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

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 mongoid-paperclip gem inside your Gemfile. Additionally, you can define the aws-s3 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 mongoid-paperclip.

Rails.root/Gemfile - Just define the following:

gem "mongoid-paperclip", :require => "mongoid_paperclip" gem "aws-s3", :require => "aws/s3" 

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 Mongoid::Paperclip module and invoke the provided class method

class User include Mongoid::Document include Mongoid::Paperclip has_mongoid_attached_file :avatar end 

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

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

class User include Mongoid::Document embeds_many :pictures end class Picture include Mongoid::Document include Mongoid::Paperclip embedded_in :user, :inverse_of => :pictures has_mongoid_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 

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

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