Newbie question: undefined local variable or method , why?

I am new in Rails (I am using Rails 3.0.3), currently I am following the book "Agile Web Development with Rails" to develop a simple rails application.

I followed the book to:

--create a model 'Cart' class;

--implement 'add_to_cart' method in my 'store_controller',

I have a line of code

<%=button_to "Add to Cart", :action => add_to_cart, :id => product %> in my /store/index.html.e开发者_开发百科rb

As you see, there is :action => add_to_cart in my index.html.erb, which will invoke the add_to_cart method in my *Controllers/store_controller.rb*

But after I refresh the browser, I got the error "undefined local variable or method 'add_to_cart'", apparently I do have the method add_to_cart in my 'store_controller.rb', why I got this error??? What is the possible cause???

Here are my codes:

store_controller.rb

    class StoreController < ApplicationController
      def index
        @products = Product.find_products_for_sale
      end



      def add_to_cart
        product = Product.find(params[:id]) 
        @cart = find_cart                   
        @cart.add_product(product)          
      end



    private

      def find_cart
        session[:cart] ||= Cart.new
      end


    end

/store/index.html.erb

<h1>Your Pragmatic Catalog</h1>

<% @products.each do |product| -%>
  <div class="entry">
    <%= image_tag(product.image_url) %>
    <h3><%=h product.title %></h3>
    <%= product.description %>
    <div class="price-line">
    <span class="price"><%= number_to_currency(product.price) %></span>
    <!-- START_HIGHLIGHT -->
    <!-- START:add_to_cart -->
    **<%= button_to 'Add to Cart', :action => 'add_to_cart', :id => product %>**
    <!-- END:add_to_cart -->
    <!-- END_HIGHLIGHT -->
    </div>
  </div>
<% end %>

Model/cart.rb

class Cart
  attr_reader :items   

  def initialize
    @items = []
  end

  def add_product(product)
    @items << product
  end
end

It seems like you're following an old version of the book (written with Rails 2 in mind), while trying to create a Rails3 application.

To simply add the route you need, add

match 'store/add_to_cart/:id' => 'store#add_to_cart'

Understanding RESTful applications is much more involved. Basically, you design your application so that it is made up of several resources you can create, update, delete, link, etc.

I strongly suggest picking up the latest version of "Agile Web Development with Rails" based on Rails3. It will clear things up for you (in particular, you'll see that on page 124, adding items to the cart in a RESTful way is managed differently).

I solved my problem by uncommend the

# This is a legacy wild controller route that's not recommended for RESTful applications.
# Note: This route will make all actions in every controller accessible via GET requests.
   match ':controller(/:action(/:id(.:format)))'

under Configuration / routes.rb

Then, there is another question I would like to ask, as the above configuration says, uncommanding this line is not recommended for RESTful applications, then what is the RESTful application solution for this problem???