javascript - Node.js 域在连接时显示来自数据库的事件消息

Question

我是 Node.js 领域的新手，我正在尝试它们。我正在尝试让 mainDomain 在数据库上显示成功的消息。现在，当我启动 express.js 时，没有错误并且一切运行正常。但在成功连接数据库后，该消息并未按应有的方式显示:

db.js:

var mongoose = require( 'mongoose' );
var EventEmitter = require('events').EventEmitter;
var ee = new EventEmitter();


function connectDatabase() {
    var dbURI = 'mongodb://localhost/database';
    mongoose.connect(dbURI);

    mongoose.connection.on('connected', function () {
        ee.emit('message', 1, 2, 3);
       // console.log('Mongoose default connection open to ' + dbURI);
    });

    mongoose.connection.on('error',function (err) {
        console.log('Mongoose default connection error: ' + err);
    });

    mongoose.connection.on('disconnected', function () {
        console.log('Mongoose default connection disconnected');
    });

    process.on('SIGINT', function() {
        mongoose.connection.close(function () {
            console.log('Mongoose default connection disconnected through' +
                        ' app termination');
            process.exit(0);
        });
    });
}   
module.exports.connectDatabase = connectDatabase;

<小时/>

app.js:

var express = require('express');
var morgan = require('morgan');
var fs = require("fs");
var createDomain = require("domain").create;
var app = express();

app.use(morgan('dev'));
app.use(express.static(__dirname + '/app/static/views'));
app.use(express.static(__dirname + '/app/static'));
app.use(express.static(__dirname + '/app/images'));
app.use(express.static(__dirname + '/app'));

var apiScript = require('./app/scripts/api_scripts/call_all_api.js');
var db = require(__dirname + '/app/data/db.js');

var mainDomain = new createDomain();

mainDomain.run(function () { 
    db.connectDatabase(); 
    mainDomain.on('message', function(msg) {
        console.log('yoyoyoyo');
    });

});

mainDomain.run(function () {
    mainDomain.on('error', function(er) {
        console.log('error, but oh well', er.message);
    });

    var server = app.listen(9000, function() {
            console.log('Listening on port %d', server.address().port);
    });
});

更新:如果我使用 ee.emit('error') 而不是 ee.emit('message', 1, 2, 3);，我可以让它捕获错误。我不明白为什么我不能发出 ee.emit('message');

Answer 1

您需要替换这些行:

mainDomain.on('message', function(msg) {
    console.log('yoyoyoyo');
});

关于他们

db.on('message', function(msg) {
    console.log('yoyoyoyo');
});