判断 mongoDB 是否连接

我的应用程序中有mongoDB.

在我听应用程序之前，我想判断mongoDB是否已连接.

这是最好的方式吗？

这是我的服务器.js文件:

var express = require('express');
var mongoDb = require('./mongoDb');
var app = express();

init();

function init() {
    if (mongoDb.isConnected()) {
      app.listen(8080, '127.0.0.1');
    }
    else {
      console.log('error');
    }
}

isConnected分getDbObject分.

然后，按连接的属性进行isConnected次解析/拒绝.

这是mongoDb.js文件:

//lets require/import the mongodb native drivers.
var mongodb = require('mongodb');
// Connection URL. This is where your mongodb server is running.
var url = 'mongodb://localhost:27017/myDb';

var connectingDb; // promise

//We need to work with "MongoClient" interface in order to connect to a mongodb server.
var MongoClient = mongodb.MongoClient;

init();

module.exports = {
    isConnected: isConnected
}

// Use connect method to connect to the Server
function init() {
  connectingDb = new Promise(
    function (resolve, reject) {
      MongoClient.connect(url, function (err, db) {
        if (err) {
          console.log('Unable to connect to the mongoDB server. Error:', err);
          reject(err);
        }
        else {
          console.log('Connection established to', url);

          //Close connection
          //db.close();
          resolve(db);
        }
      });

    }
  );
}

function getDbObject() {
  return connectingDb().then(myDb => {
                                       return {
                                          connected: true,
                                          db: myDb
                                        }
                                      }
                              )
                       .catch(err =>  {
                                        return {
                                          connected: false,
                                          db: err
                                        }
                                      }
                             )
}

function isConnected() {
    return new Promise(
        function(resolve, reject) {
          var obj = getDbObject();
          if (obj.connected == true) {
            console.log('success');
            resolve(true);
          }
          else {
            console.log('error');
            reject(false);
          }
        }
    )

}

感谢您的帮助！