新增事務

        let transaction; 

        try {
            transaction = await this.ctx.model.transaction();

            await this.ctx.model.Collect.create({id: 39, author: 'zyu111', count: 1}, {transaction})

            await this.ctx.model.Collect.create({id: 42, author: 'zyu8228', count: 1}, {transaction})

            await transaction.commit();

        } 
 
catch (err) {
            // console.log(err)
            console.log('回滾了。。。')
            await transaction.rollback();
        }

事務的操作物件 必須是 model