Question

I’m trying to integrate eCommerce functionality into my rails app, and am having trouble creating a new order. I start with a cart, which has_many orders, which has_many transactions. The first field in my order database is cart_id. I need to be able to access information in the cart (such as total_price) from the view/order/new.html.erb.

Where would be the best place to build this relation, and how? I can find the cart through the session id, but I don’t know how to build the relationship. I was thinking in the order model, in the new action, somthing like so?

  def new
    @order = Order.new
    [e-mail]

Defined in my application controller is the function current_cart

  def current_cart
    Cart.find(session[:cart_id])
  rescue ActiveRecord::RecordNotFound
    cart = Cart.create
    session[:cart_id] = cart.id
    cart
  end

UPDATE

Here is my new and create function, and where I need the value

  def new
    @order = Order.new
    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @order }
    end
  end

  # POST /orders
  # POST /orders.json
  def create
    @order = Order.new(params[:order])

       # THIS IS WHERE I HAVE TRIED TO BUILD THE RELATIONSHIP
       # I have tried current_cart.orders.build, @order.cart = current_cart, and 
       # @order = current_cart.build_order(params[:order])

    @order.ip_address = request.remote_ip
    if @order.save
      if @order.purchase
        render :action => "success"
      else
        render :action => "failure"
      end
    else
      render :action => 'new'
    end
  end

and this is where I need to access the cart in the model

  def price_in_cents
    (cart.total_price*100).round
  end

And I always get an exception caught for an undefined function, either the build function, or the total price function

Answer 1

In the Order model you have the cart_id, so define the relation there:

belongs_to :cart

You can also define the relation in the Cart model, additionally:

has_many :orders

After that you can simply add new orders to your current basket:

@order = Order.new
@order.cart = current_cart

EDIT:

Maybe there is an other Problem with the current_cart method.

Try:

@order.cart_id = session[:cart_id]