TypeError: wrong argument type Class (expected Mod

Question

So I have this controller named guests_controller.rb which looks like this:

class GuestsController < ApplicationController
    include Data

    def index
        display_data("db")
        display_data("session")
    end

    def new
        @guest = Guest.new
    end

    def create
        case params[:option]
            when '0'
                logger.debug 'Salvestame andmebaasi'
                save_data("db")
            when '1'
                logger.debug 'Salvestame sessiooni'
                save_data("session")
        end
    end

    private
    def guest_params
        params.require(:guest).permit(:name, :text)
    end
end

And also I have a concern named data.rb in controllers/concens/:

module Data
    extend ActiveSupport:Concern

    def save_data(save_method)
        case save_method
            when "db"
                @guest = Guest.new(guest_params)
                if @guest.save
                    flash[:success] = "New guest entry created!"
                    redirect_to guests_path
                else
                    render 'new'
                end
            when "session"
                name = params[:guest][:name].to_s
                text = params[:guest][:text].to_s

                @guests_session = session[:guests]

                if session[:guests].nil?
                    @guests_session = [{:name => 'temp', :text => 'temp'}]
                else
                    logger.debug @guests_session
                    @guests_session.push({:name => name, :text => text})
                end

                session[:guests] = @guests_session
                redirect_to guests_path
        end
    end

    def display_data(display_method)
        case display_method
            when "db"
                @guests = Guest.all
            when "session"
                if session[:guests].nil?
                    @guests_session = [{:name => 'temp', :text => 'temp'}]
                else
                    #@guests_session = [{:name => 'temp', :text => 'temp'}]
                    @guests_session = session[:guests]
                end
        end
    end
end

Now when I open the corresponding view I get this error:

TypeError in GuestsController#index wrong argument type Class (expected Module)

With stacktrace:

app/controllers/guests_controller.rb:2:in `include'
app/controllers/guests_controller.rb:2:in `<class:GuestsController>'
app/controllers/guests_controller.rb:1:in `<top (required)>'
activesupport (4.1.5) lib/active_support/dependencies.rb:443:in `load'
activesupport (4.1.5) lib/active_support/dependencies.rb:443:in `block in load_file'
activesupport (4.1.5) lib/active_support/dependencies.rb:633:in `new_constants_in'
activesupport (4.1.5) lib/active_support/dependencies.rb:442:in `load_file'
activesupport (4.1.5) lib/active_support/dependencies.rb:342:in `require_or_load'
activesupport (4.1.5) lib/active_support/dependencies.rb:480:in `load_missing_constant'
activesupport (4.1.5) lib/active_support/dependencies.rb:180:in `const_missing'
activesupport (4.1.5) lib/active_support/inflector/methods.rb:238:in `const_get'
activesupport (4.1.5) lib/active_support/inflector/methods.rb:238:in `block in constantize'
activesupport (4.1.5) lib/active_support/inflector/methods.rb:236:in `each'
activesupport (4.1.5) lib/active_support/inflector/methods.rb:236:in `inject'
activesupport (4.1.5) lib/active_support/inflector/methods.rb:236:in `constantize'
activesupport (4.1.5) lib/active_support/dependencies.rb:552:in `get'
activesupport (4.1.5) lib/active_support/dependencies.rb:583:in `constantize'
actionpack (4.1.5) lib/action_dispatch/routing/route_set.rb:78:in `controller_reference'
actionpack (4.1.5) lib/action_dispatch/routing/route_set.rb:68:in `controller'
actionpack (4.1.5) lib/action_dispatch/routing/route_set.rb:46:in `call'
actionpack (4.1.5) lib/action_dispatch/journey/router.rb:71:in `block in call'
actionpack (4.1.5) lib/action_dispatch/journey/router.rb:59:in `each'
actionpack (4.1.5) lib/action_dispatch/journey/router.rb:59:in `call'
actionpack (4.1.5) lib/action_dispatch/routing/route_set.rb:678:in `call'
warden (1.2.3) lib/warden/manager.rb:35:in `block in call'
warden (1.2.3) lib/warden/manager.rb:34:in `catch'
warden (1.2.3) lib/warden/manager.rb:34:in `call'
rack (1.5.2) lib/rack/etag.rb:23:in `call'
rack (1.5.2) lib/rack/conditionalget.rb:25:in `call'
rack (1.5.2) lib/rack/head.rb:11:in `call'
actionpack (4.1.5) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.1.5) lib/action_dispatch/middleware/flash.rb:254:in `call'
rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.1.5) lib/action_dispatch/middleware/cookies.rb:560:in `call'
activerecord (4.1.5) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.1.5) lib/active_record/connection_adapters/abstract/connection_pool.rb:621:in `call'
activerecord (4.1.5) lib/active_record/migration.rb:380:in `call'
actionpack (4.1.5) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.1.5) lib/active_support/callbacks.rb:82:in `run_callbacks'
actionpack (4.1.5) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.1.5) lib/action_dispatch/middleware/reloader.rb:73:in `call'
actionpack (4.1.5) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
actionpack (4.1.5) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.1.5) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.1.5) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.1.5) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.1.5) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.1.5) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.1.5) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.1.5) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.1.5) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
rack (1.5.2) lib/rack/runtime.rb:17:in `call'
activesupport (4.1.5) lib/active_support/cache/strategy/local_cache_middleware.rb:26:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
actionpack (4.1.5) lib/action_dispatch/middleware/static.rb:64:in `call'
rack (1.5.2) lib/rack/sendfile.rb:112:in `call'
railties (4.1.5) lib/rails/engine.rb:514:in `call'
railties (4.1.5) lib/rails/application.rb:144:in `call'
passenger (4.0.50) lib/phusion_passenger/rack/thread_handler_extension.rb:74:in `process_request'
passenger (4.0.50) lib/phusion_passenger/request_handler/thread_handler.rb:141:in `accept_and_process_next_request'
passenger (4.0.50) lib/phusion_passenger/request_handler/thread_handler.rb:109:in `main_loop'
passenger (4.0.50) lib/phusion_passenger/request_handler.rb:455:in `block (3 levels) in start_threads'

I am basically just trying to learn how to use concerns with controllers. I want to seperate a big chuck of my code and put it into a corresponding concern to keep the controller nice and clean.

There is not much to find when googling or searching SO for concerns with controllers so I made this new question in hopes to get help.

So how could this issue be fixed and what am I doing wrong?

Answer 1

You've made a simple typo in your Data concern - it should be extend ActiveSupport::Concern (note the double colon, which is the namespace separator in Ruby).

Answer 2

You have encounter a name conflict - Data class exists in core Ruby: link here. This means that Rails will not initiate const_missing and your concern is never loaded. Rename your concern to DateModule or sth similar.