fix(core): 修复 BigDecimal 字段反序列化 null 值问题

- 新增 BigDecimalDeserializer 自定义反序列化器，处理 null值和空字符串
- 添加 DatabaseFixController 控制器，用于检查和修复数据库中的 null值问题
- 修改 ShopUserCouponController 中的查询逻辑，确保 BigDecimal 字段不为 null
- 更新 ShopCoupon 和 ShopUserCoupon 实体类，为 BigDecimal 字段添加 JsonSerialize 和 JsonInclude 注解
- 新增 SQL 脚本 fix_bigdecimal_null_values.sql，用于修复数据库中的 null 值问题- 修改 application.yml，配置 Jackson序列化和反序列化相关参数

src/main/resources/sql/fix_bigdecimal_null_values.sql

@@ -0,0 +1,107 @@
+-- 修复BigDecimal字段的null值问题
+-- 将null值替换为0.00，避免JSON序列化异常
+
+-- ========================================
+-- 1. 修复用户优惠券表的null值
+-- ========================================
+
+-- 检查当前null值情况
+SELECT 
+    'shop_user_coupon null值检查' as table_name,
+    COUNT(*) as total_records,
+    COUNT(CASE WHEN reduce_price IS NULL THEN 1 END) as null_reduce_price,
+    COUNT(CASE WHEN min_price IS NULL THEN 1 END) as null_min_price
+FROM shop_user_coupon;
+
+-- 修复reduce_price字段的null值
+UPDATE shop_user_coupon 
+SET reduce_price = 0.00 
+WHERE reduce_price IS NULL;
+
+-- 修复min_price字段的null值
+UPDATE shop_user_coupon 
+SET min_price = 0.00 
+WHERE min_price IS NULL;
+
+-- ========================================
+-- 2. 修复优惠券模板表的null值
+-- ========================================
+
+-- 检查当前null值情况
+SELECT 
+    'shop_coupon null值检查' as table_name,
+    COUNT(*) as total_records,
+    COUNT(CASE WHEN reduce_price IS NULL THEN 1 END) as null_reduce_price,
+    COUNT(CASE WHEN min_price IS NULL THEN 1 END) as null_min_price
+FROM shop_coupon;
+
+-- 修复reduce_price字段的null值
+UPDATE shop_coupon 
+SET reduce_price = 0.00 
+WHERE reduce_price IS NULL;
+
+-- 修复min_price字段的null值
+UPDATE shop_coupon 
+SET min_price = 0.00 
+WHERE min_price IS NULL;
+
+-- ========================================
+-- 3. 设置字段默认值（可选）
+-- ========================================
+
+-- 为用户优惠券表字段设置默认值
+ALTER TABLE shop_user_coupon 
+MODIFY COLUMN reduce_price DECIMAL(10,2) DEFAULT 0.00 COMMENT '满减券-减免金额';
+
+ALTER TABLE shop_user_coupon 
+MODIFY COLUMN min_price DECIMAL(10,2) DEFAULT 0.00 COMMENT '最低消费金额';
+
+-- 为优惠券模板表字段设置默认值
+ALTER TABLE shop_coupon 
+MODIFY COLUMN reduce_price DECIMAL(10,2) DEFAULT 0.00 COMMENT '满减券-减免金额';
+
+ALTER TABLE shop_coupon 
+MODIFY COLUMN min_price DECIMAL(10,2) DEFAULT 0.00 COMMENT '最低消费金额';
+
+-- ========================================
+-- 4. 验证修复结果
+-- ========================================
+
+-- 检查修复后的情况
+SELECT 
+    'shop_user_coupon 修复后检查' as table_name,
+    COUNT(*) as total_records,
+    COUNT(CASE WHEN reduce_price IS NULL THEN 1 END) as null_reduce_price,
+    COUNT(CASE WHEN min_price IS NULL THEN 1 END) as null_min_price,
+    MIN(reduce_price) as min_reduce_price,
+    MIN(min_price) as min_min_price
+FROM shop_user_coupon;
+
+SELECT 
+    'shop_coupon 修复后检查' as table_name,
+    COUNT(*) as total_records,
+    COUNT(CASE WHEN reduce_price IS NULL THEN 1 END) as null_reduce_price,
+    COUNT(CASE WHEN min_price IS NULL THEN 1 END) as null_min_price,
+    MIN(reduce_price) as min_reduce_price,
+    MIN(min_price) as min_min_price
+FROM shop_coupon;
+
+-- ========================================
+-- 5. 检查其他可能的BigDecimal字段
+-- ========================================
+
+-- 检查订单相关表的BigDecimal字段
+SELECT 
+    'shop_order BigDecimal字段检查' as check_type,
+    COUNT(*) as total_records,
+    COUNT(CASE WHEN order_price IS NULL THEN 1 END) as null_order_price,
+    COUNT(CASE WHEN pay_price IS NULL THEN 1 END) as null_pay_price
+FROM shop_order;
+
+-- 如果发现null值，可以执行以下修复
+/*
+UPDATE shop_order SET order_price = 0.00 WHERE order_price IS NULL;
+UPDATE shop_order SET pay_price = 0.00 WHERE pay_price IS NULL;
+*/
+
+SELECT 'BigDecimal null值修复完成！' as result;