nodejs从函数导出变量

Question

我想从下面的“./models/devices-client.js”中导出变量“result_array”

var config = require('./config');
var MongoClient = require('mongodb').MongoClient;

MongoClient.connect(config.dbadmin_uri, function (err, db) {
if (err) throw err;
// console.log('Successfully connected');
var collection = db.collection('repvpn2');
collection.find().toArray(function (err, result_array) {
// console.log('Found results:', result_array);
    module.exports.Hosts = result_array;
    db.close();
    });
});    

但是当导入另一个文件时，它会打印“未定义”？

var Hosts = require('./models/devices-client').Hosts;
console.log(Hosts);

Answer 1

让您的模块接受异步函数回调。

// JavaScript source code
var config = require('./config');
var MongoClient = require('mongodb').MongoClient;
module.exports = function (callback) {
    MongoClient.connect(config.dbadmin_uri, function (err, db) {
        if (err) throw err;
        // console.log('Successfully connected');
        var collection = db.collection('repvpn2');
        collection.find().toArray(function (err, result_array) {
            // console.log('Found results:', result_array);
            callback(err, result_array);
            db.close();
        });
    });
}

---

require('./models/devices-client')(function callback(err,Hosts) {
   //Hosts Here
});