Carrierwave.md

Carrierwave

Information from @SicutDominus

Carrierwave gem.

By default Carrierwave uploads files into /public/uploads. Here is an example to merge all attachments on a standard user model into a single report file, stored in /tmp.

#models/user.rb
class User < ActiveRecord::Base
  has_many :attachments, dependent: :destroy
  accepts_nested_attributes_for :attachments, :allow_destroy => true
end

#config/routes.rb
get 'users/:id/report' => 'users#report', as: :users_report

#views/users/show.html.erb
<%= link_to 'Report', users_report_path(@user) %>

#app/controllers/users_controller.rb
def report
    failure_list = []
    pdf = PDF::Merger.new

    if @user.attachments.empty?
      flash[:error] = 'No attachments.'
    else
      for attachment in @user.attachments
        # Note the .to_s, otherwise code fails by passing a Ruby item rather than string into add_file
        pdf.add_file Rails.root.join("public#{attachment.file.to_s}").to_s
      end

      # Best to have some kind of unique identifier in the file name so they aren't constantly overwriting each other
      save_path = Rails.root.join('tmp', "report - #{@user.email}.pdf").to_s
      pdf.save_as(save_path, failure_list)
      # File now stored in tmp
      # Manipulate the file here (eg. send out via email), then uncomment the line below if you want it deleted.
      # Comment the line below to examine file for testing purposes
      #File.delete(save_path)

      flash[:notice] = 'Report successfully generated.'
    end

    redirect_to @user
  end