如何在 node.js 中重用 mongodb 连接

Question

我正在使用node-mongodb-native驱动和mongodb来写一个网站。

我有一个关于如何打开一次mongodb连接的问题，然后在user.js的集合名称用户和comment.js的集合名称帖子中使用它

我想在db.js 中打开数据库连接，然后为用户和帖子集合插入/保存数据

目前正在编码，我的db.js

var Db = require('mongodb').Db,
    Connection = require('mongodb').Connection,
    Server = require('mongodb').Server;
module.exports = new Db(
    'blog', 
    new Server('localhost', Connection.DEFAULT_PORT, {auto_reconnect: true})
);

我在user.js中使用db.js如下

var mongodb = require('./db');

function User(user){
  this.name = user.name;
  this.password = user.password;
  this.email = user.email;
};

module.exports = User;

User.prototype.save = function(callback) {//save user information
  //document to save in db
  var user = {
      name: this.name,
      password: this.password,
      email: this.email
  };
  mongodb.close();
  //open mongodb database
  mongodb.open(function(err, db){
    if(err){
      return callback(err);
    }
    //read users collection
    db.collection('users', function(err, collection){
      if(err){
        mongodb.close();
        return callback(err);
      }
      //insert data into users collections
      collection.insert(user,{safe: true}, function(err, user){
        mongodb.close();
        callback(err, user);//success return inserted user information
      });
    });
  });
};

和comment.js

var mongodb = require('./db');

function Comment(name, day, title, comment) {
  this.name = name;
  this.day = day;
  this.title = title;
  this.comment = comment;
}

module.exports = Comment;

Comment.prototype.save = function(callback) {
  var name = this.name,
      day = this.day,
      title = this.title,
      comment = this.comment;
  mongodb.open(function (err, db) {
    if (err) {
      return callback(err);
    }
    db.collection('posts', function (err, collection) {
      if (err) {
        mongodb.close();
        return callback(err);
      }
      //depend on name time and title add comment
      collection.findAndModify({"name":name,"time.day":day,"title":title}
      , [ ['time',-1] ]
      , {$push:{"comments":comment}}
      , {new: true}
      , function (err,comment) {
          mongodb.close();
          callback(null);
      });   
    });
  });
};

Answer 1

您可以连接一次，然后根据需要多次重复使用它：

var mongodb = require('mongodb');
var events = require('events');
var event = new events.EventEmitter();
var access = new mongodb.Server(host, port, { });
var client = null;

new mongodb.Db('YOUR DATABASE', access, { safe: true, auto_reconnect: true }).open(function (err, c) {
  if (!err) {
    client = c;
    console.log('database connected');
    event.emit('connect');
  } else {
    console.log('database connection error', err);
    event.emit('error');
  }
});

exports.get = function(fn) {
  if(client) {
    fn(client);
  } else {
    event.on('connect', function() {
      fn(client);
    });
  }
};

然后重复使用它：

var db = require('./db');
var items;
db.get(function(client) {
  items = new mongodb.Collection(client, 'collection');
});

// then anywhere in your code
db.get(function() {
  // items.find({ ...
});

Answer 2

接受的答案是 3 岁，它不适用于最新的 node-mongodb-native 驱动程序。我修改了@moka 的答案并添加了一些延迟和重试逻辑。

var MongoClient = require('mongodb').MongoClient;
var events = require('events');
var event = new events.EventEmitter();
var database = null;
var retries = 0;
var delay = 300;

setTimeout(connect,delay);

// Use connect method to connect to the server
function connect(){
    MongoClient.connect(process.env.MONGODB_URL, function(err, db) {
        if(!err){
            console.log("Connected successfully to server");
            database = db;
            event.emit('dbconnect');

        } else {
            if(retries < 4){
                console.log('Retrying to connect db %s', retries++);
                setTimeout(connect,delay);
            } else {
                console.log('Unable to connect db');
            }
        }
    });
}


exports.get = function(fn) {
    if(database !== null) {
        fn(database);
    } else {
        event.on('dbconnect', function() {
            fn(database);
        });
    }
};