如何通过 Promise 重用 mongodb 连接

问题描述

我想重用 MongoDB 连接.我知道 如何在 node.js 中重用 mongodb 连接我想使用 Promises 和 Mongo 驱动程序 v2 实现同样的目标

I want to reuse MongoDB connection. I 'am aware of How to reuse mongodb connection in node.js I want to acheive the same using Promises and Mongo driver v2

目前我必须为每个请求连接到数据库，这使得它变慢了.这是我的代码

Currently I have to connect to db for every request which makes it slow. This is my code

"use strict"
var app = require('./utils/express')();
var mongodb = require('mongodb');

var MongoClient = mongodb.MongoClient;
//Actually I 'am connecting to MongoLab
var url = 'mongodb://localhost/my-mongo';

app.set('port', (process.env.PORT || 5000));

app.listen(app.get('port'), function () {
  console.log('ParkMe app is running on port', app.get('port'));
});


app.get('/location/create', function(req,res,next){
  MongoClient.connect(url).then(function(db) {
    return db.collection('parkme_parkingLots').find({}).toArray().then(function (docs) {
      return docs;
    });
  });
});

我想做这样的事情:

"use strict"
var app = require('./utils/express')();
var mongodb = require('mongodb');

var MongoClient = mongodb.MongoClient;
var url = 'mongodb://nidhind:1234@ds051635.mongolab.com:51635/my-mongo';
var db = MongoClient.connect(url).then(function(db) {
    return db;
});

app.set('port', (process.env.PORT || 5000));

app.listen(app.get('port'), function () {
  console.log('ParkMe app is running on port', app.get('port'));
});


app.get('/location/create', function(req,res,next){
  db.collection('parkme_parkingLots').find({}).toArray().then(function (docs) {
    return docs;
  });
});

推荐答案

你快到了，你的代码只需要做几处更改:

You're almost there, there are only a couple of changes in your code to be made:

"use strict"
var app = require('./utils/express')();
var mongodb = require('mongodb');

var MongoClient = mongodb.MongoClient;
var url = 'mongodb://nidhind:1234@ds051635.mongolab.com:51635/my-mongo';
// no need to call then() yet
var connection = MongoClient.connect(url);

app.set('port', (process.env.PORT || 5000));

app.listen(app.get('port'), function() {
  console.log('ParkMe app is running on port', app.get('port'));
});


app.get('/location/create', function(req, res, next) {
  // the connection is opened once, use it at will
  connection.then(function(db) {
    db.collection('parkme_parkingLots').find({}).toArray().then(function(docs) {
      return docs;
    });
  });
});

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