require 'attachment_helper' AttachmentHelper.attachment_host = 'http://myhost.com' class Topic include AttachmentHelper has_attachments [:logo_path, {size: '100x100'}], :pdf_path, :image_paths def logo_path 'uploads/a.png' end def pdf_path 'http://hello.com/assets/a.pdf' end def image_paths ['a.png', 'http://other.com/b.png'] end end topic = Topic.new puts topic.logo_url puts topic.logo_url(size: 200, t: 123) puts topic.logo_filename puts topic.pdf_url puts topic.pdf_url(foo: :bar) puts topic.pdf_filename puts topic.image_urls.inspect puts topic.image_urls(a: :foo).inspect puts topic.image_filenames.inspect