Paperclip with MongoMapper in Rails 3

Question

I'm trying to implement Paperclip in my first rails app, and I happen to be using rails 3 and mongodb with mongomapper.

I followed this guide on getting there things to all work together

Just as the blog post suggests, I've put paperclip into the config/initializers directory, I installed the gem, the gem is in the gemfile (rails 3 right), I ran the bundler.

In my user class, I've added

require 'paperclip'

When I load the app, I get the following error,

undefined method 'has_attached_file' for User:Class

The paperclip file looks like this

module Paperclip
  module ClassMethods
    def has_attached_file name, options = {}
      include InstanceMethods

      write_inheritable_attribute(:attachment_definitions, {}) if attachment_definitions.nil?
      attachment_definitions[name] = {:validations => []}.merge(options)

      after_save :save_attached_files
      before_destroy :destroy_attached_files

      define_callbacks :before_post_process, :after_post_process
      define_callbacks :"before_#{name}_post_process", :"after_#{name}_post_process"

      define_method name do |*args|
        a = attachment_for(name)
        (args.length > 0) ? a.to_s(args.first) : a
      end

      define_method "#{name}=" do |file|
        attachment_for(name).assign(file)
      end

      define_method "#{name}?" do
        attachment_for(name).file?
      end

      validates_each name, :logic => lambda {
        attachment = attachment_for(name)
        attachment.send(:flush_errors) unless attachment.valid?
      }
    end
  end

  module Interpolations
    # Handle string ids (mongo)
    def id_partition attachment, style
      if (id = attachment.instance.id).is_a?(Integer)
        ("%09d" % id).scan(/\d{3}/).join("/")
      else
        id.scan(/.{3}/).first(3).join("/")
      end
    end
  end
end

Any suggestions on what I may be doing wrong? have I got the steps right?

Answer 1

As of MongoMapper 0.11.0, Paperclip 2.5.2, and Rails 3.0.4, all you need is:

#your model
require 'paperclip'

class User
  include MongoMapper::Document
  include Paperclip::Glue

  has_attached_file :avatar

  key :avatar_file_name, String
end

You don't need a Paperclip initializer anymore.

Answer 2

I just released a gem to take care of this after the above code snippets didn't quite work for later versions of paperclip and rails.

Check out mongomapper-paperclip