后端：完成退款逻辑

order/order-service-api/src/main/java/cn/iocoder/mall/order/api/OrderReturnService.java

@@ -2,7 +2,6 @@ package cn.iocoder.mall.order.api;
 
 import cn.iocoder.common.framework.vo.CommonResult;
 import cn.iocoder.mall.order.api.dto.OrderReturnApplyDTO;
-import cn.iocoder.mall.order.api.dto.OrderReturnCreateDTO;
 
 /**
  * 订单退货
@@ -21,4 +20,16 @@ public interface OrderReturnService {
      */
     CommonResult orderReturnApply(OrderReturnApplyDTO orderReturnApplyDTO);
 
+    /**
+     * 更新退款成功
+     *
+     * 如果成功，则返回 success
+     * 如果失败，则返回具体原因
+     *
+     * @param orderId 订单编号
+     * @param refundPrice 退款金额
+     * @return 支付结果
+     */
+    String updateRefundSuccess(String orderId, Integer refundPrice);
+
 }

order/order-service-impl/src/main/java/cn/iocoder/mall/order/biz/service/OrderReturnServiceImpl.java

@@ -52,4 +52,9 @@ public class OrderReturnServiceImpl implements OrderReturnService {
         orderReturnMapper.insert(orderReturnDO);
         return CommonResult.success(null);
     }
+
+    @Override
+    public String updateRefundSuccess(String orderId, Integer refundPrice) {
+        return "success";
+    }
 }

order/order-service-impl/src/main/java/cn/iocoder/mall/order/biz/service/OrderServiceImpl.java

@@ -258,9 +258,11 @@ public class OrderServiceImpl implements OrderService {
         }
 
         // 标记优惠劵已使用
-        CommonResult<Boolean> useCouponCardResult = couponService.useCouponCard(userId, orderCreateDTO.getCouponCardId());
-        if (useCouponCardResult.isError()) {
-            return CommonResult.error(useCouponCardResult);
+        if (orderCreateDTO.getCouponCardId() != null) {
+            CommonResult<Boolean> useCouponCardResult = couponService.useCouponCard(userId, orderCreateDTO.getCouponCardId());
+            if (useCouponCardResult.isError()) {
+                return CommonResult.error(useCouponCardResult);
+            }
         }
 
         // TODO 芋艿，扣除库存