make_seed_data.rb

# quick class to create seed data from an existing model
# http://intridea.com/2008/4/20/seed-fu-simple-seed-data-for-rails
# sd = MakeSeedData.new(MyActiveRecord)
# sd.generate # get all records
# sd.generate(MyActiveRecord.all(:conditions => ...))
#
# Generate returns a string, put it in a file in db/fixtures as per their
# instructions. It can be passed any array of objects that can pretend to be
# the base active records
#
# You can ignore columns by passing an array of symbols to the initialize 
# method (defaults to created_at and updated_at)
#
# Enjoy
class MakeSeedData
  attr_reader :column_names
  attr_reader :seed_class
  def initialize(seed_class, except = [:created_at,:updated_at])
    @column_names = { }
    seed_class.columns.each do |col|
      name = col.name.to_sym
      @column_names[name] = col.type unless except.include?(name)
    end
    @seed_class = seed_class
  end
  def generate(scope = nil)
    output = ""
    output << "# seed for #{seed_class.name}\n"
    scope = seed_class.all unless scope
    scope.each do |row|
      output << "\n#{seed_class.name}.seed do |s|\n"
      column_names.each_pair do |name,type|
        output << "  s.#{name.to_s} = #{format_to_type(row[name],type)}\n"
      end
      output << "end\n"
    end
    output
  end
  def format_to_type(value,type)
    # puts "#{value},#{type}"
    return "nil" unless value
    case type
    when :string, :text
      escaped_value = value.gsub(/"/,'\"').gsub(/\#\{/,'\#{')
      "\"#{escaped_value}\""
    when :date,:datetime
      dt = value.to_time
      "DateTime.new(#{dt.year},#{dt.month},#{dt.day},#{dt.min},#{dt.sec})"
    else
      value
    end
  end
end