Rails missing parameters id=> nil

Question

In my ruby on rails application i've got a partial called _cart.html.erb

<h2>Your Cart</h2>
<table>

  <%= render(cart.line_items) %>

  <tr class="total_line">
    <td colspan="2">Total</td>
    <td class="total_cell"><%= number_to_currency(cart.total_price) %></td>
  </tr>

</table>

<%= button_to 'Checkout', new_order_path, method: :get %>
<%= button_to 'Empty cart', cart, method: :delete,
    data: { confirm: 'Are you sure?' } %>

if a cart have one or more line_items i can place an order, in the carts controller I check if the cart have some line_items:

class OrdersController < ApplicationController
  include CurrentCart
  before_action :set_cart, only: [:new, :create]
  before_action :set_order, only: [:show, :edit, :update, :destroy]

  # GET /orders/new

  def new
    if @cart.line_items.empty?
      redirect_to store_url, notice: "Your cart is empty"
      return
    end

    @order = Order.new
  end
  # POST /orders
  # POST /orders.json
  def create
    @order = Order.new(order_params) 
    @order.add_line_items_from_cart(@cart)

    respond_to do |format|
      if @order.save
        format.html { redirect_to @order, notice: 'Order was successfully created.' }
        format.json { render :show, status: :created, location: @order }
      else
        format.html { render :new }
        format.json { render json: @order.errors, status: :unprocessable_entity }
      end
    end
  end
end

where the module CurrentCart is

module CurrentCart
  extend ActiveSupport::Concern

  private

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

and the model Order is:

class Order < ActiveRecord::Base
    has_many :line_items, dependent: :destroy

    PAYMENT_TYPES = ["Check", "Credit Card", "Purchase order"]

    validates :name, :address, :email, presence: true
    validates :pay_type, inclusion: PAYMENT_TYPES

    def add_line_items_from_cart(cart)
        cart.line_items.each do |item|
            item.cart.id = nil
            line_items << item
        end
    end
end

during the validation if i set all the Order's fields blank i recive this error (this output is from the server's console log):

ActionView::Template::Error (No route matches {:action=>"show", :controller=>"carts", :id=>nil} missing required keys: [:id]):
11: </table>
12: 
13: <%= button_to 'Checkout', new_order_path, method: :get %>
14: <%= button_to 'Empty cart', cart, method: :delete,
15:     data: { confirm: 'Are you sure?' } %>

it seems i miss the parameter :id during the validation. the web output highlight the <%= button_to 'Empty cart', cart, method: :delete, data: { confirm: 'Are you sure' } %> string.

i don't know why the application lose this parameter. All the help and tips will be appreciated.

Answer 1

It seems like you need params cart_id in your show page. You have to add in your before_filter

before_action :set_cart, only: [:show, :new, :create]