Coupon_error_extension.rb

	CheckoutsController.class_eval do
	
	  # customized verison of the standard r_c update method (since we need to handle gateway errors, etc)
	  def update      
	    load_object
	
	    # call the edit hooks for the current step in case we experience validation failure and need to edit again
	    edit_hooks
	    @checkout.enable_validation_group(@checkout.state.to_sym)
	    @prev_state = @checkout.state
	    
	    before :update
	
	    begin
	      if object.update_attributes object_params
	        update_hooks
	        @order.update_totals!
	        after :update
	        next_step
	        if @checkout.completed_at
	          return complete_checkout
	        end
	      else
	        after :update_fails
	        set_flash :update_fails
	     end
	    rescue Spree::GatewayError => ge
	      logger.debug("#{ge}:\n#{ge.backtrace.join("\n")}")
	      flash.now[:error] = t("unable_to_authorize_credit_card") + ": #{ge.message}"
	    end
	    
	    # -- Set error flash if coupon code was provided but invalid
	    if params[:checkout] and params[:checkout][:coupon_code]
		coupon = Coupon.find_by_code(params[:checkout][:coupon_code].upcase)
		flash.now[:error] = t("invalid_coupon_code") unless coupon
	    end 
	    # -- end coupon check	
	    render 'edit'
	  end
	end