Paperclip - remove attachment

mode.rb

class Model < ActiveRecord::Base
  has_attached_file :icon
  
  has_removable_file :icon
end

removable_attachment.rb

module Paperclip
  module RemovableAttachment
    def self.included(base)
      base.extend(ClassMethods)
      base.send(:include, InstanceMethods)
    end

    module ClassMethods
      attr_reader :removable_attachments

      def has_removable_file(*attrs)
        attrs.each do |name|
          class_eval <<-METHOD, __FILE__, __LINE__
            attr_accessor :delete_#{name}

            def delete_#{name}=(value)
              @delete_#{name} = !value.to_i.zero?
            end

            def delete_#{name}
              !!@delete_#{name}
            end

            alias_method :delete_#{name}?, :delete_#{name}
          METHOD
        end

        @removable_attachments = attrs
        before_validation :clear_removable_attachment
      end
    end

    module InstanceMethods
      private
        def clear_removable_attachment
          self.class.removable_attachments.each do |name|
            self.send("#{name}=", nil) if self.send("delete_#{name}?") && !self.send(name).dirty?
          end
        end
    end
  end
end

removable_attachment_spec.rb

require 'spec_helper'
require 'active_record'

ActiveRecord::Schema.define do
  create_table "user_examples", :force => true do |t|
    t.string :avatar_file_name
  end
end

class Attachment
  attr_accessor :dirty
  def dirty?; @dirty; end
end

class UserExample < ActiveRecord::Base
  include Paperclip::RemovableAttachment

  attr_accessor :avatar
  has_removable_file :avatar
end

describe "Paperclip::RemovableAttachment" do
  before(:each) do
    a = Attachment.new
    a.dirty = true
    @u = UserExample.new(:avatar_file_name => 'avatar.png', :avatar => a)
  end

  it 'should respond to delete virtual attributes for each removable attachment' do
    @u.should respond_to('delete_avatar=')
    @u.should respond_to('delete_avatar')
    @u.should respond_to('delete_avatar?')
  end

  it 'should have removable attribute on list of removable attachments' do
    @u.class.removable_attachments.should include(:avatar)
  end

  it 'should remove attachment if delete attribute is 1 if attachment is new' do
    @u.avatar.dirty = false
    @u.avatar.should_not be_nil
    @u.update_attributes(:delete_avatar => "1")
    @u.avatar.should be_nil
  end

  it 'should not remove attachment with delete attribute setted to 1 if uploaded file changed' do
    @u.avatar.dirty = true
    @u.avatar.should_not be_nil
    @u.update_attributes(:delete_avatar => "1")
    @u.avatar.should_not be_nil
  end

  it 'should not remove attachment if delete attribute is 0' do
    @u.avatar.dirty = true
    @u.avatar.should_not be_nil
    @u.update_attributes(:delete_avatar => "0")
    @u.avatar.should_not be_nil
  end
end