我使用node-mongodb-native驱动与MongoDB写一个网站。

我有一些关于如何管理连接的问题:

Is it enough using only one MongoDB connection for all requests? Are there any performance issues? If not, can I setup a global connection to use in the whole application? If not, is it good if I open a new connection when request arrives, and close it when handled the request? Is it expensive to open and close a connection? Should I use a global connection pool? I hear the driver has a native connection pool. Is it a good choice? If I use a connection pool, how many connections should be used? Are there other things I should notice?


当前回答

使用下面的方法,您可以轻松地管理尽可能多的连接

var mongoose = require('mongoose');


//Set up default mongoose connection
const bankDB = ()=>{
    return  mongoose.createConnection('mongodb+srv://<username>:<passwprd>@mydemo.jk4nr.mongodb.net/<database>?retryWrites=true&w=majority',options);
    
}

bankDB().then(()=>console.log('Connected to mongoDB-Atlas bankApp...'))
       .catch((err)=>console.error('Could not connected to mongoDB',err));
       
//Set up second mongoose connection
const myDB = ()=>{
    return  mongoose.createConnection('mongodb+srv://<username>:<password>@mydemo.jk4nr.mongodb.net/<database>?retryWrites=true&w=majority',options);
   
}
myDB().then(()=>console.log('Connected to mongoDB-Atlas connection 2...'))
       .catch((err)=>console.error('Could not connected to mongoDB',err));

module.exports = { bankDB(), myDB() };

其他回答

下面是一些管理MongoDB连接的代码。

var MongoClient = require('mongodb').MongoClient;
var url = require("../config.json")["MongoDBURL"]

var option = {
  db:{
    numberOfRetries : 5
  },
  server: {
    auto_reconnect: true,
    poolSize : 40,
    socketOptions: {
        connectTimeoutMS: 500
    }
  },
  replSet: {},
  mongos: {}
};

function MongoPool(){}

var p_db;

function initPool(cb){
  MongoClient.connect(url, option, function(err, db) {
    if (err) throw err;

    p_db = db;
    if(cb && typeof(cb) == 'function')
        cb(p_db);
  });
  return MongoPool;
}

MongoPool.initPool = initPool;

function getInstance(cb){
  if(!p_db){
    initPool(cb)
  }
  else{
    if(cb && typeof(cb) == 'function')
      cb(p_db);
  }
}
MongoPool.getInstance = getInstance;

module.exports = MongoPool;

启动服务器时,调用initPool

require("mongo-pool").initPool();

然后在任何其他模块,你可以这样做:

var MongoPool = require("mongo-pool");
MongoPool.getInstance(function (db){
    // Query your MongoDB database.
});

这是基于MongoDB文档的。看一看。

npm i express mongoose

mongodb.js

const express = require('express');
const mongoose =require('mongoose')
const app = express();

mongoose.set('strictQuery', true);
mongoose.connect('mongodb://localhost:27017/db_name', {
    useNewUrlParser: true, 
    useUnifiedTopology: true
})
.then(() => console.log('MongoDB Connected...'))
.catch((err) => console.log(err))

app.listen(3000,()=>{ console.log("Started on port 3000 !!!") })
node mongodb.js

如果有人想在2021年用Typescript工作,这是我正在使用的:

import { MongoClient, Collection } from "mongodb";

const FILE_DB_HOST = process.env.FILE_DB_HOST as string;
const FILE_DB_DATABASE = process.env.FILE_DB_DATABASE as string;
const FILES_COLLECTION = process.env.FILES_COLLECTION as string;

if (!FILE_DB_HOST || !FILE_DB_DATABASE || !FILES_COLLECTION) {
  throw "Missing FILE_DB_HOST, FILE_DB_DATABASE, or FILES_COLLECTION environment variables.";
}

const client = new MongoClient(FILE_DB_HOST, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});

class Mongoose {
  static FilesCollection: Collection;

  static async init() {
    const connection = await client.connect();
    const FileDB = connection.db(FILE_DB_DATABASE);
    Mongoose.FilesCollection = FileDB.collection(FILES_COLLECTION);
  }
}


Mongoose.init();

export default Mongoose;

我相信如果请求发生得太快(在蒙古.init()有时间完成之前),将会抛出一个错误,因为Mongoose。FilesCollection将未定义。

import { Request, Response, NextFunction } from "express";
import Mongoose from "../../mongoose";

export default async function GetFile(req: Request, res: Response, next: NextFunction) {
  const files = Mongoose.FilesCollection;
  const file = await files.findOne({ fileName: "hello" });
  res.send(file);
}

例如,如果您调用文件。findOne({…})和猫鼬。FilesCollection未定义,那么您将得到一个错误。

您应该将连接创建为服务,然后在需要时重用它。

// db.service.js
import { MongoClient } from "mongodb";
import database from "../config/database";

const dbService = {
  db: undefined,
  connect: callback => {
    MongoClient.connect(database.uri, function(err, data) {
      if (err) {
        MongoClient.close();
        callback(err);
      }
      dbService.db = data;
      console.log("Connected to database");
      callback(null);
    });
  }
};

export default dbService;

我的App.js样本

// App Start
dbService.connect(err => {
  if (err) {
    console.log("Error: ", err);
    process.exit(1);
  }

  server.listen(config.port, () => {
    console.log(`Api runnning at ${config.port}`);
  });
});

想用就用吧

import dbService from "db.service.js"
const db = dbService.db

使用下面的方法,您可以轻松地管理尽可能多的连接

var mongoose = require('mongoose');


//Set up default mongoose connection
const bankDB = ()=>{
    return  mongoose.createConnection('mongodb+srv://<username>:<passwprd>@mydemo.jk4nr.mongodb.net/<database>?retryWrites=true&w=majority',options);
    
}

bankDB().then(()=>console.log('Connected to mongoDB-Atlas bankApp...'))
       .catch((err)=>console.error('Could not connected to mongoDB',err));
       
//Set up second mongoose connection
const myDB = ()=>{
    return  mongoose.createConnection('mongodb+srv://<username>:<password>@mydemo.jk4nr.mongodb.net/<database>?retryWrites=true&w=majority',options);
   
}
myDB().then(()=>console.log('Connected to mongoDB-Atlas connection 2...'))
       .catch((err)=>console.error('Could not connected to mongoDB',err));

module.exports = { bankDB(), myDB() };