sample.rb

class ProductsController < ApplicationController
  respond_to :html # Set in the ApplicationController

  before_filter :admin_user!
  before_action :set_product, only: [:edit, :update, :destroy]

  def index
    @products = Product.order :name

    respond_with @products
  end

  def new
    @product = Product.new

    respond_with @product
  end

  def edit; end

  def create
    @product = Product.new product_params
    @product.save

    respond_with @product, location: products_path
  end

  def update
    @product.update product_params

    respond_with @product, location: products_path
  end

  def destroy
    @product.destroy

    respond_with @product, location: products_path
  end

  private

  def set_product
    @product = Product.find params[:id]
  end

  def product_params
    params.require(:product).permit :name, :kind
  end

  def admin_user!
    raise MyCustomError if !current_user.admin?
  end
end