Simple activeadmin export full table csv using a sidekiq background worker

active_admin_export_worker.rb

# app/workers/active_admin_export_worker.rb
class ActiveAdminExportWorker
  include Sidekiq::Worker
  sidekiq_options queue: 'high'

  def perform(options = {})
    model = options[:model_name].classify.constantize
    path = "#{Rails.root.to_s}/tmp/#{filename(options[:name])}"

    columns = model.send(:column_names)

    CSV.open(path, 'wb', headers: true) do |csv|
      csv << columns

      model.select(columns).find_each do |m|
        csv << m.attributes.values
      end
    end
  end

  private

  def filename(model)
    [model.to_s.try(:downcase), Time.current.try(:to_i)].join('_') + '.csv'
  end
end

active_admin_extensions.rb

# config/initializers/active_admin_extensions.rb
# Simple modified version of https://gist.github.com/stereoscott/6996507
module ActiveAdmin
  module Reports
    module DSL
      def enable_reports
        action_item only: :index do
          link_to 'Download', { action: :download, params: params }, { method: :post, data: { confirm: 'Are you sure you want to generate this report?' } }
        end

        collection_action :download, method: :post do
          options = {
            name: resource_class.to_s.pluralize,
            model_name: resource_class.to_s,
            email: current_admin_user.email
          }

          # User perform_later or perform_now for new versions of sidekiq          
          ActiveAdminExportWorker.perform_async(options)
          redirect_to :back
        end
      end
    end
  end
  ActiveAdmin::ResourceDSL.send :include, ActiveAdmin::Reports::DSL
end

users.rb

# app/admin/users.rb
# Add "enable_reports" to which ever activeadmin resource you want, this will add the download link on the top right
ActiveAdmin.register User do
  enable_reports
end