dump paperclip attachment urls to json

paperclip_attachments_to_json.rb

module PaperclipAttachmentsToJSON
  module ClassMethods
    def has_attached_file_with_explicit_urls(name, options = {})
      has_attached_file_without_explicit_urls(name, options)

      # explicit url method definition
      url_method = <<-EOM
      def %{name}_%{style}_url   # def avatar_original_url
        %{name}.url(:%{style})   #   avatar.url(:original)
      end                        # end
      EOM

      config = Paperclip::Attachment.default_options.merge(options)

      # define url accessor for default style
      module_eval(url_method % {:name => name, :style => config[:default_style]})

      # define url accessors for each custom styles
      config[:styles].each do |style, params|
        module_eval(url_method % {:name => name, :style => style})
      end
    end
  end

  module InstanceMethods
    def to_json_with_attachments(options = {})
      options[:methods] ||= []

      # enumerate all attachment definitions for the model
      self.class.attachment_definitions.each do |key, config|
        config = Paperclip::Attachment.default_options.merge(config)
        # append default style url accessor
        options[:methods] << "#{key}_#{config[:default_style]}_url".to_sym
        # append custom sryles url accessors
        config[:styles].each do |style, params|
          options[:methods] << "#{key}_#{style}_url".to_sym
        end
      end
      to_json_without_attachments(options)
    end

    alias_method_chain :to_json, :attachments
  end
end

ActiveRecord::Base.class_eval do
  extend PaperclipAttachmentsToJSON::ClassMethods
  include PaperclipAttachmentsToJSON::InstanceMethods
  class << self
    alias_method_chain :has_attached_file, :explicit_urls
  end
end