# your_initializer.rb
require 'attribute_normalizer'
YourORM::Base.send :include, AttributeNormalizer

sudo gem install attribute_normalizer

# config/environment.rb
config.gem 'attribute_normalizer'

# Gemfile
gem 'attribute_normalizer'

./script/plugin install git://github.com/mdeering/attribute_normalizer.git

# spec/models/book_spec.rb
describe Book do
  it { should normalize_attribute(:author) }
  it { should normalize_attribute(:price).from('$3,450.98').to(3450.98) }
  it { should normalize_attribute(:summary).from('   Here is my summary that is a little to long   ').to('Here is m...') }
  it { should normalize_attribute(:title).from(' pick up chicks with magic tricks  ').to('Pick Up Chicks With Magic Tricks') }
  it { should normalize_attribute(:slug).from(' Social Life at the Edge of Chaos    ').to('social-life-at-the-edge-of-chaos') }
  it { should normalize_attribute(:limited_slug).from(' Social Life at the Edge of Chaos    ').to('social-life') }
end

# config/initializers/attribute_normalizer.rb
AttributeNormalizer.configure do |config|

  config.normalizers[:currency] = lambda do |value, options|
    value.is_a?(String) ? value.gsub(/[^0-9\.]+/, '') : value
  end

  config.normalizers[:truncate] = lambda do |text, options|
    if text.is_a?(String)
      options.reverse_merge!(:length => 30, :omission => "...")
      l = options[:length] - options[:omission].mb_chars.length
      chars = text.mb_chars
      (chars.length > options[:length] ? chars[0...l] + options[:omission] : text).to_s
    else
      text
    end
  end

  # The default normalizers if no :with option or block is given is to apply the :strip and :blank normalizers (in that order).
  # You can change this if you would like as follows:
  # config.default_normalizers = :strip, :blank

end

class Book < ActiveRecord::Base

  # By default it will strip leading and trailing whitespace
  # and set to nil if blank.
  normalize_attributes :author, :publisher

  # Using one of our predefined normalizers.
  normalize_attribute  :price, :with => :currency

  # Using more then one of our predefined normalizers including one with options
  normalize_attribute :summary, :with => [ :strip, { :truncate => { :length => 12 } } ]

  # You can also define your normalization block inline.
  normalize_attribute :title do |value|
    value.is_a?(String) ? value.titleize.strip : value
  end

  # Or use a combination of normalizers plus an inline block.
  # the normalizers in the :with option will each be evalulated
  # in order and the result will be given to the block.
  # You could also use option :before in place of :with
  normalize_attribute :slug, :with => [ :strip, :blank ] do |value|
    value.present? && value.is_a?(String) ? value.downcase.gsub(/\s+/, '-') : value
  end

  # Use builtin normalizers before and after the evaluation of your inline
  # block
  normalize_attribute :limited_slug, :before => [ :strip, :blank ], :after => [ { :truncate => { :length => 11, :omission => '' } } ] do |value|
    value.present? && value.is_a?(String) ? value.downcase.gsub(/\s+/, '-') : value
  end

end

summary = 'Here is my summary that is a little to long'
title   = 'pick up chicks with magic tricks'
book    = Book.create!(:author => '', :price => '$3,450.89', :summary => summary, :title => title, :slug => title, :limited_slug => title)
book.author       # => nil
book.price        # => 3450.89
book.summary      # => 'Here is m...'
book.title        # => 'Pick Up Chicks With Magic Tricks'
book.slug         # => 'pick-up-chicks-with-magic-tricks'
book.limited_slug # => 'pick-up-chi'

# spec/spec_helper.rb
RSpec.configure do |config|
  config.include AttributeNormalizer::RSpecMatcher, :type => :models
end

# spec/spec_helper.rb
RSpec.configure do |config|
  config.include AttributeNormalizer::RSpecMatcher, :type => :model
end