Dragonfly and Short URLs - ruby-on-rails

Question

I'm using Dragonfly in a project that returns a large stream of photos and was looking to optimize the URLs. I'm currently getting image URLs like:
http://localhost:3000/media/BAhbCFsHOgZmSSJgZmRlL2ZkZTAxYzQ0LTM4Y2UtNGU0ZS1iOWRlLWUwZmUxNWUwN2JmMC83Mzk1NmZlMC05ZTA5LTQzNWUtODUyMC00MzFlYzQxMzQ1OTQvb3JpZ2luYWwuanBlZwY6BkVUWwg6BnA6CnRodW1iSSIMMjQweDI0MAY7BkZbCTsHOgxjb252ZXJ0SSIQLXF1YWxpdHkgODAGOwZGMA/240x240.jpg
Which is over 256 bytes. I'd like something like:
http://localhost:3000/media/1024/240x240_medium.jpg
That is conforming to:
/media/:id/:format
How would I go about adding this when using Dragonfly and Rails such that :format maps to a chain of operations and :id is used to find the model or image? Thanks!
Edit:
I've added custom Mime::Typefor each of the formats I need and have the following working:
# config/routes.rb
match "/photos/:id/:style", to: "photos#show", as: :media
# app/controllers/photos_controller.rb
def show
#photo = Photo.find(params[:id])
respond_to do |format|
format.html # show.html.erb
format.jpg { cache('public', 86400); redirect_to #photo.url(params[:style], 'jpg') }
format.png { cache('public', 86400); redirect_to #photo.url(params[:style], 'png') }
format.gif { cache('public', 86400); redirect_to #photo.url(params[:style], 'gif') }
end
end
# app/views/photos/show.html.erb
<%= image_tag media_path(id: #photo.id, style: 'small', format: 'png') %>
However this results in a 302 for each image (but otherwise works fine). Is it possible to handle this as a render or somehow do an internal redirect (i.e. not require the client to make duplicate requests)?

Answer 1

you shouldn't need to use a controller action - you can use a dragonfly endpoint - see http://markevans.github.com/dragonfly/file.URLs.html#Routed_Endpoints
e.g.
match '/photos/:id/:style.:format' => Dragonfly[:images].endpoint { |params, app|
Photo.find(params[:id]).image.thumb(params[:style]).encode(params[:format])
}
or something like that
(haven't tried the above code but it'll be something along those lines)

Answer 2

I've ran into a similar situation where the client needed a short url for downloadable pdfs.
Building on Mark's answer and looking at the dragonfly docs I came up with this:
#file.rb
class File < ActiveRecord::Base
dragonfly_accessor :pdf
end
def pdf_link
return "/pdf/#{self.filename}.pdf"
end
#routes.rb
get '/pdf/:filename' => Dragonfly.app.endpoint { |params, app|
File.where(filename: params[:filename]).first.pdf
}
It's not a direct answer to the question, but maybe it can still help someone looking for a way to shorten urls in dragonfly