From 1d5a775dedff6d2e7817dcdac6305c6592cf099d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=B5=B5=E5=BF=A0=E6=9E=97?= <170083662@qq.com>
Date: Fri, 22 Aug 2025 17:50:55 +0800
Subject: [PATCH] =?UTF-8?q?fix(shop):=20=E4=BF=AE=E5=A4=8D=E4=BC=98?=
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- 增加了对优惠券不存在的检查
-安全地检查和更新优惠券的已领取数量，避免空指针异常
- 在 SQL 查询中使用 COALESCE 函数安全地获取已领取数量
---
 .../controller/ShopUserCouponController.java     | 16 ++++++++++++++--
 .../shop/mapper/xml/ShopCouponMapper.xml         |  3 ++-
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/main/java/com/gxwebsoft/shop/controller/ShopUserCouponController.java b/src/main/java/com/gxwebsoft/shop/controller/ShopUserCouponController.java
index 2c795f7..a9382b2 100644
--- a/src/main/java/com/gxwebsoft/shop/controller/ShopUserCouponController.java
+++ b/src/main/java/com/gxwebsoft/shop/controller/ShopUserCouponController.java
@@ -120,7 +120,15 @@ public class ShopUserCouponController extends BaseController {
       final User loginUser = getLoginUser();
       if (loginUser == null) return fail("请先登录");
       ShopCoupon coupon = couponService.getByIdRel(userCoupon.getCouponId());
-        if (coupon.getTotalCount() != -1 && coupon.getReceiveNum() >= coupon.getTotalCount()) return fail("已经被领完了");
+
+      // 检查优惠券是否存在
+      if (coupon == null) return fail("优惠券不存在");
+
+      // 安全地检查已领取数量，避免空指针异常
+      Integer receiveNum = coupon.getReceiveNum();
+      if (receiveNum == null) receiveNum = 0;
+
+      if (coupon.getTotalCount() != -1 && receiveNum >= coupon.getTotalCount()) return fail("已经被领完了");
         List<ShopUserCoupon> userCouponList = shopUserCouponService.list(
                 new LambdaQueryWrapper<ShopUserCoupon>()
                         .eq(ShopUserCoupon::getCouponId, userCoupon.getCouponId())
@@ -150,7 +158,11 @@ public class ShopUserCouponController extends BaseController {
         }
         userCoupon.setUserId(getLoginUserId());
         shopUserCouponService.save(userCoupon);
-        coupon.setReceiveNum(coupon.getReceiveNum() + 1);
+
+        // 安全地更新已领取数量，避免空指针异常
+        Integer currentReceiveNum = coupon.getReceiveNum();
+        if (currentReceiveNum == null) currentReceiveNum = 0;
+        coupon.setReceiveNum(currentReceiveNum + 1);
         couponService.updateById(coupon);
         return success("领取成功");
     }
diff --git a/src/main/java/com/gxwebsoft/shop/mapper/xml/ShopCouponMapper.xml b/src/main/java/com/gxwebsoft/shop/mapper/xml/ShopCouponMapper.xml
index b4fcda5..6030a91 100644
--- a/src/main/java/com/gxwebsoft/shop/mapper/xml/ShopCouponMapper.xml
+++ b/src/main/java/com/gxwebsoft/shop/mapper/xml/ShopCouponMapper.xml
@@ -4,7 +4,8 @@
 
     <!-- 关联查询sql -->
     <sql id="selectSql">
-        SELECT a.*
+        SELECT a.*,
+               COALESCE((SELECT COUNT(*) FROM shop_user_coupon suc WHERE suc.coupon_id = a.id AND suc.deleted = 0), 0) AS receive_num
         FROM shop_coupon a
         <where>
             <if test="param.id != null">