cryptcheck-rails/app/controllers/statistics_controller.rb

class StatisticsController < ApplicationController
  TODAY = Date.today

  def show
    service = params.fetch :id
    respond_to do |format|
      format.json do
        json = Stat.where(name: "grades_for_#{service}").order(date: :desc).last.dataset
        render json: json, status: :ok
      end
    end
  end
end