Support rendering CSV content directly as an attachment

csv_renderer.rb

# Save this in config/initializers/csv_renderer.rb

ActionController::Renderers.add :csv do |obj, options|
  filename = options[:filename] || 'data.csv'
  str = obj.respond_to?(:to_csv) ? obj.to_csv : obj.to_s
  send_data str,
            type: Mime::CSV,
            disposition: "attachment",
            filename: filename
end

#### USAGE: ####

class WidgestsControoller < ApplicationController 
  def index
    respond_to do |format|
      format.csv { render csv: Widget.all, filename: 'widgets.csv' }
      format.all { render }
    end
  end
end