app/controllers/spree/paypal_controller_decorator.rb

paypal_controller_decorator.rb

Spree::PaypalController.class_eval do

  def express
    order = current_order || raise(ActiveRecord::RecordNotFound)
    items = order.line_items.map(&method(:line_item))

    additional_adjustments = order.all_adjustments.additional
    tax_adjustments = additional_adjustments.tax
    shipping_adjustments = additional_adjustments.shipping

    additional_adjustments.eligible.each do |adjustment|
      next if (shipping_adjustments).include?(adjustment)
      items << {
        :Name => adjustment.label,
        :Quantity => 1,
        :Amount => {
          :currencyID => order.currency,
          :value => adjustment.amount
        }
      }
    end

    # Because PayPal doesn't accept $0 items at all.
    # See #10
    # https://cms.paypal.com/uk/cgi-bin/?cmd=_render-content&content_ID=developer/e_howto_api_ECCustomizing
    # "It can be a positive or negative value but not zero."
    items.reject! do |item|
      item[:Amount][:value].zero?
    end
    pp_request = provider.build_set_express_checkout(express_checkout_request_details(order, items))

    begin
      pp_response = provider.set_express_checkout(pp_request)
      if pp_response.success?
        redirect_to provider.express_checkout_url(pp_response, :useraction => 'commit')
      else
        flash[:error] = Spree.t('flash.generic_error', :scope => 'paypal', :reasons => pp_response.errors.map(&:long_message).join(" "))
        redirect_to checkout_state_path(:payment)
      end
    rescue SocketError
      flash[:error] = Spree.t('flash.connection_failed', :scope => 'paypal')
      redirect_to checkout_state_path(:payment)
    end
  end

  private

  def payment_details items
    # This retrieves the cost of shipping after promotions are applied
    # For example, if shippng costs $10, and is free with a promotion, shipment_sum is now $10
    shipment_sum = current_order.shipments.map(&:discounted_cost).sum

    # This calculates the item sum based upon what is in the order total, but not for shipping
    # or tax.  This is the easiest way to determine what the items should cost, as that
    # functionality doesn't currently exist in Spree core
    item_sum = current_order.total - shipment_sum

    if item_sum.zero?
      # Paypal does not support no items or a zero dollar ItemTotal
      # This results in the order summary being simply "Current purchase"
      {
        :OrderTotal => {
          :currencyID => current_order.currency,
          :value => current_order.total
        }
      }
    else
      {
        :OrderTotal => {
          :currencyID => current_order.currency,
          :value => current_order.total
        },
        :ItemTotal => {
          :currencyID => current_order.currency,
          :value => item_sum
        },
        :ShippingTotal => {
          :currencyID => current_order.currency,
          :value => shipment_sum,
        },
        :ShipToAddress => address_options,
        :PaymentDetailsItem => items,
        :ShippingMethod => "Shipping Method Name Goes Here",
        :PaymentAction => "Sale"
      }
    end
  end

end