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：

GitHub - liuhongdi/digv16: gin框架中通过gorm使用事务

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，
网站：https://blog.imgtouch.com
原文: go语言web开发系列之十六:gin框架中通过gorm使用事务 – 架构森林

说明：作者:刘宏缔 邮箱: [email protected]

二，数据库及sql

1，数据表:

2,建表sql:

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

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

CREATE TABLE `m_order_goods` (
 `ogId` bigint unsigned NOT NULL AUTO_INCREMENT COMMENT 'id',
 `orderId` bigint unsigned NOT NULL COMMENT '订单id',
 `goodsId` bigint unsigned NOT NULL COMMENT '商品id',
 `buyNum` int unsigned NOT NULL COMMENT '购买数量',
 PRIMARY KEY (`ogId`),
 UNIQUE KEY `orderId_2` (`orderId`,`goodsId`)
) 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:

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

三，go代码说明

1,controller/orderController.go

package controller

import (
	"fmt"
	"github.com/gin-gonic/gin"
	"github.com/liuhongdi/digv16/global"
	"github.com/liuhongdi/digv16/service"
)

type OrderController struct{}

//result:= global.NewResult(c)

func NewOrderController() OrderController {
	return OrderController{}
}

//新加一个订单
func (o *OrderController) AddOne(c *gin.Context) {
	result := global.NewResult(c)

	goodsId:=1;
	buyNum:=11;

	orderOne,err := service.AddOneOrder(int64(goodsId),buyNum);
	if err != nil {
		result.Error(404,"数据处理错误")
	} else {
		result.Success(&orderOne);
	}
	return
}


//新加一个订单,使用tx
func (o *OrderController) AddOneTx(c *gin.Context) {
	result := global.NewResult(c)
	goodsId:=1;
	buyNum:=11;

	orderOne,err := service.AddOneOrderTx(int64(goodsId),buyNum);

	fmt.Println("orderOne:");
	fmt.Println(orderOne);
	fmt.Println(":end:");
	//if ()
	if (orderOne == nil || err != nil) {
		result.Error(20001,"数据处理错误")
	} else {
		result.Success(&orderOne);
	}
	return
}

2,service/order.go

package service

import (
	"github.com/liuhongdi/digv16/dao"
	"github.com/liuhongdi/digv16/model"
)

//新加一个订单
func AddOneOrder(goodsId int64,buyNum int) (*model.Order, error) {
	return dao.AddOneOrder(goodsId,buyNum)
}

//新加一个订单,使用tx
func AddOneOrderTx(goodsId int64,buyNum int) (*model.Order, error) {
	return dao.AddOneOrderTx(goodsId,buyNum)
}

3,dao/order.go

package dao

import (
	"errors"
	"fmt"
	"github.com/liuhongdi/digv16/global"
	"github.com/liuhongdi/digv16/model"
	"gorm.io/gorm"
)

//添加一个订单
func AddOneOrder(goodsId int64,buyNum int) (*model.Order, error) {
	//添加order
	order := model.Order{UserId: 1, SalePrice: "20.00"}
	resultCO := global.DBLink.Create(&order) // 通过数据的指针来创建
	if (resultCO.Error != nil) {
		return nil,resultCO.Error
	}
    //减库存
	result := global.DBLink.Debug().Table("m_goods").Where("goodsId = ? and stock >= ?", goodsId,buyNum).Update("stock", gorm.Expr("stock - ?", buyNum))
	if (result.Error != nil) {
		return nil,result.Error
	}
	if (result.RowsAffected <= 0){
		return nil,errors.New("减库存失败")
	}
    //添加订单商品
	orderId := order.OrderId;
	orderGoods := model.OrderGoods{OrderId:orderId,GoodsId:goodsId,BuyNum:buyNum}
	resultCOG := global.DBLink.Create(&orderGoods) // 通过数据的指针来创建
	if (resultCOG.Error != nil) {
		return nil,resultCOG.Error
	}
	//return
	return &order,nil
}


//添加一个订单
func AddOneOrderTx(goodsId int64,buyNum int) (*model.Order, error) {
	// 事务开始后，需要使用 tx 处理数据
	tx := global.DBLink.Begin()

	defer func() {
		if r := recover(); r != nil {
			fmt.Println("this is in defer recover")
			tx.Rollback()
		}
	}()

	if err := tx.Error; err != nil {
		return nil,err
	}

	//添加order
	order := model.Order{UserId: 1, SalePrice: "20.00"}
	resultCO := tx.Debug().Create(&order) // 通过数据的指针来创建
	if (resultCO.Error != nil) {
		tx.Rollback()
		return nil,resultCO.Error
	}

	/*
	var z int = 0
	var i int = 100 / z
	fmt.Println("i:%i",i)
    */
	//减库存
	result := tx.Debug().Table("m_goods").Where("goodsId = ? and stock >= ?", goodsId,buyNum).Update("stock", gorm.Expr("stock - ?", buyNum))
	if (result.Error != nil) {
		tx.Rollback()
		return nil,result.Error
	}
	if (result.RowsAffected <= 0){
		tx.Rollback()
		fmt.Println("减库存失败")
		return nil,errors.New("减库存失败")
	}
	//添加订单商品
	orderId := order.OrderId;
	orderGoods := model.OrderGoods{OrderId:orderId,GoodsId:goodsId,BuyNum:buyNum}
	resultCOG := tx.Debug().Create(&orderGoods) // 通过数据的指针来创建
	if (resultCOG.Error != nil) {
		tx.Rollback()
		return nil,resultCOG.Error
	}
    //commit
    fmt.Println("begin commit")
	errCM := tx.Commit().Error
	if (errCM != nil) {
		fmt.Println("begin return1")
		tx.Rollback()
		return nil,errCM
	}else {
		fmt.Println("begin return2")
		return &order,nil
	}
}

4,model/goods.go

package model

type Goods struct {
	GoodsId	int64  `gorm:"column:goodsId",json:"goodsId"` // 自增
	GoodsName	string  `gorm:"column:goodsName",json:"goodsName"`    // 用户id
	Stock int  `gorm:"column:stock",json:"stock"`  // 售价
}

func (Goods) TableName() string {
	return "m_goods"
}

5,model/order.go

package model

type Order struct {
	OrderId	int64  `gorm:"primaryKey;autoIncrement;column:orderId",json:"orderid"` // 自增
	UserId	int64  `gorm:"column:userId",json:"userid"`    // 用户id
	SalePrice string  `gorm:"column:salePrice",json:"saleprice"`  // 售价
}

func (Order) TableName() string {
	return "m_order"
}

6,router/router.go

package router

import (
	"github.com/gin-gonic/gin"
	"github.com/liuhongdi/digv16/controller"
	"github.com/liuhongdi/digv16/global"
	"log"
	"runtime/debug"
)

func Router() *gin.Engine {
	router := gin.Default()
	//处理异常
	router.NoRoute(HandleNotFound)
	router.NoMethod(HandleNotFound)
	router.Use(Recover)

	// 路径映射
	goodsc:=controller.NewGoodsController()
	router.GET("/goods/getone/:id", goodsc.GetOne);
	//router.GET("/article/list", articlec.GetList);

	orderc:=controller.NewOrderController()
	router.GET("/order/addone", orderc.AddOne);
	router.GET("/order/addonetx", orderc.AddOneTx);

	return router
}

func HandleNotFound(c *gin.Context) {
	global.NewResult(c).Error(404,"资源未找到")
	return
}

func Recover(c *gin.Context) {
	defer func() {
		if r := recover(); r != nil {
			//打印错误堆栈信息
			log.Printf("panic: %v\n", r)
			debug.PrintStack()
			global.NewResult(c).Error(500,"服务器内部错误")
		}
	}()
	//加载完 defer recover，继续后续接口调用
	c.Next()
}

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

	/*
	var z int = 0
	var i int = 100 / z
	fmt.Println("i:%i",i)
    */

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:

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

module github.com/liuhongdi/digv16

go 1.15

require (
	github.com/gin-gonic/gin v1.6.3
	github.com/jinzhu/gorm v1.9.16 // indirect
	gorm.io/driver/mysql v1.0.1
	gorm.io/gorm v1.20.6
)