```ruby
require 'card_reuse'

module Spree
  CheckoutController.class_eval do
    include CardReuse

    private

    def before_payment
      current_order.payments.destroy_all if request.put?
      @cards = all_cards_for_user(@order.user)
    end

    # we are overriding this method in order to substitue in the exisiting card information
    def object_params
      # For payment step, filter order parameters to produce the expected nested attributes for a single payment and its source, discarding attributes for payment methods other than the one selected
      if @order.payment?
        if params[:payment_source].present? && source_params = params.delete(:payment_source)[params[:order][:payments_attributes].first[:payment_method_id].underscore]
          if params[:existing_card]
            credit_card = Spree::CreditCard.find(params[:existing_card])
            authorize! :manage, credit_card
            params[:order][:payments_attributes].first[:source] = credit_card
          else
            params[:order][:payments_attributes].first[:source_attributes] = source_params
          end
        end
        if (params[:order][:payments_attributes])
          params[:order][:payments_attributes].first[:amount] = @order.total
        end
      end
      params[:order]
    end

  end
end
```

Put card setup stuff into its own before_filter instead of overriding
user
```ruby
require 'card_reuse'

module Spree
  CheckoutController.class_eval do
    include CardReuse

    before_filter :setup_cards

    private

    def setup_cards
      if @order.state == 'payment'
        current_order.payments.destroy_all if request.put?
        @cards = all_cards_for_user(@order.user)
      end
    end

    # we are overriding this method in order to substitue in the exisiting card information
    def object_params
      # For payment step, filter order parameters to produce the expected nested attributes for a single payment and its source, discarding attributes for payment methods other than the one selected
      if @order.payment?
        if params[:payment_source].present? && source_params = params.delete(:payment_source)[params[:order][:payments_attributes].first[:payment_method_id].underscore]
          if params[:existing_card]
            credit_card = Spree::CreditCard.find(params[:existing_card])
            authorize! :manage, credit_card
            params[:order][:payments_attributes].first[:source] = credit_card
          else
            params[:order][:payments_attributes].first[:source_attributes] = source_params
          end
        end
        if (params[:order][:payments_attributes])
          params[:order][:payments_attributes].first[:amount] = @order.total
        end
      end
      params[:order]
    end

  end
end
```
assistant