Example of rake task that migrates production data

questions.rake

namespace :question do

  desc "Update Questions and Tasks to support newly added validations"
  task :update_for_validations => :environment do
    ActiveRecord::Base.transaction do
      # Set question_type to "yesno" for following questions:
      %w(need_long_term_rental need_short_term_rental find_eye_doctor cleaning need_home).each do |identifier|
        q = Question.find_by_identifier(identifier)
        q.update_attributes!(question_type: "yesno") if q.present?
      end

      # Delete 6 tasks with name "Master Question - NO TASK"
      master_question_tasks = Task.where(name: "Master Question - NO TASK")
      master_question_tasks.each(&:destroy!)
    end

    puts "Verifying validity of remaining questions..."
    all_questions_valid = true
    Question.find_each do |q|
      unless q.valid?
        puts "Invalid question: [#{q.id}/#{q.identifier}] #{q.errors.full_messages}"
        all_questions_valid = false
      end
    end
    puts "All Questions are valid." if all_questions_valid

    puts "Verifying validity of remaining tasks..."
    all_tasks_valid = true
    Task.find_each do |t|
      unless t.valid?
        puts "Invalid task: [#{t.id}/#{t.name}] #{t.errors.full_messages}"
        all_tasks_valid = false
      end
    end
    puts "All Tasks are valid" if all_tasks_valid
  end
  
end