Question

我正在使用node，mysql和angular4开发一个应用程序。在那里，我有一组与单个任务相关的功能。所有这些都是异步函数，适用于看起来像这样的承诺

setAprroveTrue(curentHOD, user, group, message, approvemail, approved_byHR = 0) { //HR or super admin can override anyones leave. default it is set as not by and hr.
        return new Promise((resolve, reject) => {
            Leaves.setHodMessage(group, message, curentHOD).then((messageArr) => {
                q = "update leave_taken_superior_map set lstm_col_status= ? ,ltsm_all_approved = 1,ltsm_overide_by_hr = ?,ltsm_message = ? where ltsm_group_id = ?;update leave_taken set alt_leave_approved = 1 where alt_group_by = ?";
                params = [config.key_word_approved_leave, approved_byHR, messageArr, group, group];
                sqlq.executeQuery(q, params).then((data) => {
                    if (approvemail === true) {
                        emails.sendEmail('pavithrarox1@gmail.com', 'pavithra@gmail.lk', 'Good news! Your leave request has been approved', emails.getLeaveApprovedEmail(group))
                    } else {
                        emails.sendEmail('pavithrarox1@gmail.com', 'pavithra@gmail.lk', 'Bad news! Your leave request has been rejected', emails.getLeaveDissapprovedEmail(group))
                    }
                    //no need to wait for email to send.it will work as a background procass
                    resolve(data)
                }).catch((err) => {
                    console.log(err)
                    reject(err)
                });
            }).catch((err) => {
                reject(err)
            })
        })
    }

如何在此功能中实现交易？因此，如果setHodMessage函数成功执行，并且executeQuery函数出现问题。我如何回滚一切？

Answer 1

您可以处理拒绝案例并同样应用逻辑。

所以每个承诺都有解决和拒绝以及阻止阻止

promise.then(
      resolved=>{},
      reject=>{}
).catch(error=>{});

所以在你的情况下。

setAprroveTrue(curentHOD, user, group, message, approvemail, approved_byHR = 0) { //HR or super admin can override anyones leave. default it is set as not by and hr.
        return new Promise((resolve, reject) => {
            Leaves.setHodMessage(group, message, curentHOD).then((messageArr) => {
                q = "update leave_taken_superior_map set lstm_col_status= ? ,ltsm_all_approved = 1,ltsm_overide_by_hr = ?,ltsm_message = ? where ltsm_group_id = ?;update leave_taken set alt_leave_approved = 1 where alt_group_by = ?";
                params = [config.key_word_approved_leave, approved_byHR, messageArr, group, group];
                sqlq.executeQuery(q, params).then((data) => {
                    if (approvemail === true) {
                        emails.sendEmail('pavithrarox1@gmail.com', 'pavithra@gmail.lk', 'Good news! Your leave request has been approved', emails.getLeaveApprovedEmail(group))
                    } else {
                        emails.sendEmail('pavithrarox1@gmail.com', 'pavithra@gmail.lk', 'Bad news! Your leave request has been rejected', emails.getLeaveDissapprovedEmail(group))
                    }
                    //no need to wait for email to send.it will work as a background procass
                    resolve(data)
                },()=>{  
                        //do your rollback stuff here
                      }).catch((err) => {
                    console.log(err)
                    reject(err)
                });
            }).catch((err) => {
                reject(err)
            })
        })
    }

Lemme知道您是否需要任何帮助。

Answer 2

好的，我在这里找到了问题。我无法使事务在我的应用程序上运行的原因是因为我使用了mysql.createPool而不是mysql.createConnection。没有选项可以在createPool中实现事务

如何使用节点promises实现事务

2 个答案: