Changing scaffold-controller-generator-templates in Rails

Question

When I use the Rails scaffold generator to create my Rails-files, it creates among others a controller file. e.g.

rails generate scaffold potato

generates:

app/controllers/potatos_controller.rb

For my project I want this file a little more specific. E.g. I want to change this automatic generated action:

def create
  @potato = Potato.new(potato_params)

  respond_to do |format|
    if @potato.save
      format.html { redirect_to @potato, notice: 'Potato was successfully created.' }
      format.json { render :show, status: :created, location: @potato }
    else
      format.html { render :new }
      format.json { render json: @potato.errors, status: :unprocessable_entity }
    end
  end
end

to use a I18n-translation instead of the hardcoded 'Potato was successfully created.' Also I want to change some indentations, since rubocop is always complaining about it.

I have found the template of the scaffold-generator and now want to make my changes. For this I have created a file in my project: lib/templates/rails/scaffold_controller/templates/controller.rb In this file I have made my changes. (e.g. I changed the line

redirect_to @<%= singular_table_name %>, notice: <%= "'#{human_name} was successfully created.'" %>

to

redirect_to @<%= singular_table_name %>, notice: <%= "'#{human_name} THIS IS A TEST.'" %>

But unfortunately the changes don't work. The scaffold generator still uses its own template. So what am I doing wrong here? Am I missing a step?

Update: Here is the output of the generate-command:

rails generate scaffold potato      

Running via Spring preloader in process 31479
  invoke  active_record
  ...

  invoke  scaffold_controller
  create    app/controllers/potatos_controller.rb
  ...

Screenshot of the railties:

Answer 1

If anyone finds it useful, you can copy the default railties controller scaffold templates to your own project by running this command in your project directory:

mkdir -p lib/templates/rails/scaffold_controller && \
  cp $(bundle info railties --path)/lib/rails/generators/rails/scaffold_controller/templates/* \
  lib/templates/rails/scaffold_controller

If you use Rails 5.2 and jbuilder, you should use the jbuilder scaffolders as a base instead:

mkdir -p lib/templates/rails/scaffold_controller && \
  cp $(bundle info jbuilder --path)/lib/generators/rails/templates/* \
  lib/templates/rails/scaffold_controller

Answer 2

Rails 4 shows you which template is using

rails generate scaffold potato
...
invoke  scaffold_controller

You should host your modified templates in your project, i.e.
lib/templates/rails/scaffold_controller/controller.rb.

Please note that the Responders gem might change the generator used to
lib/templates/rails/responders_controller/controller.rb.