mongoose, how to record update_time in sub docs - node.js

Question

I have a mongoose schema is:
this is my mongoose schema
'use strict';
module.exports = app => {
const mongoose = app.mongoose;
const custSchema = new mongoose.Schema({
belong: { // 所属信息
user_id: { type: 'String', required: true },
type: { type: 'Number', required: true }, // bee、4s店、平台
username: { type: 'String', required: true }, // 用户名
},
delete: { type: Number, default: 0 },
info: { // 客户基本信息
name: { type: 'String', required: true }, // 客户姓名
brith: { type: 'Date', required: true }, // 出生日期
sex: { type: 'Number', required: true }, // 性别
eduction: Number, // 学历
level: { type: 'Number', required: true }, // 客户等级
tag: Number, // 客户标签
tel: { type: 'Number', required: true }, // 电话
family: { // 家庭信息
situation: Number, // 家庭类型
earning: Number, // 家庭总收入
location: { // 家庭住址
province: Number, // 省
city: Number, // 市县
region: Number, // 区镇
addr: String, // 具体地址
},
},
job: { // 工作信息
industry: Number, // 行业
company: String, // 公司
occupation: String, // 职位
earning: Number, // 收入
location: { // 公司地址
province: Number, // 省
city: Number, // 市县
region: Number, // 区镇
addr: String, // 具体地址
},
},
comment: String, // 备注
update_time: { type: 'Date', required: false }, // 数据更新时间
},
... other code
how to save update_time when I update a field in 'custSchema.info'?
such as: I want to update 'info.name', after that, a update_time in 'cust.schema.info' will be included.
I don't prefer to solve this question by add logic on Service, Can I solve it by defining schema?

Answer 1

Yes, you can! Actually, this is a common issue, there are several plugins to help you, my recommendation is: Mongoose Timestamp.
https://github.com/drudge/mongoose-timestamp
It is very simple, a single file, you can actually read it before integrating into you project directly on Github.
Then, you can use the timestamps as follows:
User.findOneAndUpdate({username: 'Prince'}, { password: 'goatcheese' }, { new: true, upsert: true })
.exec(function (err, updated) {
console.log(user.updatedAt); // Should be approximately createdAt + 1 second
console.log(user.createdAt < user.updatedAt); // true
});