在 NodeJs 中处理 Mongodb 全局连接的最佳方法是什么 [英] What is best way to handle global connection of Mongodb in NodeJs

问题描述

我使用 Node-Mongo-Native 并尝试设置全局连接变量，但我对两种可能的解决方案感到困惑.你们能帮我找出哪一个是好的吗?1. 解决方案(这很糟糕，因为每个请求都会尝试创建一个新连接.)

I using Node-Mongo-Native and trying to set a global connection variable, but I am confused between two possible solutions. Can you guys help me out with which one would be the good one? 1. Solution ( which is bad because every request will try to create a new connection.)

var express = require('express');  
var app = express();  
var MongoClient = require('mongodb').MongoClient;  
var assert = require('assert');

// Connection URL
var url = '[connectionString]]';

// start server on port 3000
app.listen(3000, '0.0.0.0', function() {  
  // print a message when the server starts listening
  console.log("server starting");
});

// Use connect method to connect to the server when the page is requested
app.get('/', function(request, response) {  
  MongoClient.connect(url, function(err, db) {
    assert.equal(null, err);
    db.listCollections({}).toArray(function(err, collections) {
        assert.equal(null, err);
        collections.forEach(function(collection) {
            console.log(collection);
        });
        db.close();
    })
    response.send('Connected - see console for a list of available collections');
  });
});

1. 解决方案(在应用程序初始化时连接并将连接字符串分配给全局变量).但我认为将连接字符串分配给全局变量不是一个好主意.

1. Solution ( to connect at app init and assign the connection string to a global variable). but I believe assigning connection string to a global variable is a not a good idea.

var mongodb;var url = '[connectionString]';MongoClient.connect(url, function(err, db) {
assert.equal(null, err);mongodb=db;});

var mongodb; var url = '[connectionString]'; MongoClient.connect(url, function(err, db) {
assert.equal(null, err); mongodb=db; } );

我想在应用初始化时创建一个连接并在整个应用生命周期中使用.

I want to create a connection at the app initialization and use throughout the app lifetime.

你们能帮帮我吗?谢谢.

Can you guys help me out? Thanks.

推荐答案

创建一个 Connection 单例模块来管理应用程序数据库连接.

Create a Connection singleton module to manage the apps database connection.

MongoClient 不提供单例连接池，因此您不想在应用中重复调用 MongoClient.connect().用于包装 mongo 客户端的单例类适用于我见过的大多数应用.

MongoClient does not provide a singleton connection pool so you don't want to call MongoClient.connect() repeatedly in your app. A singleton class to wrap the mongo client works for most apps I've seen.

const MongoClient = require('mongodb').MongoClient

class Connection {

    static async open() {
        if (this.db) return this.db
        this.db = await MongoClient.connect(this.url, this.options)
        return this.db
    }

}

Connection.db = null
Connection.url = 'mongodb://127.0.0.1:27017/test_db'
Connection.options = {
    bufferMaxEntries:   0,
    reconnectTries:     5000,
    useNewUrlParser:    true,
    useUnifiedTopology: true,
}

module.exports = { Connection }

在您require('./Connection') 的任何地方，Connection.open() 方法都可用，Connection.db 方法也可用code> 属性(如果已初始化).

Everywhere you require('./Connection'), the Connection.open() method will be available, as will the Connection.db property if it has been initialised.

const router = require('express').Router()
const { Connection } = require('../lib/Connection.js')

// This should go in the app/server setup, and waited for.
Connection.open()

router.get('/files', async (req, res) => {
   try {
     const files = await Connection.db.collection('files').find({})
     res.json({ files })
   }
   catch (error) {
     res.status(500).json({ error })
   }
})

module.exports = router

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