未定義のメソッド `COLUMN_NAMES'

Question

rails generate active_admin:resource district

を実行して、私はactiveadminダッシュボードメニューでDistrictsメニューオプションを参照してくださいが、私はそれをクリックしたときに、私はこのエラー（URLはlocalhost：3000/adminに/地区）を取得

をここで

は、端末からの全体の出力である：ここでは

Started GET "/admin/districts" for ::1 at 2016-12-02 17:58:23 -0700 
Processing by Admin::DistrictsController#index as HTML 
    AdminUser Load (0.4ms) SELECT "admin_users".* FROM "admin_users" WHERE "admin_users"."id" = $1 ORDER BY "admin_users"."id" ASC LIMIT $2 [["id", 1], ["LIMIT", 1]] 
Completed 500 Internal Server Error in 8ms (ActiveRecord: 0.4ms) 



NoMethodError (undefined method `column_names' for District:Module): 

/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/activeadmin-a932d56b156e/lib/active_admin/resource.rb:101:in `resource_column_names' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/activeadmin-a932d56b156e/lib/active_admin/order_clause.rb:19:in `to_sql' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/activeadmin-a932d56b156e/lib/active_admin/resource_controller/data_access.rb:216:in `apply_sorting' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/activeadmin-a932d56b156e/lib/active_admin/resource_controller/data_access.rb:58:in `block in find_collection' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/activeadmin-a932d56b156e/lib/active_admin/resource_controller/data_access.rb:57:in `each' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/activeadmin-a932d56b156e/lib/active_admin/resource_controller/data_access.rb:57:in `find_collection' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/activeadmin-a932d56b156e/lib/active_admin/resource_controller/data_access.rb:42:in `collection' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/inherited_resources-4434f0ae72f7/lib/inherited_resources/actions.rb:7:in `index' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/activeadmin-a932d56b156e/lib/active_admin/resource_controller/streaming.rb:12:in `index' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_controller/metal/basic_implicit_render.rb:4:in `send_action' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/abstract_controller/base.rb:188:in `process_action' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_controller/metal/rendering.rb:30:in `process_action' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/abstract_controller/callbacks.rb:20:in `block in process_action' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/activesupport/lib/active_support/callbacks.rb:132:in `run_callbacks' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/abstract_controller/callbacks.rb:19:in `process_action' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_controller/metal/rescue.rb:20:in `process_action' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_controller/metal/instrumentation.rb:32:in `block in process_action' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/activesupport/lib/active_support/notifications.rb:164:in `block in instrument' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/activesupport/lib/active_support/notifications/instrumenter.rb:21:in `instrument' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/activesupport/lib/active_support/notifications.rb:164:in `instrument' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_controller/metal/instrumentation.rb:30:in `process_action' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_controller/metal/params_wrapper.rb:248:in `process_action' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/activerecord/lib/active_record/railties/controller_runtime.rb:18:in `process_action' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/abstract_controller/base.rb:126:in `process' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionview/lib/action_view/rendering.rb:30:in `process' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_controller/metal.rb:194:in `dispatch' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_controller/metal.rb:266:in `dispatch' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/routing/route_set.rb:49:in `dispatch' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/routing/route_set.rb:31:in `serve' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/journey/router.rb:39:in `block in serve' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/journey/router.rb:26:in `each' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/journey/router.rb:26:in `serve' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/routing/route_set.rb:725:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/middleware/cookies.rb:613:in `call' 
rack (2.0.1) lib/rack/method_override.rb:22:in `call' 
warden (1.2.6) lib/warden/manager.rb:35:in `block in call' 
warden (1.2.6) lib/warden/manager.rb:34:in `catch' 
warden (1.2.6) lib/warden/manager.rb:34:in `call' 
rack (2.0.1) lib/rack/etag.rb:25:in `call' 
rack (2.0.1) lib/rack/conditional_get.rb:25:in `call' 
rack (2.0.1) lib/rack/head.rb:12:in `call' 
rack (2.0.1) lib/rack/session/abstract/id.rb:222:in `context' 
rack (2.0.1) lib/rack/session/abstract/id.rb:216:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/middleware/cookies.rb:613:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/activerecord/lib/active_record/migration.rb:555:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/middleware/callbacks.rb:38:in `block in call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/activesupport/lib/active_support/callbacks.rb:104:in `run_callbacks' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/middleware/callbacks.rb:36:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/middleware/executor.rb:12:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/middleware/remote_ip.rb:79:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb:59:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/middleware/show_exceptions.rb:31:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/railties/lib/rails/rack/logger.rb:36:in `call_app' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/railties/lib/rails/rack/logger.rb:24:in `block in call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/activesupport/lib/active_support/tagged_logging.rb:69:in `block in tagged' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/activesupport/lib/active_support/tagged_logging.rb:26:in `tagged' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/activesupport/lib/active_support/tagged_logging.rb:69:in `tagged' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/railties/lib/rails/rack/logger.rb:24:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/middleware/request_id.rb:25:in `call' 
rack (2.0.1) lib/rack/method_override.rb:22:in `call' 
rack (2.0.1) lib/rack/runtime.rb:22:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/activesupport/lib/active_support/cache/strategy/local_cache_middleware.rb:27:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/middleware/executor.rb:12:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/actionpack/lib/action_dispatch/middleware/static.rb:125:in `call' 
rack (2.0.1) lib/rack/sendfile.rb:111:in `call' 
/Users/username/.rvm/gems/ruby-2.3.0/bundler/gems/rails-45f8848ca7d7/railties/lib/rails/engine.rb:522:in `call' 
puma (3.6.2) lib/puma/configuration.rb:225:in `call' 
puma (3.6.2) lib/puma/server.rb:578:in `handle_request' 
puma (3.6.2) lib/puma/server.rb:415:in `process_client' 
puma (3.6.2) lib/puma/server.rb:275:in `block in run' 
puma (3.6.2) lib/puma/thread_pool.rb:116:in `block in spawn_thread' 

は、いくつかの追加情報

モデル/ district.rb

module District 
    def self.table_name_prefix 
    'district_' 
    end 
end 

アプリ/管理/地区です.rb

私は問題が何であるかを見つけることができないよう5.1.0.alpha

ActiveAdmin.register District do 
    index do 
     selectable_column 
     id_column 
     column :name 
     column :created_at 
     actions 
     end 
end 

Rubyのバージョン ルビー2.3.0p0

Railsのバージョン Railsの。どんな助けもありがとう！

Answer 1

NoMethodError（未定義のメソッド `District_ Moduleの` column_names '）エラーは、あなたの地区モジュール定義から来ています。これは、代わりにモジュールのクラスであるとの理由でモデルをActiveRecordは::ベースから継承されたメソッドCLASS_NAMEを持っているということであるレール4

class District < ActiveRecord::Base 
    def self.table_name_prefix 
    'district_' 
    end 
end 

ためのActiveRecord ::ベースを継承しなければなりません。 Rails 5では、モデルクラスはApplicationRecordを継承する必要があります。