ActionController::RoutingError (Couldn't find..., expected it to be defined in...) - actioncontroller

Question

So...first time asking a question to StackOverflow...
I converted an existing Rails 4.2.5 app (using Ruby 2.2.4) to a Rails 5.1.3 app (using Ruby 2.4.1), following the Rails Guides and the RailsApps Project.
Firing up the development server produces:
Taruns-iMac:Play_Ball tarunchattoraj$ rails s
=> Booting Puma
=> Rails 5.1.3 application starting in development on http://localhost:3000
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.9.1 (ruby 2.4.1-p111), codename: Private Caller
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://0.0.0.0:3000
Use Ctrl-C to stop
which is what I would expect.
Navigating to localhost:3000, however, produces an the ActionController error:
Started GET "/" for 127.0.0.1 at 2017-08-13 11:05:38 -0400
(0.2ms) SELECT "schema_migrations"."version" FROM "schema_migrations" ORDER BY "schema_migrations"."version" ASC
ActionController::RoutingError (Couldn't find Api::KeepScoresHelper, expected it to be defined in helpers/api/keep_scores_helper.rb):
app/controllers/application_controller.rb:1:in `<top (required)>'
app/controllers/welcome_controller.rb:1:in `<top (required)>'
I expected to see my app running on the page normally.
My Question:
What is causing this ActionController::RoutingError (Couldn't find...) and how to correct it?
This question seems to be on point. I tried the solution of "touching" all the helper files but to no avail.
When I converted from Rails 4.2.5 to 5.1.3, I ran $ rails app:update and I overwrote most files--those in which I didn't have code specific to my app, but I chose not to overwrite config/routes.rb.
config/routes.rb:
Rails.application.routes.draw do
resources :alerts
get 'games/decide_game_view' => 'games#decide_game_view', as: :decide_game_view
resources :games
resources :game_hitting_stats
resources :game_pitching_stats
resources :locations
resources :players
get 'welcome/index'
get 'welcome/about'
resources :users do
resources :players
end
resources :sessions, only: [:new, :create, :destroy]
resources :teams do
resources :notes
end
# namespace :api, defaults: {format: :http} do
namespace :api do
match '/texts', to: 'texts#preflight', via: [:options]
resources :texts, only: [:create]
match '/keepscore/teams', to: 'keep_scores#preflight', via: [:options]
get 'keepscore/teams' => 'keep_scores#get_teams', as: :get_teams
match '/keepscore/roster', to: 'keep_scores#preflight', via: [:options]
get 'keepscore/roster' => 'keep_scores#get_roster', as: :get_roster
match '/keepscore/post_game_stats', to: 'keep_scores#preflight', via: [:options]
post 'keepscore/post_game_stats' => 'keep_scores#post_game_stats', as: :post_game_stats
end
# The priority is based upon order of creation: first created -> highest priority.
# See how all your routes lay out with "rake routes".
# You can have the root of your site routed with "root"
# root 'welcome#index'
# Example of regular route:
# get 'products/:id' => 'catalog#view'
# Example of named route that can be invoked with purchase_url(id: product.id)
# get 'products/:id/purchase' => 'catalog#purchase', as: :purchase
# Example resource route (maps HTTP verbs to controller actions automatically):
# resources :products
# Example resource route with options:
# resources :products do
# member do
# get 'short'
# post 'toggle'
# end
#
# collection do
# get 'sold'
# end
# end
# Example resource route with sub-resources:
# resources :products do
# resources :comments, :sales
# resource :seller
# end
# Example resource route with more complex sub-resources:
# resources :products do
# resources :comments
# resources :sales do
# get 'recent', on: :collection
# end
# end
# Example resource route with concerns:
# concern :toggleable do
# post 'toggle'
# end
# resources :posts, concerns: :toggleable
# resources :photos, concerns: :toggleable
# Example resource route within a namespace:
# namespace :admin do
# # Directs /admin/products/* to Admin::ProductsController
# # (app/controllers/admin/products_controller.rb)
# resources :products
# end
root 'welcome#index'
end
ActionController seems to be telling me that it can't find the KeepScoresHelper Module and that its looking in helpers/api/keep_scores_helper.rb. But that file exists See Pic of App Controller and Helper Tree Structure.
The contents of helpers/api/keep_scores_helper.rb:
module API::KeepScoresHelper
end
Gemfile:
source 'https://rubygems.org'
ruby "2.4.1"
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '5.1.3'
gem 'puma'
gem 'pundit'
gem 'bcrypt'
gem 'active_model_serializers', '~> 0.10.0'
# Use SCSS for stylesheets
gem 'sass-rails', '~> 5.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# Use CoffeeScript for .coffee assets and views
gem 'coffee-rails', '~> 4.2.2'
# See https://github.com/rails/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby
# Use jquery as the JavaScript library
gem 'jquery-rails'
# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
gem 'turbolinks'
gem 'jquery-turbolinks'
gem 'bootstrap-sass'
gem 'figaro'
gem 'pry'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.0'
# bundle exec rake doc:rails generates the API under doc/api.
gem 'sdoc', '~> 0.4.0', group: :doc
# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'
# Use Unicorn as the app server
# gem 'unicorn'
# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development
group :production do
gem 'pg'
gem 'rails_12factor'
end
group :test do
gem 'pundit-matchers', '~>1.0.1'
end
group :development, :test do
# Call 'byebug' anywhere in the code to stop execution and get a debugger console
gem 'listen'
gem 'byebug'
gem 'web-console', '~> 3.5.1'
# Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
gem 'spring'
gem 'rspec-rails'
gem 'shoulda'
gem 'faker'
gem 'factory_girl_rails'
gem 'rails-controller-testing'
end
group :development do
# Access an IRB console on exception pages or by using <%= console %> in views
gem 'sqlite3'
end
Of course any help is greatly appreciated...

Answer 1

In config/environments/development.rb, set:
config.action_controller.include_all_helpers = false
This returns Helpers to pre-Rails 5 behavior. Per RoR API, for Rails 5.1.3, "By default, each controller will include all helpers." Pre Rails 5, the controller would include a helper matched to its name. Making the setting as specified above returns to the Pre-Rails 5 behavior.

Answer 2

Adding in hopes of helping others that stumble across this.
Initial Trouble Shooting
I had this same issue when upgrading the same versions you mention in your question. I did upgrade from 4.2 to 5.0 first though then upgrade to 5.1.3 from there.
The first upgrade worked fine but I started receiving the same error message (e.g. uninitialized constant ActionController::RedirectBackError ... about not being able to find the helpers but this only happened when I jumped to rails 5.1.
I tried a lot of other fixes as outlined in this github issue as it seemed to be the same error but nothing worked and my paths all seemed to be correct (no discrepancies in path or casing).
My Fix
I ended up deleting all helpers and received a new error which lead me to finding the code in my app that was causing the problem.
# app/controllers/application_controller.rb
# Catch exceptions if :back is not set throughout the app. This is a fallback redirect if request.referer is not set.
rescue_from ActionController::RedirectBackError do |exception|
redirect_to key_activities_ministries_activities_path, alert: exception.message
end
That code was causing a Routing Error: uninitialized constant ActionController::RedirectBackError. But this error only appeared when I removed all of my helpers. I removed this code, put my helpers back, and restarted my server and everything worked as expected.