Streaming Large Data Responses with Rails

I recently needed to stream a large CSV from a reporting interface and the streaming docs in Rails are mostly geared towards streaming template rendering. This allows you to stream any response object that responds to #each and can be used in any class that extends ActionController::Metal

class StreamingController < ApplicationController
  def index
    headers['X-Accel-Buffering'] = 'no' # Stop NGINX from buffering
    headers["Cache-Control"] = "no-cache" # Stop downstream caching
    headers["Transfer-Encoding"] = "chunked" # Chunked response header
    headers.delete("Content-Length") # See one line above

    # Anything that responds to #each can be used for a response_body
    self.response_body = Enumerator.new do |lines|
      # Uses ActiveRecord Batch API to find records efficently
      Model.find_each do |record|
        lines << record.to_csv
      end
    end
  end
end