How can I use async-await with MongoClient

问题

When I run this (using node v7.5.0 with --harmony):

var MongoClient = require('mongodb').MongoClient,
var url = "mongodb://localhost:27017/myDB";

var test = await MongoClient.connect(url);
module.exports = test;

I get this error:

var test = await MongoClient.connect(url);
             ^^^^^^^^^^^
SyntaxError: Unexpected identifier

MongoClient.connect(url) does return a promise

What I ultimately want to achieve is to create a node module that will connect to a mondoDB and will be usable as in the following example:

 var db = require('../utils/db');  //<-- this is what I want to create above
 col = db.collection('myCollection');

 module.exports.create = async fuction(data) {
   return await col.insertOne(data);
 }

Any suggestions?

回答1:

Is your module wrapper an async function as well? You need the await keyword to be in an async function.

回答2:

What about wrapping it in an async function?

var MongoClient = require('mongodb').MongoClient,
var url = "mongodb://localhost:27017/myDB";

var test = async function () {
  return await MongoClient.connect(url);
}

module.exports = test;

回答3:

I solved it like this, only opening one connection:

db.js

const MongoClient = require('mongodb').MongoClient;

let db;

const loadDB = async () => {
    if (db) {
        return db;
    }
    try {
        const client = await MongoClient.connect('mongodb://localhost:27017/dbname');
        db = client.db('dbname');
    } catch (err) {
        Raven.captureException(err);
    }
    return db;
};

module.exports = loadDB;

index.js

const loadDB = require('./db');

const db = await loadDB();
await db.collection('some_collection').insertOne(...);

来源：https://stackoverflow.com/questions/42215592/how-can-i-use-async-await-with-mongoclient

标签

node.js

mongodb

async-await