I'm working on an node.js application with several dozen modules and using bunyan for logging (JSON output, multiple configurable streams). I've been looking for good examples of how to implement a instance across all the modules, but haven't seen what appears to be a really clean example I can learn from.
Below illustrates an approach that works, but seems quite inelegant (ugly) to me. I'm new to node & commonjs javascript in general, so looking for recommendations on how to improve it.
module: ./lib/logger
// load config file (would like this to be passed in to the constructor)
nconf.file({ file: fileConfig});
var logSetting = nconf.get('log');
// instantiate the logger
var Bunyan = require('bunyan');
var log = new Bunyan({
name: logSetting.name,
streams : [
{ stream : process.stdout,
level : logSetting.stdoutLevel},
{ path : logSetting.logfile,
level : logSetting.logfileLevel}
],
serializers : Bunyan.stdSerializers
});
function Logger() {
};
Logger.prototype.info = function info(e) { log.info(e) };
Logger.prototype.debug = function debug(e) { log.debug(e) };
Logger.prototype.trace = function trace(e) { log.trace(e) };
Logger.prototype.error = function error(e) { log.error(e) };
Logger.prototype.warn = function warn(e) { log.warn(e) };
module.exports = Logger;
module: main app
// create the logger
var logger = require('./lib/logger)
var log = new logger();
// note: would like to pass in options --> new logger(options)
module: any project module using logger
// open the logger (new, rely on singleton...)
var logger = require('./lib/logger');
var log = new logger();
or view the gist
any recommendations?
EDIT:
I've modified the constructor, making the singleton pattern explicit (rather than implicit as part of the 'require' behaviour.
var log = null;
function Logger(option) {
// make the singleton pattern explicit
if (!Logger.log) {
Logger.log = this;
}
return Logger.log;
};
and then changed the initialization to take an options parameter
// initialize the logger
Logger.prototype.init = function init(options) {
log = new Bunyan({
name: options.name,
streams : [
{ stream : process.stdout,
level : options.stdoutLevel},
{ path : options.logfile,
level : options.logfileLevel}
],
serializers : Bunyan.stdSerializers
});
};
Singleton pattern in nodejs - is it needed?
Actually, singleton is perhaps not needed in Node's environment. All you need to do is to create a logger in a separate file say, logger.js:
var bunyan = require("bunyan"); // Bunyan dependency
var logger = bunyan.createLogger({name: "myLogger"});
module.exports = logger;
Then, retrieve this logger from another module:
var logger = require("./logger");
logger.info("Anything you like");
if you are using express with node.js then you can try this.
By default, logging is disabled in Express. You have to do certain stuff to get logs working for your app. For access logs, we need to use the Logger middleware; for error logs we will use Forever.Hope it will help you..
Here is a good example How to Logging Access and Errors in node.js
Related
So I wanted to save a file on the client storage using Store.js.
I can change the date using store.set and i can log it to console to see the change, but then it's supposed to be saved in app data where it's not created.
I tried to get the Path where it's being saved and it's :
C:\Users\USER\AppData\Roaming\stoma2/Categories.json
I noticed that there is a "/" so I tried :
C:\Users\USER\AppData\Roaming\stoma2\Categories.json
and :
C:/Users/USER/AppData/Roaming/stoma2/Categories.json
But all 3 of them didn't work.
This is my Store.js :
const fs = require('browserify-fs');
var fs2 = require('filereader'),Fs2 = new fs2();
const electron = window.require('electron');
const path = require('path');
class Store {
constructor(opts) {
// Renderer process has to get `app` module via `remote`, whereas the main process can get it directly
// app.getPath('userData') will return a string of the user's app data directory path.
//const userDataPath = (electron.app || electron.remote.app).getPath('userData');
var userDataPath = (electron.app || electron.remote.app).getPath('userData');
for(var i=0;i<userDataPath.length;i++){
if(userDataPath.charAt(i)=="\\"){
userDataPath = userDataPath.replace("\\","/");
}
}
// We'll use the `configName` property to set the file name and path.join to bring it all together as a string
this.path = path.join(userDataPath, opts.configName + '.json');
this.data = parseDataFile(this.path, opts.defaults);
console.log(this.path);
}
// This will just return the property on the `data` object
get(key) {
return this.data[key];
}
// ...and this will set it
set(key, val) {
this.data[key] = val;
// Wait, I thought using the node.js' synchronous APIs was bad form?
// We're not writing a server so there's not nearly the same IO demand on the process
// Also if we used an async API and our app was quit before the asynchronous write had a chance to complete,
// we might lose that data. Note that in a real app, we would try/catch this.
fs.writeFile(this.path, JSON.stringify(this.data));
}
}
function parseDataFile(filePath, data) {
// We'll try/catch it in case the file doesn't exist yet, which will be the case on the first application run.
// `fs.readFileSync` will return a JSON string which we then parse into a Javascript object
try {
return JSON.parse(Fs2.readAsDataURL(new File(filePath)));
} catch(error) {
// if there was some kind of error, return the passed in defaults instead.
return data;
}
}
// expose the class
export default Store;
There might be a probleme fith js.writeFile() (well that's the source of probleme).
and this is my call :
//creation
const storeDefCat = new Store({
configName: "Categories",
defaults: require("../data/DefaultCategorie.json")
})
//call for the save
storeDefCat.set('Pizza',{id:0,path:storeDefCat.get('Pizza').path});
For now if possible,I might need to find another way to save the file.
And i tried : fs : It doesn't work for me for some reason (I get strange errors that they don't want to be fixed..) .
If anyone has an Idea then please I would be grateful.
So I managed to fix the probleme, Why fs was sending me errors about undefined functions?Why file wasn't getting created ? It has NOTHING to do with the code it self, but the imports...
To clearify, I was using :
const fs = require('fs');
And the solution is to make it like :
const fs = window.require('fs');
Just adding window. fixed all the problems .Since it's my first time using electron I wasn't used to import from the window but it seems it's necessary.And more over...There was no posts saying this is the fix.
I've made a ModulesManager to manage all my modules, so I don't have a huge list of requirements in the top of my "server.js", but every time I'm trying to access the manager's methods, my server crash and throw an error which is saying that my manager method isn't a function.
TypeError: moduleManager.sqlString is not a function
I'm not really sure what I'm doing wrong here, this might be a stupid error, I've tried to look online for an answer but everyone is saying something different and nothing work.
Modules Manager (manager.js):
const sqlSetup = require("./sqlSetup.js");
const sqlSafeString = require("./sqlString.js");
function Manager(){
this.sqlString = function(query){
return sqlSafeString.getSqlSafeString(query);
},
this.sql = function(){
return sqlSetup;
}
}
module.exports = Manager;
Module SQL (sqlSetup.js):
const SqlString = require('sqlstring');
function getSqlSafeString(query){
//format query to fit in MySQL
var format = SqlString.escape(query);
return format;
}
module.exports = getSqlSafeString;
This is a test for my Travis build that I'm trying to make, the module manager path is good, the problem is really in the "ModuleManager.js" which I don't understand...
require('dotenv').config();
const Discord = require("discord.js");
const client = new Discord.Client();
const token = process.env.MOISTY;
const moduleManager = require("../modules/manager.js");
const assert = require("assert");
console.log("MAKE SURE MOISTY IS OFFLINE!");
client.login(token);
client.on('ready', () => {
//confirm login
console.log("MOISTY:200");
//Assert
assert.deepEqual(moduleManager.sqlString("sample text"), "sample test");
//terminate the session
process.exit();
});
I'm not very used to module exports, so this might be an easy question...
There are multiple mistakes in your code.
module.exports = getSqlSafeString; sets the export to getSqlSafeString.
When you do require("./sqlString.js") you will get the value that was assigned to the exports so in your case the getSqlSafeString.
So if you want to access that function you would write:
const getSqlSafeString = require("./sqlString.js");
//...
return getSqlSafeString(query);`
module.exports = Manager; exports the function Manager but not an object of the type Manager, so moduleManager.sqlString would be equal to Manager.sqlString. If you only want to group the functions in one object, then using a constructor would not make much sense here anyway, so you should write it that way:
module.exports = {
sqlString : function(query){
return sqlSafeString.getSqlSafeString(query)
},
sql : function(){
return sqlSetup
}
};
If you really want to do create on Object of the type Manager then you need to write:
module.exports = new Manager
For you to be able to require something from module A at module B, you have to export that something at module A. You export it assigning it to module.exports.
Yout problem is you didn't export the Manager at the Manager module.
You could simple export Manager, but, because you seem to be using an instance of Manager:
const moduleManager = require("../modules/manager.js");
...
moduleManager.sqlString("sample text")
Then you must export an instance. Add to manager.js:
module.exports = new Manager();
You are putting the functions on an instance, ie this.sqlString is a property named sqlString on an instance of Manager. But you are not using Manager as a constructor, ie not doing new Manager() or in your case new moduleManager()
You can change your import code to like below
const moduleManager = new require("../modules/manager.js")();
Or change the export to:
module.exports = new Manager();
Then moduleManager will be an instance of Manager and will be able to use moduleManager.sqlString
I have troubles for creating a module which exposes functionalities for my Socket.IO library:
const sio = require('socket.io');
module.exports = function(server) {
const io = sio(server);
return {
register: function(namespace) {
let nsp = io.of(namespace);
nsp.on('connect', function(socket) {
// ...
}
}
}
}
The problem is now how do I make use of this in other modules? In my app.js
I create the server with Express and can instantiate the module with require('./mysocketio')(server) but not in other modules because server is not available there. What's a nice way to resolve these circular dependencies?
Well you can achieve those in various ways, like:
setting objects to global namespace. (altering global needs care)
Use module.exports and require the object in the other files. (can lead to circular dependency issues if not done properly)
pass the instance as arguments to the controllers, while requiring them in routes.
myModule.js Module which exposes functionalities of your Socket.IO library
const sio = require('socket.io');
module.exports = function(server) {
const io = sio(server);
return {
register: function(namespace) {
let nsp = io.of(namespace);
nsp.on('connect', function(socket) {
// ...
}
}
}
}
FLow 1: set the module in global namespace.
app.js
var app = require('express').createServer();
var io = require('./myModule')(app);
global._io = io;
app.listen(80)
controller.js
module.exports = function(io){
var that={};
/*
* Private local variable
* made const so that
* one does not alter it by mistake
* later on.
*/
const _io = global._io;
that.myAction = function(req,res){
_io.register('newRoom');
res.send('Done');
}
return that;
}
Flow 2: passing module as arguments.
app.js
var app = require('express').createServer();
var io = require('./myModule')(app);
require(./router.js)(app,io);
app.listen(80);
router.js
/*
* Contains the routing logic
*/
module.exports = function (app,io) {
//passing while creating the instance of controller for the first time.
var controller = require("./controller")(io);
app.get('/test/about',controller.myAction);
};
controller.js
module.exports = function(io){
var that={};
const _io = io;
that.myAction = function(req,res){
_io.register('newsRoom');
res.send('Done');
}
// everything attached to that will be exposed
// more like making public member functions and properties.
return that;
}
Flow 3: Setting io to global. Thus no need to pass server every time.
app.js
var app = require('express').createServer();
require('./myModule')(app);
require(./router.js)(app);
app.listen(80);
controller.js
// no need to pass the server as io is already initialized
const _io = require('./myModule')();
module.exports = function(io){
var that={};
that.myAction = function(req,res){
_io.register('newsRoom');
res.send('Done');
}
return that;
}
myModule.js
module.exports = function( server ) {
const _io = global._io || require('socket.io')(server);
if(global._io === undefined){
//initializing io for future use
global._io = _io;
}
return {
register: function(namespace) {
let nsp = _io.of(namespace);
nsp.on('connect', function(socket) {
// ...
}
}
}
}
Probably, the cleanest way is to pass is as arguments to the controllers, while requiring them in routes. Although 3rd flow seems promising but one should be care full while altering the global namespace.
It's not really a circular dependency; It's just that your module a) depends on another module that's not globally available and b) your module is presumably used in many places in your code.
Global
A possible solution (with downsides), is to just load your module once, and attach it to a global:
global.mysocketio = require('./mysocketio')(server);
This allows you to access global.mysocketio anywhere in your project, once it has been loaded. This is a construction that I personally use for an own logger construction; My logger is used in many places around my code, so I just keep it attached to global.log.
However, usage of globals is a bit dirty; It gives problems with namespace-separation (what is somewhere some code decides to use global.mysocketio itself), and it creates an 'invisible' dependency; Other code just assumes that a certain global will exist, and it's not that easy to find these dependencies.
Export
A nicer solution is to just pass the variable wherever needed. There are many ways to do this. I understand that your app.js doesn't have the server variable available, but it surely is including your express-code in some way. If you need the 'server' or 'mysocketio' available from app.js, just export it from your module where you are creating 'server'. Like:
module.exports.expressServerVar = server;
Just my 2 cents; Do you strongly disagree with me or am I missing something important? Let me know!
I'd use a factory or dependency injection. You could use something like jimple.
But here's an example without using any external dependencies. This is by no means the best code example but it should hopefully get the point across. I'd still recommend using jimple rather than this.
// app.js
var express = require('express');
var app = express();
var factory = require('./factory.js');
factory.setExpress(app); // This could also be done in the factory constructor. Or you could instanciate your express app in the factory.js class.
// factory.js
var socketIoModule = require('./your-socket-io-module.js')
function Factory() {
}
Factory.prototype.setExpress = function(app) {
this.app = app;
}
Factory.prototype.getSocketIOModule = function() {
return socketIoModule(this.app);
}
// By exporting it this way we are making it a singleton
// This means that each module that requires this file will
// get the same instance of factory.
module.exports = new Factory();
// some code that needs socket io module
var factory = require('./factory.js');
function() {
var socketIo = factory.getSocketIOModule();
socketIo.doStuff();
}
Approach that I use in my applications is exposing server and io instances from start script and reusing them in modules
// Setup servers.
var http = require('http').Server(app);
var io = require('socket.io')(http);
// Setup application.
require('./server/app')(app, express, io);
// Start listening on port.
http.listen(configs.PORT, function() {
console.log("Listening on " + configs.PORT);
});
Inside your modules you can use io instance to setup event handlers or emit events, something like this
module.exports = {
contest: function(io, contest) {
var namespace = io.of('/' + contest.id);
namespace.on('connection', function(socket) {
socket.on('word', function(data) {
...
});
});
}
};
For your sample
I would put this part in app.js or in js file that is used to start server
const sio = require('socket.io');
const io = sio(server);
and will have Socket.IO module like this
module.exports = function(server, io) {
return {
register: function(namespace) {
let nsp = io.of(namespace);
nsp.on('connect', function(socket) {
// ...
}
}
}
}
My sample
https://github.com/gevorg/typeitquick/blob/master/web.js
https://github.com/gevorg/typeitquick/blob/master/server/contest.coffee
https://github.com/gevorg/typeitquick/blob/master/server/io.coffee
I am writing test cases for NODE JS API. But wherever console.log() is there in routes or services of NODE JS File, it gets printed to CLI. Is there a way to mock these so that these won't get printed in CLI.
I have explored couple of libraries like Sinon, Stub for mocking. But couldn't grasp the working of those libraries.
You can override function entirely: console.log = function () {}.
You should not try to mock console.log itself, a better approach is for your node modules to take a logging object. This allows you to provide an alternative (ie. a mock) during testing. For example:
<my_logger.js>
module.exports = {
err: function(message) {
console.log(message);
}
}
<my_module.js>
var DefaultLogger = require('my_logger.js');
module.exports = function(logger) {
this.log = logger || DefaultLogger;
// Other setup goes here
};
module.exports.prototype.myMethod = function() {
this.log.err('Error message.');
};
<my_module_test.js>
var MyModule = require('my_module.js');
describe('Test Example', function() {
var log_mock = { err: function(msg) {} };
it('Should not output anything.', function() {
var obj = new MyModule(log_mock);
obj.myMethod();
});
});
The code here I've simplified, as the actual test isn't the reason for the example. Merely the insertion of alternative logging.
If you have a large codebase with lots of console.log calls, it is better to simply update the code as you add tests for each method. Making your logging pluggable in this way makes your code easier and more receptive to testing. Also, there are many logging frameworks available for node. console.log is fine during development when you just want to dump out something to see what's going on. But, if possible, try to avoid using it as your logging solution.
I could not find a solution which only hides the console.log calls in the module to be tested, and mocks none of the calls of the testing framework (mocha/chai in my case).
I came up with using a copy of console in the app code:
/* console.js */
module.exports = console;
/* app.js */
const console = require('./console');
console.log("I'm hidden in the tests");
/* app.spec.js */
const mockery = require('mockery');
var app;
before(() => {
// Mock console
var consoleMock = {
log: () => {}
}
mockery.registerMock('./console', consoleMock);
// Require test module after mocking
app = require('./app');
});
after(() => {
mockery.deregisterAll();
mockery.disable();
});
it('works', () => {});
You could do something along the lines of adding these before/after blocks to your tests, but the issue is that mocha actually uses console.log to print the pretty messages about the results of the test, so you would lose those
describe('Test Name', function() {
var originalLog;
beforeEach(function() {
originalLog = console.log;
console.log = function () {};
});
// test code here
afterEach(function() {
console.log = originalLog;
})
})
The problem is that your output would just look like
Test Name
X passing (Yms)
Without any intermediate text
I want to separate some functions into a file named helpers.js, in which I have put the below shown code. What should I do to access the app variable from inside my method in order to be able to fetch my config element named Path?
Helpers = {
fs: require('fs'),
loadFileAsString: function(file) {
return this.fs.readFileSync( app.set('Path') + file)+ '';
}
}
module.exports = Helpers;
So from what I see you need the app variable form Express. You can send it as a function param to loadFileAsString, for ex:
helpers.js
Helpers = {
...
loadFileAsString: function(file, app) {
return this.fs.readFileSync( app.set('Path') + file)+ '';
}
}
module.exports = Helpers;
some_file.js
app = express.createServer();
...
helpers = require('./helpers.js');
helpers.loadfileAsString(file, app);
If you want the app to be global though you can do that also: global.app = app and you can access app everywhere without sending it as a function param.