http://blog.base2.io/2012/11/30/seeding-with-progress/

genre.rb

class Genre < ActiveRecord::Base
  attr_accessible :name
end

genres.csv

name
TV Action & Adventure
TV Comedies
TV Dramas
Reality TV
Action & Adventure
Anime
Children & Family Movies
Classic Movies
Comedies
Documentaries
Dramas
Foreign Movies
Gay & Lesbian Movies
Horror Movies
Independent Movies
Romantic Movies
Sci-Fi & Fantasy
Sports Movies
Thrillers

seeds.rb

require 'csv'

def seed_from_csv(relative_path, label, has_headers = true)
  # Read in the CSV file:
  CSV.read(Rails.root.join(relative_path), headers: has_headers).tap do |csv|
    print "Seeding #{label}:\n"
    
    # For each row in the CSV:
    csv.each_with_index do |row, idx|
      # Do whatever behavior is required to seed.
      yield row if block_given?

      ratio = (idx + 1).to_f / csv.size
      per70 = (ratio * 70).round

      filled = per70 < 2 ? 0 : (per70 - 1)
      unfilled = 70 - per70
      pad_percentage = ("%.2f" % (ratio * 100)).rjust(6)

      progress = "%s%% [%s>%s]" % [ pad_percentage, ("=" * filled), (" " * unfilled) ]

      # Update the progress bar display for the user.
      print "\r#{progress}"
    end
    print "\n"
  end
end

# Seed Genre data from associated CSV file.
seed_from_csv("db/seeds/genres.csv", "Genre") { |row| Genre.create!(name: row[0]) }