config'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/rack-1.6.9/lib/rack/server.rb:209:in `app'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/server.rb:61:in `app'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/rack-1.6.9/lib/rack/server.rb:337:in `wrapped_app'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/server.rb:139:in `log_to_stdout'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/server.rb:78:in `start'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:80:in `block in server'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:75:in `tap'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:75:in `server'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands.rb:17:in `<top (required)>'
        from bin/rails:4:in `require'
        from bin/rails:4:in `<main>'

我已经手动创建了以下文件来设置 ActionCable：

# app/channels/application_cable/channel.rb
module ApplicationCable
  class Channel < ActionCable::Channel::Base
  end
end

和

# 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
          logger.add_tags 'ActionCable', current_user.email
        end

        protected

        def find_verified_user # this checks whether a user is authenticated with devise
          if verified_user = env['warden'].user
            verified_user
          else
            reject_unauthorized_connection
          end
        end
  end
end

我尝试在我的 config/application.rb 顶部同时要求“action_cable”和“action_cable/engine”，但它给了我以下错误：

# including "require 'action_cable/engine' "
 /home/ubuntu/workspace/config/application.rb:4:in `require': cannot load such file -- action_cable/engine (LoadError)
        from /home/ubuntu/workspace/config/application.rb:4:in `<top (required)>'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:78:in `require'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:78:in `block in server'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:75:in `tap'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:75:in `server'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands.rb:17:in `<top (required)>'
        from bin/rails:4:in `require'
        from bin/rails:4:in `<main>'

和

# including "require 'action_cable' "
/home/ubuntu/workspace/config/application.rb:4:in `require': cannot load such file -- action_cable (LoadError)
        from /home/ubuntu/workspace/config/application.rb:4:in `<top (required)>'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:78:in `require'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:78:in `block in server'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:75:in `tap'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:75:in `server'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
        from /usr/local/rvm/gems/ruby-2.3.4/gems/railties-4.2.5/lib/rails/commands.rb:17:in `<top (required)>'
        from bin/rails:4:in `require'
        from bin/rails:4:in `<main>'

因为 Rails 5 是为了预加载 actioncable，所以我没有为它添加任何 gem。

我的 config/routes.rb 是：

include SessionsHelper

Rails.application.routes.draw do

  [...]
  mount ActionCable.server => '/cable'
  [...]
end

Answer 1

问题已解决 - 我不知道发生了什么，但应用程序未正确升级，并且在我尝试升级后未以 5.1.5 运行。我不得不再做一次，并从 config/application.rb 中删除以下行：config.active_record.raise_in_transactional_callbacks = true 以使其正常工作。