Question

I am getting this error

1 error(s) on assignment of multiparameter attributes

And I am pretty sure it is from the date_selector.

Here is my model

class Order < ActiveRecord::Base
  attr_accessor :card_type, :card_number, :card_verification, 
    :card_expires_on # I do not have these fields in my database
  attr_accessible :cart_id, :card_expires_on, :card_type, :first_name, 
    :ip_address, :last_name,:card_number, :card_verification, :zip, :address, 
    :state, :city

  def credit_card
    @credit_card ||= ActiveMerchant::Billing::CreditCard.new(
      :brand              => card_type,
      :number             => card_number,
      :verification_value => card_verification,
      :month              => card_expires_on.month,
      :year               => card_expires_on.year,
      :first_name         => first_name,
      :last_name          => last_name
      )
  end
end

And the part of the controller that is involved

def create
  @user = current_user
  @cart = current_cart
  @order = @cart.build_order(params[:order]) # here is where the error is
  @order.user_id = @user.id
  @order.ip_address = request.remote_ip
  ...
end

Here is the cart Model

class Cart < ActiveRecord::Base
  has_many :line_items, :dependent => :destroy
  has_one :order
  belongs_to :user

  def add_product(product_id)
    current_item = line_items.find_by_product_id(product_id)
    if current_item
      current_item.quantity += 1
    else
      current_item = line_items.build(:product_id => product_id)
    end
    current_item
  end

  def total_price
    line_items.to_a.sum { |item| item.total_price}
  end

  def total_price_in_cents
    return Integer(total_price * 100)
  end
end

And heres the order form that goes along with order.rb…Thank you again for the help!!!

<div class="field">
   <%= f.label :first_name %><br />
<%= f.text_field :first_name %>
</div>
<div class="field">
  <%= f.label :last_name %><br />
  <%= f.text_field :last_name %>
</div>
<div class="field">
  <%= f.label :address %>
  <%= f.text_field :address %>
</div>
<div class="field">
  <%= f.label :city %>
  <%= f.text_field :city %>
</div>
<div class="field">
  <%= f.label :state %>
  <%= f.select :state, @order.us_states %>
</div>
<div class="field">
  <%= f.label :zip %>
  <%= f.text_field :zip %>
</div>
<div class ="field">
  <%= f.label :card_type %> <br />
  <%= f.select :card_type, [["Visa", "visa"], ["MasterCard", "master"], ["Discover", "discover"], ["American Express", "american_express"]] %>
</div>
<div class="field">
  <%= f.label :card_number %><br />
  <%= f.text_field :card_number %>
</div>
<div class="field">ry
  <%= f.label :card_verification, "Card Verification (CVV)" %><br />
  <%= f.text_field :card_verification %>
</div>
<div class="field">
  <%= f.label :card_expires_on %><br />
  <%= f.date_select :card_expires_on, :discard_day => true, :start_year => Date.today.year, :end_year => (Date.today.year+10), :add_month_numbers => true %>
</div>
<div class="actions">
  <%= f.submit %>
</div>

Answer 1

Have you tried @order = @cart.orders.new(params[:order])?

In the case of a one-to-one relationship between an order and a cart, that would be:
@cart.order.new(params[:order])