Allow using saved cards at checkout

app/controllers/split_checkout_controller.rb

@@ -112,7 +112,7 @@ class SplitCheckoutController < ::BaseController
   end
 
   def order_params
-    @order_params ||= Checkout::Params.new(@order, params).call
+    @order_params ||= Checkout::Params.new(@order, params, spree_current_user).call
   end
 
   def redirect_to_step

app/services/checkout/params.rb

@@ -2,9 +2,10 @@
 
 module Checkout
   class Params
-    def initialize(order, params)
+    def initialize(order, params, current_user)
       @params = params
       @order = order
+      @current_user = current_user
     end
 
     def call
@@ -13,17 +14,18 @@ module Checkout
       apply_strong_parameters
       set_address_details
       set_payment_amount
+      set_existing_card
 
       @order_params
     end
 
     private
 
-    attr_reader :params, :order
+    attr_reader :params, :order, :current_user
 
     def apply_strong_parameters
       @order_params = params.require(:order).permit(
-        :email, :shipping_method_id, :special_instructions, :existing_card_id,
+        :email, :shipping_method_id, :special_instructions,
         :save_bill_address, :save_ship_address,
         bill_address_attributes: ::PermittedAttributes::Address.attributes,
         ship_address_attributes: ::PermittedAttributes::Address.attributes,
@@ -50,6 +52,22 @@ module Checkout
       @order_params[:payments_attributes].first[:amount] = order.total
     end
 
+    def set_existing_card
+      return unless existing_card_selected?
+
+      card = Spree::CreditCard.find(params[:existing_card_id])
+
+      if card.user_id.blank? || card.user_id != current_user&.id
+        raise Spree::Core::GatewayError, I18n.t(:invalid_credit_card)
+      end
+
+      @order_params[:payments_attributes].first[:source] = card
+    end
+
+    def existing_card_selected?
+      @order_params[:payments_attributes] && params[:existing_card_id].present?
+    end
+
     def addresses_present?
       @order_params[:ship_address_attributes] && @order_params[:bill_address_attributes]
     end

app/views/split_checkout/payment/_stripe_sca.html.haml

@@ -3,7 +3,7 @@
     .checkout-input
       %label
         = t('split_checkout.step2.form.stripe.use_saved_card')
-      = select_tag :existing_card,
+      = select_tag :existing_card_id,
         options_for_select(stripe_card_options(@saved_credit_cards) + [[t('split_checkout.step2.form.stripe.create_new_card'), ""]], @selected_card),
         { "data-action": "change->stripe-cards#onSelectCard", "data-stripe-cards-target": "select" }
 

spec/controllers/split_checkout_controller_spec.rb

@@ -141,6 +141,28 @@ describe SplitCheckoutController, type: :controller do
           expect(order.reload.state).to eq "confirmation"
         end
       end
+
+      context "with a saved credit card" do
+        let!(:saved_card) { create(:stored_credit_card, user: user) }
+        let(:checkout_params) do
+          {
+            order: {
+              payments_attributes: [
+                { payment_method_id: payment_method.id }
+              ]
+            },
+            existing_card_id: saved_card.id
+          }
+        end
+
+        it "updates and redirects to payment step" do
+          put :update, params: params
+
+          expect(response).to redirect_to checkout_step_path(:summary)
+          expect(order.reload.state).to eq "confirmation"
+          expect(order.payments.first.source.id).to eq saved_card.id
+        end
+      end
     end
 
     context "summary step" do