Dynamoid::Paperclip - Making Paperclip play nice with Dynamoid

As the title suggests: Dynamoid::Paperclip makes it easy to hook up Paperclip with Dynamoid.

This is actually easier and faster to set up than when using Paperclip and the ActiveRecord ORM. This example assumes you are using Ruby on Rails 3 and Bundler. However, it doesn't require either.

Simply define the dynamoid-paperclip gem inside your Gemfile. Additionally, you can define the aws-sdk gem if you want to upload your files to Amazon S3. You do not need to explicitly define the paperclip gem itself, since this is handled by dynamoid-paperclip.

Rails.root/Gemfile - Just define the following:

gem 'dynamoid-paperclip'
gem 'aws-sdk'

Next let's assume we have a User model and we want to allow our users to upload an avatar.

Rails.root/app/models/user.rb - include the Dynamoid::Paperclip module and invoke the provided class method

class User
  include Dynamoid::Document
  include Dynamoid::Paperclip

  has_dynamoid_attached_file :avatar
end

That's all you have to do. Users can now upload avatars. Unlike ActiveRecord, Dynamoid doesn't use migrations, so we don't need to define the Paperclip columns in a separate file. Invoking the has_dynamoid_attached_file method will automatically define the necessary :avatar fields for you in the background.

Just like Paperclip, Dynamoid::Paperclip takes a second argument (hash of options) for the has_dynamoid_attached_file method, so you can do more complex things such as in the following example.

class User
  include Dynamoid::Document
  embeds_many :pictures
end

class Picture
  include Dynamoid::Document
  include Dynamoid::Paperclip

  embedded_in :user, :inverse_of => :pictures

  has_dynamoid_attached_file :attachment,
    :path           => ':attachment/:id/:style.:extension',
    :storage        => :s3,
    :url            => ':s3_alias_url',
    :s3_host_alias  => 'something.cloudfront.net',
    :s3_credentials => File.join(Rails.root, 'config', 's3.yml'),
    :styles => {
      :original => ['1920x1680>', :jpg],
      :small    => ['100x100#',   :jpg],
      :medium   => ['250x250',    :jpg],
      :large    => ['500x500>',   :jpg]
    },
    :convert_options => { :all => '-background white -flatten +matte' }
end

@user.pictures.each do |picture|
  <%= picture.attachment.url %>
end

Note on embedded documents: if you plan to save or update the parent document, you MUST add cascade_callbacks: true to your embeds_XXX statement. Otherwise, your data will be updated but the paperclip functions will not run to copy/update your file.

In the above example:

class User
  ...
  embeds_many :pictures, :cascade_callbacks => true
  accepts_nested_attributes_for :pictures, ...
  attr_accepted :pictures_attributes, ...
  ...
end

@user.update_attributes({ ... :pictures => [...] })

Quite a lot of people have been looking for a solution to use Paperclip with Dynamoid so I hope this helps!

If you need more information on either Dynamoid or Paperclip I suggest checking our their official documentation and website.

dynamoid-paperclip borrows code, structure, and even its name very liberally from mongoid-paperclip. Without mongoid-paperclip to crib from, none of this would have been possible. Therefore, many thanks to everyone who contributed to mongoid-paperclip.

Dynamoid::Paperclip is released under the MIT license. See LICENSE for more information.