dumper.rb

class Dumper                                                                                                                                                                                     
  attr_accessor :object, :tables

  def initialize(object, tables=nil)
    @object = object
    @tables = tables || Hash.new {|hash,key| hash[key] = []} 
  end 

  def dump
    puts "Dumping #{object.class.name}##{object.id}"
    object.class.reflect_on_all_associations.each do |assoc|
      case assoc.macro
      when :has_many
        object.send(assoc.name).each do |child|
          if !tables[child.class.table_name].include?(child.id)
            tables[assoc.table_name] << child.id
            Dumper.new(child, tables).dump
          end 
        end 
      when :belongs_to
        child = object.send(assoc.name)
        if child && !tables[child.class.table_name].include?(child.id)
          tables[child.class.table_name] << child.id
          Dumper.new(child, tables).dump
        end 
      end 
    end 
    self
  end 

  def out 
    tables.each do |table, ids|
      puts "#{table}: #{ids}"
    end 
  end 
end