[英]Using `mongoose transactions` when saving message in two collections in mongodb
如果學生向老師發送消息,則消息保存在teachers
students
中。 同樣的情況是當老師給學生發消息時,他們也被保存在兩個collections teachers
和students
中。 如何在以下代碼中應用mongoose transaction
,以便將消息保存在兩個 collections 中。我不希望消息將保存在一個集合中而另一個集合中由於錯誤而不會保存的情況。 我正在尋求幫助和線索
const express = require('express');
const mongoose = require('mongoose');
require('dotenv').config();
//const app = express();
// Connect to our Database and handle an bad connections
module.exports.db = mongoose
.createConnection(process.env.DATABASE, {
useNewUrlParser: true,
useFindAndModify: false,
useUnifiedTopology: true,
useCreateIndex: true
}
);
//controller
const db = require('./connection');
const session = db.startSession();
session.startTransaction();
module.exports.sendMessage = (req, res) => {
let {sender, receiver, msg, role} = req.body;
var hex = /[0-9A-Fa-f]{6}/g;
sender = (hex.test(sender))? mongoose.Types.ObjectId(sender) : sender;
receiver = (hex.test(receiver))? mongoose.Types.ObjectId(receiver) : receiver;
console.log(sender, receiver, msg, 'send');
if(role === 'tutor') {
let teacherMessage = new TeacherMessageSchema.TeacherMessageSchema({
contentInfo : {
msg : msg
},
sender : sender
})
let studentMessage = new TeacherMessageSchema.TeacherMessageSchema({
contentInfo : {
msg : msg
},
receiver : receiver
})
db.db.collection('teachers').findOneAndUpdate(
{ _id : receiver },
{ $push: { messages: teacherMessage } },
(err, updated) => {
console.log(updated, 'vvv');
updated.value.hashed_password = undefined;
updated.value.salt = undefined;
if(err) {
res.status(404).json(err);
}
if (updated) {
res.status(200).json(updated.value);
db.db.collection('students').findOneAndUpdate(
{ _id : sender },
{ $push: { messages: studentMessage } },
);
}
}, session(session)
)
}
if(role === 'student') {
let studentMessage = new StudentMessageSchema.StudentMessageSchema({
contentInfo : {
msg : msg
},
receiver : receiver
})
let teacherMessage = new TeacherMessageSchema.TeacherMessageSchema({
contentInfo : {
msg : msg
},
sender : sender
})
db.db.collection('students').findOneAndUpdate(
{ _id : sender },
{ $push: { messages: studentMessage } },
(err, updated) => {
console.log(updated, 'sss');
updated.value.hashed_password = undefined;
updated.value.salt = undefined;
if(err) {
res.status(404).json(err);
}
if (updated) {
res.json(updated.value);
db.db.collection('teachers').findOneAndUpdate(
{ _id : receiver },
{ $push: { messages: teacherMessage } },
)
}
},
), session(session)
}
}
記錄的變量 db
{
db: NativeConnection {
base: Mongoose {
connections: [Array],
models: [Object],
modelSchemas: [Object],
options: [Object],
_pluralize: [Function: pluralize],
plugins: [Array]
},
collections: {},
models: {},
config: { autoIndex: true },
replica: false,
options: null,
otherDbs: [],
relatedDbs: {},
states: [Object: null prototype] {
'0': 'disconnected',
'1': 'connected',
'2': 'connecting',
'3': 'disconnecting',
'99': 'uninitialized',
disconnected: 0,
connected: 1,
connecting: 2,
disconnecting: 3,
uninitialized: 99
},
_readyState: 1,
_closeCalled: false,
_hasOpened: true,
_listening: false,
_connectionOptions: {
useNewUrlParser: true,
useFindAndModify: false,
useUnifiedTopology: true,
useCreateIndex: true,
promiseLibrary: [Function: Promise]
},
client: MongoClient {
_events: [Object: null prototype] {},
_eventsCount: 0,
_maxListeners: undefined,
s: [Object],
topology: [ReplSet],
[Symbol(kCapture)]: false
},
name: null,
'$initialConnection': Promise { [Circular] },
db: Db {
_events: [Object: null prototype],
_eventsCount: 3,
_maxListeners: undefined,
s: [Object],
serverConfig: [Getter],
bufferMaxEntries: [Getter],
databaseName: [Getter],
[Symbol(kCapture)]: false
}
}
}
我在代碼中添加了任何時候出現錯誤:
等待 session.abortTransaction();
否則(快樂路徑)提交更改。
等待 session.commitTransaction();
Abort 和 commit 是 Promise 基本函數,所以我更改了它們用作異步的函數。
const express = require('express');
const mongoose = require('mongoose');
require('dotenv').config();
//const app = express();
// Connect to our Database and handle an bad connections
module.exports.db = mongoose
.createConnection(process.env.DATABASE, {
useNewUrlParser: true,
useFindAndModify: false,
useUnifiedTopology: true,
useCreateIndex: true
}
);
//controller
const db = require('./connection');
module.exports.sendMessage = async (req, res) => {
const session = await db.startSession();
session.startTransaction();
let {sender, receiver, msg, role} = req.body;
var hex = /[0-9A-Fa-f]{6}/g;
sender = (hex.test(sender))? mongoose.Types.ObjectId(sender) : sender;
receiver = (hex.test(receiver))? mongoose.Types.ObjectId(receiver) : receiver;
console.log(sender, receiver, msg, 'send');
if(role === 'tutor') {
let teacherMessage = new TeacherMessageSchema.TeacherMessageSchema({
contentInfo : {
msg : msg
},
sender : sender
})
let studentMessage = new TeacherMessageSchema.TeacherMessageSchema({
contentInfo : {
msg : msg
},
receiver : receiver
})
db.db.collection('teachers').findOneAndUpdate(
{ _id : receiver },
{ $push: { messages: teacherMessage } },
async (err, updated) => {
console.log(updated, 'vvv');
updated.value.hashed_password = undefined;
updated.value.salt = undefined;
if(err) {
await session.abortTransaction();
res.status(404).json(err);
return
}
if (updated) {
res.status(200).json(updated.value);
db.db.collection('students').findOneAndUpdate(
{ _id : sender },
{ $push: { messages: studentMessage } },
);
}
}, session(session)
)
}
if(role === 'student') {
let studentMessage = new StudentMessageSchema.StudentMessageSchema({
contentInfo : {
msg : msg
},
receiver : receiver
})
let teacherMessage = new TeacherMessageSchema.TeacherMessageSchema({
contentInfo : {
msg : msg
},
sender : sender
})
db.db.collection('students').findOneAndUpdate(
{ _id : sender },
{ $push: { messages: studentMessage } },
async (err, updated) => {
console.log(updated, 'sss');
updated.value.hashed_password = undefined;
updated.value.salt = undefined;
if(err) {
await session.abortTransaction();
res.status(404).json(err);
return;
}
if (updated) {
res.json(updated.value);
db.db.collection('teachers').findOneAndUpdate(
{ _id : receiver },
{ $push: { messages: teacherMessage } },
)
}
},
session(session)
)
}
await session.commitTransaction();
}
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