unknown attribute 'size' for OrderItem

Question

I'm getting the following error, unknown attribute 'size' for OrderItem. when I try to "checkout" with an item in a shopping cart that I created using Ruby on Rails. At first, the cart just managed the product_id and the quantity, but now I need to add a size attribute to products. I modified my class files to the following,

order_form.rb

class OrderForm
    include ActiveModel::Model

    attr_accessor :user, :order, :shipping_price # credit_card
    attr_writer :cart

    def save
        set_password_for_user

        if valid?
            persist
            true
        else
            false
        end
    end

    def has_errors?
        user.errors.any?
    end

    private

    def valid?
        user.valid?
    end

    def persist
    puts "inside persis shipping_price : #{shipping_price.inspect}"
        user.save
        @order = Order.create! user: user, shipping_price: shipping_price

        build_order_items
    end

    def set_password_for_user
        user.password = Digest::SHA1.hexdigest(user.email + Time.now.to_s)[0..8]
    end

    def build_order_items
        @cart.items.each do |item|
            @order.order_items.create! product_id: item.product_id, quantity: item.quantity, size: item.size
        end
    end
end

order_item.rb

class OrderItem < ActiveRecord::Base
  belongs_to :order
  belongs_to :product

  def total_price
    self.quantity * self.product.price
  end
end

cart_item.rb

class CartItem
    attr_reader :product_id, :quantity, :size

    def initialize product_id, quantity = 1, size
        @product_id = product_id
        @quantity = quantity
        @size = size
    end

    def increment
        @quantity = @quantity + 1
    end

    def product
        Product.find product_id
    end

    def total_price
        # puts "Hello cart_item"
        product.price * quantity
    end
end

cart.rb

class Cart
    attr_reader :items

    def self.build_from_hash hash
        items = if hash["cart"] then
            hash["cart"]["items"].map do |item_data|
                CartItem.new item_data["product_id"], item_data["quantity"], item_data["size"]
            end
        else
            []
        end

        new items
    end

    def initialize items = []
        @items = items
    end

    def add_item product_id, size
        item = @items.find { |item| item.product_id == product_id
                                    item.size == size }
        if item
            item.increment
        else
            @items << CartItem.new(product_id, size)
        end
    end

    def empty?
        @items.empty?
    end

    def count
        @items.length
    end

    def serialize
        items = @items.map do |item| 
            { 
                "product_id" => item.product_id, 
                "quantity" => item.quantity,
                "size" => item.size 
            } 
        end

        {
            "items" => items
        }
    end

    def total_price(shipping_price = 0)
        # puts "Hello cart"
        @items.inject(0) { |sum, item| sum + item.total_price } + shipping_price
    end
end

create_order_items.rb

class CreateOrderItems < ActiveRecord::Migration
  def change
    create_table :order_items do |t|
      t.references :order, index: true, foreign_key: true
      t.references :product, index: true, foreign_key: true
      t.integer :quantity

      t.timestamps null: false
    end
  end
end

Answer 1

it looks like you are calling .size on an OrderItems instance here:

 def build_order_items
        @cart.items.each do |item|
            @order.order_items.create! product_id: item.product_id, quantity: item.quantity, size: item.size
        end
    end

P.S. Please for the love of humanity start using parens.