Basic Formtastic Input for working with Paperclip image attachments

paperclip_image_input.rb

class PaperclipImageInput < Formtastic::Inputs::FileInput
  def image_html_options
    {:class => 'attachment'}.merge(options[:image_html] || {})
  end

  def to_html
    input_wrapping do
      label_html <<
      image_html <<
      builder.file_field(method, input_html_options)
    end
  end

protected

  def image_html
    attachment = builder.object.send(method)
    if builder.object.new_record? || attachment.nil?
      return "".html_safe
    end

    style = options.fetch(:style, :thumb)
    url = attachment.url(style)

    builder.template.image_tag(url, image_html_options).html_safe
  end
end