feat: product number

services/product/internal/model/product_model.go

@@ -3,6 +3,8 @@ package model
 import (
 	"lone-services/pkg/modelbase"
 	"lone-services/services/product/internal/dao"
+
+	"gorm.io/gorm"
 )
 
 type ProductModel struct {
@@ -21,3 +23,19 @@ func (m ProductModel) Init() ProductModel {
 func (m ProductModel) Create(data *dao.ProductCreate) error {
 	return m.Base.Create(data)
 }
+
+// IncrNumber 原子增加库存
+func (m ProductModel) IncrNumber(id int64, n uint32) (int64, error) {
+	ret := modelbase.DB().Table(m.TableName()).
+		Where("id = ?", id).
+		Update("number", gorm.Expr("number + ?", n))
+	return ret.RowsAffected, ret.Error
+}
+
+// DecrNumber 原子减少库存（库存不足时 RowsAffected=0）
+func (m ProductModel) DecrNumber(id int64, n uint32) (int64, error) {
+	ret := modelbase.DB().Table(m.TableName()).
+		Where("id = ? AND number >= ?", id, n).
+		Update("number", gorm.Expr("number - ?", n))
+	return ret.RowsAffected, ret.Error
+}