Make filter DRY

filter.rb

# How can I move the filter into a helper and make the Model name dynamic?

#Page controller
before_filter :published_or_authenticated, :only => [:show]

  def published_or_authenticated
    @page = Page.find(params[:id])
    if !user_signed_in? && @page.published == false
      raise ActionController::RoutingError.new('Not Found')
    end 
  end

#Post controller
before_filter :published_or_authenticated, :only => [:show]

  def published_or_authenticated
    @post = Post.find(params[:id])
    if !user_signed_in? && @post.published == false
      raise ActionController::RoutingError.new('Not Found')
    end 
  end