elf-shop/service/order_service.go

package service

import (
	e "errors"
	"gold-shop/errors"
	"gold-shop/global"
	"gold-shop/model"
	"gold-shop/request"
	"gold-shop/utils"
	"gorm.io/gorm"
)

var OrderService = orderService{}

type orderService struct {
}

func (orderService) Order(orderRequest request.OrderRequest, user *model.User) (*model.Order, error) {
	product := &model.Product{}
	err := global.DB.Where("id", orderRequest.ProductID).First(product).Error
	if e.Is(err, gorm.ErrRecordNotFound) {
		return nil, errors.NewBusinessError("商品不存在")
	}
	totalAmount := float64(orderRequest.Num) * product.Price
	if user.Balance < totalAmount {
		return nil, errors.NewBusinessError("账号余额不足")
	}

	orderNo := utils.GenerateNo("order")

	tx := global.DB.Begin()
	order := model.Order{}
	order.OrderNo = orderNo
	order.Amount = totalAmount
	order.UserID = user.ID
	err = global.DB.Save(&order).Error
	if err != nil {
		tx.Rollback()
		return nil, errors.NewBusinessError("保存数据失败")
	}

	orderProduct := model.OrderProduct{}
	orderProduct.ProductID = orderRequest.ProductID
	orderProduct.OrderNo = orderNo
	orderProduct.Price = product.Price
	orderProduct.Amount = totalAmount
	orderProduct.Num = orderRequest.Num
	err = global.DB.Save(&orderProduct).Error
	if err != nil {
		tx.Rollback()
		return nil, errors.NewBusinessError("保存数据失败")
	}

	global.DB.Model(user).Update("balance", gorm.Expr("balance - ?", totalAmount))
	tx.Commit()

	return &order, nil
}

func (orderService) GetOrders(userID, page, pageSize int) ([]model.Order, int64) {
	orders := make([]model.Order, pageSize)
	offset := (page - 1) * pageSize
	var total int64
	global.DB.Where("user_id", userID).Preload("OrderProducts").Offset(offset).Limit(pageSize).Find(&orders)
	global.DB.Model(&model.Order{}).Where("user_id", userID).Count(&total)
	return orders, total
}