http://stephencelis.com/2008/09/06/rails-controllers-views-and-variables.html

articles_controller.rb

class ArticlesController < ActionController::Base

  helper_method :articles, :article

  # render index, show, new, edit

  def create
    article.save!
    redirect_to articles_path
  end

  def update
    article.update_attributes! params[:article]
    redirect_to articles_path
  end

  def destroy
    article.destroy
    redirect_to articles_path
  end

  private

  def articles
    @articles ||= Article.all
  end

  def article
    @article ||= if params[:id]
      Article.find params[:id]
    else
      Article.new params[:article]
    end
  end

end