Merging one record into another - take care of all associated data.

mergeable models

module Mergeable
  def merge_associated_records_and_destroy(throwaway_object, special_cases = {})
    #look for any fields that match field name
    field_name_to_update = "#{self.class.to_s.downcase}_id"
    Dir[Rails.root.to_s + '/app/models/**/*.rb'].each { |file| require(file)}
    message = []
    models = ActiveRecord::Base.subclasses.collect
    begin
      models.each do |m|
        if m.columns_hash["#{self.class.to_s.downcase}_id"] 
          count = m.where(field_name_to_update.to_sym => throwaway_object.id).update_all(field_name_to_update.to_sym => self.id)
           message << "Updated #{count}: #{m} on #{field_name_to_update}"
        elsif special_cases[m]
          special_cases[m].each do |f|
            count = m.where(f.to_sym => throwaway_object.id).update_all(f => self.id)
            message << "Updated #{count}: #{m} on #{f}"
          end
        end
        #polymorphic, check if any polymorphics, and see if any types that match Class and ID
        m.reflect_on_all_associations.each do |relation|
          if relation.options[:polymorphic]
            count = m.where("#{relation.name}_type" => "#{self.class.to_s}", "#{relation.name}_id" => throwaway_object.id).update_all("#{relation.name}_id" => self.id)
            message << "Updated #{count}: polymorphic association on #{m} with #{relation.name}"
          end
        end
      end
      success_level = 'success'
      throwaway_object.destroy
    rescue Exception => e
      success_level = 'failure'
      message << e.message
    end
    return { :success_level => success_level, :message => message, :time_complete => Time.now, :resource_id => nil }  
  end
end