Hook into rails model generators to update a scope that requires changes each time a new model is added

hooks_generator.rb

# config/environments/development.rb

config.generators do |generator|
  generator.orm :hooks
end

# lib/generators/rails/hooks/hooks_generator.rb

require 'rails/generators/active_record/model/model_generator'

module Rails
  module Generators
    hide_namespace 'hooks'

    class HooksGenerator < ActiveRecord::Generators::ModelGenerator
      source_root "#{base_root}/active_record/model/templates"

      def create_fund_scoping_annotation
        model = Rails.root.join("app", "models", "fund.rb")
        line = 'scope :having_investments_in'
        gsub_file model, /(#{Regexp.escape(line)})/mi do |match|
          "#{match}_blown_up"
        end
        puts 'Please update fund scope :having_investments_in' \
             'Add relative scopes if needed and update :having_investments_in'
      end

      private

      def gsub_file(path, regexp, *args, &block)
        content = File.read(path).gsub(regexp, *args, &block)
        File.open(path, 'wb') { |file| file.write(content) }
      end
    end
  end
end