carrierwave delayed version processing

readme.md

All the versions declared as 'delayed' won't be processed synchronously. Instead they will be processed when you call ClientFile#process_delayed_versions!. It's up to you to decide when and from where to call this.

delayed_versions.rb

module Carrierwave
  module DelayedVersions
    extend ActiveSupport::Concern

    module ClassMethods
      def delayed_versions
        @delayed_versions ||= Set.new
      end

      def delayed_version(name, opts = {}, &block)
        delayed_versions.add(name)
        version(name, opts.merge(:if => :processing_async?), &block)
      end
    end

    def processing_async?(img = nil)
      !!model.processing_async
    end

    module ModelMethods
      extend ActiveSupport::Concern

      included { attr_accessor :processing_async }

      def with_async_processing
        self.processing_async = true
        yield
      ensure
        self.processing_async = false
      end

      def process_delayed_versions!
        self.class.uploaders.each do |mounted_as, uploader|
          next unless uploader.included_modules.include?(Carrierwave::DelayedVersions) &&
            !uploader.delayed_versions.empty?

          with_async_processing do
            send(mounted_as).send(:"recreate_versions!", *uploader.delayed_versions.to_a)
          end
        end
      end
    end
  end
en# # 

model_example.rb

class ClientFile < ActiveRecord::Base
  include Carrierwave::DelayedVersions::ModelMethods
  mount_uploader :preview, UploaderExample
end

uploader_example.rb

class ClientFilePreviewUploader < BaseUploader
  @fog_public = true

  include Carrierwave::DelayedVersions

  delayed_version :large do
    process :resize_to_fit => [768, 768]
    process :pad_to_exact_dimensions => [768, 768]
    process :apply_pngquant
  end

  delayed_version :medium do
    process :resize_to_fit => [384, 384]
    process :pad_to_exact_dimensions => [384, 384]
    process :apply_pngquant
  end

  delayed_version :small do
    process :resize_to_fit => [192, 192]
    process :pad_to_exact_dimensions => [192, 192]
    process :apply_pngquant
  end

  version :thumb do
    process :resize_to_fit => [100, 100]
    process :pad_to_exact_dimensions => [100, 100]
  end


  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end

  def extension_white_list
    %w(jpg jpeg png)
  end
end

Hello @rogercampos...thank you for this. But it can work with Mongoid?