go语言web开发系列之十六:gin框架中通过gorm使用事务

一，演示项目的相关信息

1,地址：

https://github.com/liuhongdi/digv16

2，功能：以下订单为例，演示了在gorm中启用事务

3, 项目结构：如图:

说明：刘宏缔的go森林是一个专注golang的博客，
          地址：https://blog.csdn.net/weixin_43881017

说明：作者:刘宏缔 邮箱: 371125307@qq.com

二，数据库及sql

1，数据表:

2,建表sql:

1.  
   CREATE TABLE `m_goods` (
2.  
   `goodsId` bigint unsigned NOT NULL AUTO_INCREMENT COMMENT '商品id',
3.  
   `goodsName` varchar(200) NOT NULL DEFAULT '' COMMENT '商品名称',
4.  
   `stock` int unsigned NOT NULL DEFAULT '0' COMMENT '库存数量',
5.  
   PRIMARY KEY (`goodsId`)
6.  
   ) ENGINE=InnoDB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='商品表'

1.  
   CREATE TABLE `m_order` (
2.  
   `orderId` bigint unsigned NOT NULL AUTO_INCREMENT COMMENT '订单id',
3.  
   `userId` bigint unsigned NOT NULL DEFAULT '0' COMMENT '用户id',
4.  
   `salePrice` decimal(10,0) NOT NULL DEFAULT '0' COMMENT '订单金额',
5.  
   PRIMARY KEY (`orderId`),
6.  
   KEY `userId` (`userId`)
7.  
   ) ENGINE=InnoDB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='订单表'

1.  
   CREATE TABLE `m_order_goods` (
2.  
   `ogId` bigint unsigned NOT NULL AUTO_INCREMENT COMMENT 'id',
3.  
   `orderId` bigint unsigned NOT NULL COMMENT '订单id',
4.  
   `goodsId` bigint unsigned NOT NULL COMMENT '商品id',
5.  
   `buyNum` int unsigned NOT NULL COMMENT '购买数量',
6.  
   PRIMARY KEY (`ogId`),
7.  
   UNIQUE KEY `orderId_2` (`orderId`,`goodsId`)
8.  
   ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='订单商品表'

3,插入一条演示数据:

1.  
   INSERT INTO `m_goods` (`goodsId`, `goodsName`, `stock`) VALUES
2.  
   (1, '施丹兰蜂蜜牛奶手工皂', 10);

三，go代码说明

1,controller/orderController.go

1.  
   package controller
2.  
    
3.  
   import (
4.  
   "fmt"
5.  
   "github.com/gin-gonic/gin"
6.  
   "github.com/liuhongdi/digv16/global"
7.  
   "github.com/liuhongdi/digv16/service"
8.  
   )
9.  
    
10.  
    type OrderController struct{}
11.  
     
12.  
    //result:= global.NewResult(c)
13.  
     
14.  
    func NewOrderController() OrderController {
15.  
    return OrderController{}
16.  
    }
17.  
     
18.  
    //新加一个订单
19.  
    func (o *OrderController) AddOne(c *gin.Context) {
20.  
    result := global.NewResult(c)
21.  
     
22.  
    goodsId:=1;
23.  
    buyNum:=11;
24.  
     
25.  
    orderOne,err := service.AddOneOrder(int64(goodsId),buyNum);
26.  
    if err != nil {
27.  
    result.Error(404,"数据处理错误")
28.  
    } else {
29.  
    result.Success(&orderOne);
30.  
    }
31.  
    return
32.  
    }
33.  
     
34.  
     
35.  
    //新加一个订单,使用tx
36.  
    func (o *OrderController) AddOneTx(c *gin.Context) {
37.  
    result := global.NewResult(c)
38.  
    goodsId:=1;
39.  
    buyNum:=11;
40.  
     
41.  
    orderOne,err := service.AddOneOrderTx(int64(goodsId),buyNum);
42.  
     
43.  
    fmt.Println("orderOne:");
44.  
    fmt.Println(orderOne);
45.  
    fmt.Println(":end:");
46.  
    //if ()
47.  
    if (orderOne == nil || err != nil) {
48.  
    result.Error(20001,"数据处理错误")
49.  
    } else {
50.  
    result.Success(&orderOne);
51.  
    }
52.  
    return
53.  
    }

2,service/order.go

1.  
   package service
2.  
    
3.  
   import (
4.  
   "github.com/liuhongdi/digv16/dao"
5.  
   "github.com/liuhongdi/digv16/model"
6.  
   )
7.  
    
8.  
   //新加一个订单
9.  
   func AddOneOrder(goodsId int64,buyNum int) (*model.Order, error) {
10.  
    return dao.AddOneOrder(goodsId,buyNum)
11.  
    }
12.  
     
13.  
    //新加一个订单,使用tx
14.  
    func AddOneOrderTx(goodsId int64,buyNum int) (*model.Order, error) {
15.  
    return dao.AddOneOrderTx(goodsId,buyNum)
16.  
    }

3,dao/order.go

1.  
   package dao
2.  
    
3.  
   import (
4.  
   "errors"
5.  
   "fmt"
6.  
   "github.com/liuhongdi/digv16/global"
7.  
   "github.com/liuhongdi/digv16/model"
8.  
   "gorm.io/gorm"
9.  
   )
10.  
     
11.  
    //添加一个订单
12.  
    func AddOneOrder(goodsId int64,buyNum int) (*model.Order, error) {
13.  
    //添加order
14.  
    order := model.Order{UserId: 1, SalePrice: "20.00"}
15.  
    resultCO := global.DBLink.Create(&order) // 通过数据的指针来创建
16.  
    if (resultCO.Error != nil) {
17.  
    return nil,resultCO.Error
18.  
    }
19.  
    //减库存
20.  
    result := global.DBLink.Debug().Table("m_goods").Where("goodsId = ? and stock >= ?", goodsId,buyNum).Update("stock", gorm.Expr("stock - ?", buyNum))
21.  
    if (result.Error != nil) {
22.  
    return nil,result.Error
23.  
    }
24.  
    if (result.RowsAffected <= 0){
25.  
    return nil,errors.New("减库存失败")
26.  
    }
27.  
    //添加订单商品
28.  
    orderId := order.OrderId;
29.  
    orderGoods := model.OrderGoods{OrderId:orderId,GoodsId:goodsId,BuyNum:buyNum}
30.  
    resultCOG := global.DBLink.Create(&orderGoods) // 通过数据的指针来创建
31.  
    if (resultCOG.Error != nil) {
32.  
    return nil,resultCOG.Error
33.  
    }
34.  
    //return
35.  
    return &order,nil
36.  
    }
37.  
     
38.  
     
39.  
    //添加一个订单
40.  
    func AddOneOrderTx(goodsId int64,buyNum int) (*model.Order, error) {
41.  
    // 事务开始后，需要使用 tx 处理数据
42.  
    tx := global.DBLink.Begin()
43.  
     
44.  
    defer func() {
45.  
    if r := recover(); r != nil {
46.  
    fmt.Println("this is in defer recover")
47.  
    tx.Rollback()
48.  
    }
49.  
    }()
50.  
     
51.  
    if err := tx.Error; err != nil {
52.  
    return nil,err
53.  
    }
54.  
     
55.  
    //添加order
56.  
    order := model.Order{UserId: 1, SalePrice: "20.00"}
57.  
    resultCO := tx.Debug().Create(&order) // 通过数据的指针来创建
58.  
    if (resultCO.Error != nil) {
59.  
    tx.Rollback()
60.  
    return nil,resultCO.Error
61.  
    }
62.  
     
63.  
    /*
64.  
    var z int = 0
65.  
    var i int = 100 / z
66.  
    fmt.Println("i:%i",i)
67.  
    */
68.  
    //减库存
69.  
    result := tx.Debug().Table("m_goods").Where("goodsId = ? and stock >= ?", goodsId,buyNum).Update("stock", gorm.Expr("stock - ?", buyNum))
70.  
    if (result.Error != nil) {
71.  
    tx.Rollback()
72.  
    return nil,result.Error
73.  
    }
74.  
    if (result.RowsAffected <= 0){
75.  
    tx.Rollback()
76.  
    fmt.Println("减库存失败")
77.  
    return nil,errors.New("减库存失败")
78.  
    }
79.  
    //添加订单商品
80.  
    orderId := order.OrderId;
81.  
    orderGoods := model.OrderGoods{OrderId:orderId,GoodsId:goodsId,BuyNum:buyNum}
82.  
    resultCOG := tx.Debug().Create(&orderGoods) // 通过数据的指针来创建
83.  
    if (resultCOG.Error != nil) {
84.  
    tx.Rollback()
85.  
    return nil,resultCOG.Error
86.  
    }
87.  
    //commit
88.  
    fmt.Println("begin commit")
89.  
    errCM := tx.Commit().Error
90.  
    if (errCM != nil) {
91.  
    fmt.Println("begin return1")
92.  
    tx.Rollback()
93.  
    return nil,errCM
94.  
    }else {
95.  
    fmt.Println("begin return2")
96.  
    return &order,nil
97.  
    }
98.  
    }

4,model/goods.go

1.  
   package model
2.  
    
3.  
   type Goods struct {
4.  
   GoodsId int64 `gorm:"column:goodsId",json:"goodsId"` // 自增
5.  
   GoodsName string `gorm:"column:goodsName",json:"goodsName"` // 用户id
6.  
   Stock int `gorm:"column:stock",json:"stock"` // 售价
7.  
   }
8.  
    
9.  
   func (Goods) TableName() string {
10.  
    return "m_goods"
11.  
    }

5,model/order.go

1.  
   package model
2.  
    
3.  
   type Order struct {
4.  
   OrderId int64 `gorm:"primaryKey;autoIncrement;column:orderId",json:"orderid"` // 自增
5.  
   UserId int64 `gorm:"column:userId",json:"userid"` // 用户id
6.  
   SalePrice string `gorm:"column:salePrice",json:"saleprice"` // 售价
7.  
   }
8.  
    
9.  
   func (Order) TableName() string {
10.  
    return "m_order"
11.  
    }

6,router/router.go

1.  
   package router
2.  
    
3.  
   import (
4.  
   "github.com/gin-gonic/gin"
5.  
   "github.com/liuhongdi/digv16/controller"
6.  
   "github.com/liuhongdi/digv16/global"
7.  
   "log"
8.  
   "runtime/debug"
9.  
   )
10.  
     
11.  
    func Router() *gin.Engine {
12.  
    router := gin.Default()
13.  
    //处理异常
14.  
    router.NoRoute(HandleNotFound)
15.  
    router.NoMethod(HandleNotFound)
16.  
    router.Use(Recover)
17.  
     
18.  
    // 路径映射
19.  
    goodsc:=controller.NewGoodsController()
20.  
    router.GET("/goods/getone/:id", goodsc.GetOne);
21.  
    //router.GET("/article/list", articlec.GetList);
22.  
     
23.  
    orderc:=controller.NewOrderController()
24.  
    router.GET("/order/addone", orderc.AddOne);
25.  
    router.GET("/order/addonetx", orderc.AddOneTx);
26.  
     
27.  
    return router
28.  
    }
29.  
     
30.  
    func HandleNotFound(c *gin.Context) {
31.  
    global.NewResult(c).Error(404,"资源未找到")
32.  
    return
33.  
    }
34.  
     
35.  
    func Recover(c *gin.Context) {
36.  
    defer func() {
37.  
    if r := recover(); r != nil {
38.  
    //打印错误堆栈信息
39.  
    log.Printf("panic: %v ", r)
40.  
    debug.PrintStack()
41.  
    global.NewResult(c).Error(500,"服务器内部错误")
42.  
    }
43.  
    }()
44.  
    //加载完 defer recover，继续后续接口调用
45.  
    c.Next()
46.  
    }

7,其他相关代码可访问github查看

四，测试效果

1,测试除0错:

访问:

http://127.0.0.1:8080/order/addonetx

   返回:

2,测试扣减库存出错

把dao/order.go中，

AddOneOrderTx方法中的除0错代码注释掉

1.  
   /*
2.  
   var z int = 0
3.  
   var i int = 100 / z
4.  
   fmt.Println("i:%i",i)
5.  
   */

再次执行:访问:

http://127.0.0.1:8080/order/addonetx

可以从控制台看到输出的提示:

1.  
   2021/01/13 13:32:25 /data/liuhongdi/digv16/dao/order.go:69
2.  
   [2.219ms] [rows:0] UPDATE `m_goods` SET `stock`=stock - 11 WHERE goodsId = 1 and stock >= 11
3.  
   减库存失败

3，测试正常执行事务成功

把controller/orderController.go中，

AddOneTx方法，把buyNum的值改为9

buyNum:=9

再次执行:

http://127.0.0.1:8080/order/addonetx

返回:

事务执行已成功

五，使用的库的版本:

1.  
   module github.com/liuhongdi/digv16
2.  
    
3.  
   go 1.15
4.  
    
5.  
   require (
6.  
   github.com/gin-gonic/gin v1.6.3
7.  
   github.com/jinzhu/gorm v1.9.16 // indirect
8.  
   gorm.io/driver/mysql v1.0.1
9.  
   gorm.io/gorm v1.20.6
10.  
    )