License: MIT

Language: Ruby


Dragonfly is a Rack framework for on-the-fly image handling.

Ideal for using with Ruby on Rails (2.3 and 3), Sinatra and all that gubbins.

However, Dragonfly is NOT JUST FOR RAILS, and NOT JUST FOR IMAGES!!

IMPORTANT: if you're running a version between 0.7.0 and 0.9.12, please update to at least 0.9.14 for a security update details here

For the lazy Rails user...


gem 'rack-cache', :require => 'rack/cache'
gem 'dragonfly', '~>0.9.15'

Initializer (e.g. config/initializers/dragonfly.rb):

require 'dragonfly/rails/images'


add_column :albums, :cover_image_uid,  :string
add_column :albums, :cover_image_name, :string  # Optional - only if you want urls
                                                # to end with the original filename


class Album < ActiveRecord::Base
  image_accessor :cover_image            # 'image_accessor' is provided by Dragonfly
                                         # this defines a reader/writer for cover_image
  # ...

View (for uploading via a file field):

<% form_for @album, :html => {:multipart => true} do |f| %>
  <%= f.file_field :cover_image %>
<% end %>


You can avoid having to re-upload when validations fail with

<%= f.hidden_field :retained_cover_image %>

remove the attachment with

<%= f.check_box :remove_cover_image %>

assign from some other url with

<%= f.text_field :cover_image_url %>

and display a thumbnail (on the upload form) with

<%= image_tag @album.cover_image.thumb('100x100').url if @album.cover_image_uid %>

View (to display):

<%= image_tag @album.cover_image.url %>
<%= image_tag @album.cover_image.thumb('400x200#').url %>
<%= image_tag @album.cover_image.jpg.url %>
<%= image_tag @album.cover_image.process(:greyscale).encode(:tiff).url %>

The above relies on imagemagick being installed. Dragonfly doesn't depend on it per se, but the default configuration 'dragonfly/rails/images' uses it. For alternative configurations, see below.

If using Capistrano with the above, you probably will want to keep the cache between deploys, so in deploy.rb:

namespace :dragonfly do
  desc "Symlink the Rack::Cache files"
  task :symlink, :roles => [:app] do
    run "mkdir -p #{shared_path}/tmp/dragonfly && ln -nfs #{shared_path}/tmp/dragonfly #{release_path}/tmp/dragonfly"
after 'deploy:update_code', 'dragonfly:symlink'

Sinatra, CouchDB, Mongo, Rack, S3, custom storage, processing, and more...

Dragonfly is not just for Rails - it's primarily a Rack app, so you can use it as a standalone app, or with Sinatra, Merb, etc.

It's highly customizable, and works with any data type (not just images).

For more info, consult the DOCUMENTATION


For third-party add-ons, see the Add-ons wiki


Please use the github issue tracker if you have any issues.


Google group dragonfly-users



Copyright (c) 2009-2010 Mark Evans. See LICENSE for details.

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Recent Tags See all

v0.9.15-4 April 28, 2015
v0.9.15-3 April 28, 2015
v0.9.15-1 April 23, 2015
v1.0.7 August 26, 2014
v1.0.6 August 22, 2014
v1.0.5 May 15, 2014
v1.0.4 April 11, 2014
v1.0.3 January 28, 2014
v1.0.2 December 20, 2013
v1.0.1 November 28, 2013
v1.0.0 November 24, 2013
v0.9.15 May 04, 2013
v0.8.6 March 26, 2013
v0.9.14 February 13, 2013
v0.9.13 January 30, 2013

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