Жемчужина квартиры выдает непредвиденную ошибку при создании модели на Rails 5.1.0

Я новичок в рельсовой платформе. Я создаю мультитенантное приложение с помощью Apartment gem. Я подписываюсь на https://medium.com/@balogic/using-apartment-gem-to-implement-multitenant-concept-in-rails-b86f7d9e37c5 это руководство, чтобы узнать, как использовать этот драгоценный камень. Но когда я создаю леса или создаю модель пользователя, я получаю следующую ошибку:

$ rails g scaffold Users email name subdomain C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.1.0/lib/action _dispatch/middleware/stack.rb:35:in `build': undefined method `new' for "Apartme nt::Elevators::Subdomain":String (NoMethodError) Did you mean? next from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.1 .0/lib/action_dispatch/middleware/stack.rb:99:in `block in build' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.1 .0/lib/action_dispatch/middleware/stack.rb:99:in `each' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.1 .0/lib/action_dispatch/middleware/stack.rb:99:in `inject' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.1 .0/lib/action_dispatch/middleware/stack.rb:99:in `build' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/engine.rb:508:in `block in app' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/engine.rb:504:in `synchronize' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/engine.rb:504:in `app' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/application/finisher.rb:45:in `block in <module:Finisher>' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/initializable.rb:30:in `instance_exec' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/initializable.rb:30:in `run' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/initializable.rb:59:in `block in run_initializers' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/2.3.0/tsort.rb:228:in `block i n tsort_each' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/2.3.0/tsort.rb:350:in `block ( 2 levels) in each_strongly_connected_component' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/2.3.0/tsort.rb:431:in `each_st rongly_connected_component_from' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/2.3.0/tsort.rb:349:in `block i n each_strongly_connected_component' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `each' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `call' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `each_st rongly_connected_component' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/2.3.0/tsort.rb:226:in `tsort_e ach' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/2.3.0/tsort.rb:205:in `tsort_e ach' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/initializable.rb:58:in `run_initializers' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/application.rb:353:in `initialize!' from C:/Sites/multitenant_app/config/environment.rb:5:in `<top (required )>' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/application.rb:329:in `require' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/application.rb:329:in `require_environment!' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/command/actions.rb:16:in `require_application_and_environment!' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/commands/generate/generate_command.rb:19:in `perform' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/thor-0.19.4/li b/thor/command.rb:27:in `run' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/thor-0.19.4/li b/thor/invocation.rb:126:in `invoke_command' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/thor-0.19.4/li b/thor.rb:369:in `dispatch' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/command/base.rb:63:in `perform' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/command.rb:44:in `invoke' from C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/railties-5.1.0 /lib/rails/commands.rb:16:in `<top (required)>' from bin/rails:4:in `require' from bin/rails:4:in `<main>'

** Примечание. ** Моя версия Rails - 5.0.1, а версия Ruby - 2.3.0.