I have a NodeJS + ExpressJS + Socket.IO server and I am trying to divide my different namespaces into different modules.
Essentially I want to require the socket.io library in server.js, but have access to the io variable from my modules like this:
server.js
var app = require('express')();
var jwt = require('jsonwebtoken');
var server = require('http').Server(app);
var fs = require('fs');
var io = require('socket.io')(server);
var bodyParser = require('body-parser');
var _log = require('./logging/loggly.js').Client();
// Global NS
var SK = {
Namespaces:{}
};
var Migrations = require('./sockets/migrations');
var Backups = require('./sockets/backups');
var Cloudmanager = require('./sockets/cloudmanager');
SK.Namespaces[Migrations.NS] = Migrations;
SK.Namespaces[Backups.NS] = Backups;
SK.Namespaces[Cloudmanager.NS] = Cloudmanager;
....
....
migrations.js
var exports = module.exports = {};
///////////////////////////////////////////////
//
// Migrations Namespace
//
///////////////////////////////////////////////
exports.NS = 'migrations';
exports.socket = io.of('/'+exports.NS); // PROBLEM IS 'io' IS UNDEFINED HERE
exports.socket.on('connection', function(socket){
});
I have basically the same code in all 3 of my socket.io namespaces, but I don't have access to the io variable that is used in server.js. Is there a way to have access here? Do I just use a require()? Whats the best way to achieve this functionality?
Thank you
You can export a function from migrations.js that accepts the io value as a parameter:
module.exports = function (io) {
var socket = io.of('/'+exports.NS);
socket.on('connection', function(socket){});
return {
NS: 'migrations',
socket: socket,
};
};
Then simply require and invoke this function in your server.js:
var Migrations = require('./sockets/migrations')(io);
Related
My express app logic is separated into a separate file from the instantiation of the express server, so I'm having issues with accessing socket.io within this app file. Should I just move the socket.io implementation into index.js or is it possible to keep that logic in app.js?
index.js
const http = require('http');
const app = require('./app');
const server = http.createServer(app);
const io = require('socket.io')(server);
const config = require('./utils/config');
const logger = require('./utils/logger');
app.set('socketio', io);
server.listen(config.PORT, () => {
logger.info(`Listening on port ${config.PORT}`);
});
app.js
const express = require('express');
const config = require('./utils/config');
const middleware = require('./utils/middleware');
const app = express();
app.use(middleware.requestLogger);
const io = app.get('socketio');
io.on('connection', (socket) => {
io.emit('test', { test: 'test' });
});
app.use(middleware.errorHandler);
module.exports = app;
You have a load order problem. You are loading app.js into index.js BEFORE you create and set io as an app property. So, when app.js tries to use the io property, it hasn't yet been set.
The way you have things split between the files, you've created a circular dependency. You can't create io until you've created the server, but you can't create the server until you have the app which is in app.js. So, you can't create io before you load app.js.
There are lots of ways around this. I find it kind of weird that you're creating the server in one file and the app object in another file since the two are fully required to make an operational server. So, I'd rearrange how those things are done like this:
// index.js
const http = require('http');
const app = require('express')();
const server = http.createServer(app);
const io = require('socket.io')(server);
app.set('socketio', io);
require('./app.js')(app);
const config = require('./utils/config');
const logger = require('./utils/logger');
server.listen(config.PORT, () => {
logger.info(`Listening on port ${config.PORT}`);
});
And, then modify app.js like this:
const config = require('./utils/config');
const middleware = require('./utils/middleware');
module.exports = function(app) {
app.use(middleware.requestLogger);
const io = app.get('socketio');
io.on('connection', (socket) => {
io.emit('test', { test: 'test' });
});
app.use(middleware.errorHandler);
}
There are 100 other ways to organize the code to fix this. Exporting a function that you can call and passing that function one or more arguments is one way to help control the timing of these circular dependencies.
i am using nodejs loopback framework.i want to run a cron job.i created a custom js file for this cron job in server/boot folder.but when manually i run this file(xyz). app is undefined.my code is below
var app = require('../server.js');
console.log(">>>>>>>>>>>>>>in test")
var subscription = app.models.UserNotification;
console.log(">>>>>>>>>>>..in manage")
var datasource=subscription.dataSource;
var query="SELECT DISTINCT userId FROM users_subscription";
datasource.connector.query(sql,function (err, data) {
console.log(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>data is>>>>>",data);
})
here is my server.js file
var bodyParser = require('body-parser');
var loopback = require('loopback');
var boot = require('loopback-boot');
var app = module.exports = loopback();
var passport = require('passport');
var bodyParser = require('body-parser').urlencoded({
extended: true
})
app.use(bodyParser)
app.use(loopback.context());
app.use(loopback.token());
var path = require("path");
var url = require('url');
var http = require('http');
var fs = require('fs');
var request = require('request');
app.start = function() {
// start the web server
return app.listen(function() {
app.emit('started');
var baseUrl = app.get('url').replace(/\/$/, '');
console.log('Web server listening at: %s', baseUrl);
if (app.get('loopback-component-explorer')) {
var explorerPath = app.get('loopback-component-explorer').mountPath;
console.log('Browse your REST API at %s%s', baseUrl, explorerPath);
}
});
};
app.use(loopback.static(path.resolve(__dirname, '../client')));
app.use(loopback.static(path.resolve(__dirname, '../admin')));
app.use(loopback.static(path.resolve(__dirname, '../other-dir')));
boot(app, __dirname, function(err) {
if (err) throw err;
if (require.main === module) app.start();
});
Thanks,
It's really impossible to say for sure since you don't include the code that is included with:
var app = require('../server');
(which would be the most important code to include if the require returns undefined) but if app is undefined then it means that the module is loaded but its module.exports is undefined.
Do you export anything from that module?
Are you sure that it is really app that is undefined and not, say, app.models?
Without knowing the code in question those are the most reasonable things to investigate.
Update
If you don't export anything from your server.js (which was my suspection in my answer above, but now you confirmed it with you code and comment) then after this line:
var app = require('../server.js');
you will not be able to use app.models.UserNotification
If you want to use app.models in the code that requires server.js, then you'll have to add:
module.exports.models = SOMETHING;
in your server.js code. You don't seem to have anything called models in server.js, you don't export anything as module.exports.models, so you can't expect app.models to be defined in your code that does:
var app = require('../server.js');
I want to separate my app in to the parts to have something like MVC... Currently I figured out exports works and how to communicate between different files. The one thing i cant understand is that how to use constants in global scope? Currently i have something like this:
// start.js
const ROOT_DIR = __dirname;
const APP_DIR = ROOT_DIR + '/app/';
const MODULES_DIR = '/usr/local/lib/node_modules/';
const APP_PORT = 4935;
var server = require(APP_DIR + 'server.js');
server.start();
// server.js
exports.start = function() {
var express = require(MODULES_DIR + 'express'),
app = express(),
http = require('http'),
server = http.createServer(app),
io = require(MODULES_DIR + 'socket.io').listen(server),
fs = require('fs'),
path = require('path');
server.listen(APP_PORT);
app.use(express.static(ROOT_DIR + '/assets'));
app.get('/', function (req, res) {
res.sendfile(ROOT_DIR + '/views/index.html');
});
}
Is it possible to automatically assign this constants to server.js or i need to pass them as variables?
I think, you need create file with constants and use him as require file in begin a other module.
File consts.js
exports.CONST_1 = 42,
exports.CONST_2 = 123;
In the module where necessary:
var consts = require('path_to_consts.js');
var my_var = consts.CONST_1 + consts.CONST_2;
So all global variables will be in one place
Object.defineProperty(global, 'MY_CONST', { value : 123 })
P.S. Please, don't do this
Javascript constants won't work globally across files in Node.js. You need to pass them to the function.
// start.js
const ROOT_DIR = __dirname;
const APP_DIR = ROOT_DIR + '/app/';
const MODULES_DIR = '/usr/local/lib/node_modules/';
const APP_PORT = 4935;
var server = require(APP_DIR + 'server.js');
server.start(MODULES_DIR,APP_PORT,ROOT_DIR);
// server.js
exports.start = function(MODULES_DIR,APP_PORT,ROOT_DIR) {
var express = require(MODULES_DIR + 'express'),
app = express(),
http = require('http'),
server = http.createServer(app),
io = require(MODULES_DIR + 'socket.io').listen(server),
fs = require('fs'),
path = require('path');
server.listen(APP_PORT);
app.use(express.static(ROOT_DIR + '/assets'));
app.get('/', function (req, res) {
res.sendfile(ROOT_DIR + '/views/index.html');
});
}
This is method is same as suggested by #user3040347 but little different.
Here, you need create file with constants and use him as require file in begin of a module in which you want to use.
File consts.js
CONST_1 = 42,
CONST_2 = 123;
module.exports = {};
In the module where necessary:
var consts = require('path_to_consts.js');
var my_var = CONST_1 + CONST_2;
//Here you can access directly
I need to access my socket.io instance in some differents files, how do you make it works?
Here is what i tried:
main.js
var app = express();
var sockets = require('./sockets');
sockets.listen(app)
sockets.js
var io = require('socket.io');
exports.listen = function(app) {
io = io.listen(app);
//...
}
exports.io = io;
SomeClass.js
var io = require('./sockets').io;
var SomeClass = function() {
var Clients = io.sockets.clients('room');
//io is undefined...
}
exports.SomeClass = SomeClass;
In your file, io.sockets is undefined because you are starting your server incorrectly. Socket.IO expects a HTTP server instance, and you are instead passing an Express instance. You are also trying to change a variable after it has been exported, and that does not work. This is what you should be doing:
var http = require('http');
var express = require('express');
var app = express();
var server = http.createServer(app);
var io = require('socket.io').listen(server):
server.listen(80);
If you still wanted to split this up into files, you would have to put your Socket.IO instance in your main application, and pass it to other modules when requiring them.
I'm building a small node.js/express project and have a function in configure.js that sets configuration options in my express app. For example:
server.js
var express = require('express');
var server = ('./configure');
var app = express();
server.configure(app);
configure.js
exports.configure = function(app) {
app.set('title', 'Server');
};
This doesn't work but I hope it explains what I'm trying to do. I want to make changes to the app instance in server.js. How do I do this?
EDIT:
Okay I think i can get this all working if i understand why this isn't working. Is it to do with timing of the callback? The second console.log() isn't called.
configure.js
var fs = require('fs');
var StringDecoder = require('string_decoder').StringDecoder;
var decoder = new StringDecoder('utf8');
function configure(app) {
var config = module.exports = {};
fs.readFile('config.txt', function (err, data) {
if (err) throw err;
config.title = decoder.write(data)
console.log(config.title)
});
if(config.title) console.log(config.title);
//app.set('title', config.title)
}
module.exports = function (app) {
configure(app);
};
server.js
var express = require('express');
var cfg = require('./configure');
var fs = require('fs');
var app = express()
cfg(app)
(config.txt is echo 'server' > config.txt)
What you have should actually work.
As for your question about using multiple functions, you can export and call each separately. This can be useful when timing is important (such as if other setup steps need to occur that aren't specified in configure.js):
// configure.js
exports.configure = function (app) {
// ...
};
exports.attachMiddlware = function (app) {
// ...
};
// server.js
var express = require('express');
var server = require('./configure');
var app = express();
server.configure(app);
server.attachMiddlware(app);
You can also define a single entry function as the exported object which calls the functions needed within configure.js. This can possibly keep server.js cleaner by isolating the maintenance within configure.js:
function configure(app) {
// ...
}
function attachMiddleware(app) {
// ...
}
module.exports = function (app) {
configure(app);
attachMiddleware(app)
};
var express = require('express');
var configure = require('./configure');
var app = express();
configure(app);
I would avoid that and just do a json object:
app.js
var cfg = require('./config');
app.set('title', cfg.title);
config.js
var config = module.exports = {};
config.title = 'Server';