nodejs中的mongoose disconnect on for loop end

Question

我想通过nodejs脚本用一些伪数据填充mongodb的一个实例，并想在for循环完成时调用mongoose.disconnect()，这样程序就不会因为mongoose实例而继续循环。

问题是，因为nodejs在当前代码中是非阻塞的，所以它调用for循环，然后继续并退出。我尝试过使用async lib，但是我不知道如何才能让它工作。

在node中执行此操作的正确方式是什么？

'use strict';
var mongoose = require('mongoose'),
    promise = require('promise');

mongoose.Promise = promise;
    var uri = 'mongodb://localhost:27017/test'

var test1Schema = new mongoose.Schema({
    name: String,
    type: String
});

var test2Schema = new mongoose.Schema({
    name: String,
    type: String
});

var test3Schema = new mongoose.Schema({
    name: String,
    type: String
});

var test1 = mongoose.model('test1', test1Schema);
var test2 = mongoose.model('test2', test2Schema);
var test3 = mongoose.model('test3', test3Schema);

function genRandom (high, low) {
    return Math.floor(Math.random() * (high - low) + low);
}

mongoose.connect(uri);

var _connection = mongoose.connection;

_connection.on('error', function (err) {
    console.log('Couldn\'t connect to the database %s - %s', uri, err);
});

_connection.on('open', function () {
    console.log('Connection open - ', uri);
});

_connection.on('close', function () {
    console.log('Closed mongoose connection');
});

var saveCallback = function (err) {
    if (err) {
    console.log('An error occured while saving %s', err);
    }
}

function genRecords (callback) {
    for (var i=0; i <= 5; i++) {
    new test1({
        name: 'test_' + i.toString(),
        type: genRandom(123, 321).toString()
    }).save(callback);

    new test2({
        name: 'test_' + i.toString(),
        type: genRandom(456, 654).toString()        
    }).save(callback);

    new test3({
        name: 'test_' + i.toString(),
        type: genRandom(789, 987).toString()        
    }).save(callback);
    }
}

genRecords(saveCallback)

mongoose.disconnect();

输出：

Connection open -  mongodb://localhost:27017/test
Closed mongoose connection
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed
An error occured while saving MongoError: server localhost:27017 sockets closed

Answer 1

您一定认为您使用的是异步函数。所以你正在准备你的save()函数，但是他们在断开之后完成了。

您需要等待save()调用结束。两种解决方案：

使用promises模块(例如，与)

• use

配合使用

Answer 2

使用此模块http://caolan.github.io/async/

然后执行以下代码。

async.times(5, function(i, done){
    //run in here your 3 instances with async.waterfall or something like this then go to next iteration
    methodToSave3Instances(i, done);
}, function(err) {
   mongoose.disconnect();
});

function methodToSave3Instances(i , cb) {
   async.waterfall([
     function(callback) {
        new test1({
          name: 'test_' + i.toString(),
          type: genRandom(123, 321).toString()
        }).save(callback);
     },
     function(callback) {
         new test2({
           name: 'test_' + i.toString(),
           type: genRandom(123, 321).toString()
        }).save(callback);
     },
    function(callback) {
        new test3({
           name: 'test_' + i.toString(),
           type: genRandom(123, 321).toString()
        }).save(callback);
    }
   ], function (err, result) {
       cb();
   });
}