Rake task helping to migrate a rails 3 app to rails 4 with 'strong_parameters' instead of 'attr_accessible'

strong_parameters.rake

# Rake task to help migrating a rails 3 app to rails 4 strong_parameters.
# The task generates source code for helper methods for each model class
# to 'permit' the attributes.
# The generated methods are intended as starting point to copy&paste in the
# controller and than edit the permitted attributs.
# Some common names of non-editable attributes are already filtered,
# like 'id', 'password' or 'created_at'.
# The output is written to stdout so you can pipe it into a file
#
# Dependencies:
#   - rails-erd gem is used to access the models and attributes.
#
# Setup:
#   - $ rails generate task strong_parameters
#   - copy source into file lib/tasks/strong_parameters.rake
#   - add to development group in Gemfile:
#       gem 'rails-erd'
#
# Usage:
#   - $ rake controller:strong_methods > tmp/strong_parameter_methods.rb

require "rails_erd/domain"

namespace :controller do
  desc "generate strong parameter helper methods from model attributes"
  task strong_methods: [:environment, "erd:load_models"] do

    domain = RailsERD::Domain.generate # Discover all models that are currently loaded...

    puts "# Strong parameters template methods. Copy&paste into your controllers and adjust."
    puts
    domain.entities.each do |entity|
      puts "# #{entity.name} strong parameter helper method"
      if entity.model
        param_key = ActiveModel::Naming.param_key(entity.model)
        puts "def #{param_key}_params"
        puts "  params.require(:#{param_key})."
        param_list = entity.attributes.reject do |attribute|
          attribute.to_s =~ /id|type|created_at|updated_at|_token$|_count$/
        end.map do | attribute|
           ':' + attribute.to_s
        end
        puts "    permit(#{param_list.join(', ')})"
        unless entity.model.nested_attributes_options.empty?
          puts "# @TODO: check nested attributes for #{entity.model.nested_attributes_options.keys.join(', ')} "
        end
        puts "end"
        puts
      end
    end
  end
end