ETag + Conditional GET for JSON API

                  class Api::SnipsController < ActionController::API
  def show
    snip = Snip.includes(:author, :code_blocks).find(params[:id])

    if stale?(etag: [snip.cache_key_with_version, snip.code_blocks.maximum(:updated_at)], last_modified: snip.updated_at)
      render json: SnipSerializer.new(snip).as_json
    end
  end
end