NodeJS – > left side monitor

yarn “ERROR: There are no scenarios; must have at least one.

November 30, 2020November 30, 2020 by devmin

If you have this error when running yarn, chances are you have installed the wrong yarn package which come from cmdtest, let’s remove it and install the correct one using npm

sudo apt remove cmdtest
npm install -g yarn

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Separate / Split express app.js into smaller files and put in different folders

October 13, 2020 by devmin

Imagine the original app.js is this long file, how to split app.js of express into smaller files is as following

var http = require('http'),
    path = require('path'),
    methods = require('methods'),
    express = require('express'),
    bodyParser = require('body-parser'),
    session = require('express-session'),
    cors = require('cors'),
    passport = require('passport'),
    errorhandler = require('errorhandler'),
    mongoose = require('mongoose');

var isProduction = process.env.NODE_ENV === 'production';

// Create global app object
var app = express();
var router = app.Router();

app.use(cors());

// Normal express config defaults
app.use(require('morgan')('dev'));
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

app.use(require('method-override')());
app.use(express.static(__dirname + '/public'));

app.use(session({ secret: 'conduit', cookie: { maxAge: 60000 }, resave: false, saveUninitialized: false  }));

if (!isProduction) {
  app.use(errorhandler());
}

if(isProduction){
  mongoose.connect(process.env.MONGODB_URI);
} else {
  mongoose.connect('mongodb://localhost/conduit');
  mongoose.set('debug', true);
}

var passport = require('passport');
var LocalStrategy = require('passport-local').Strategy;
var mongoose = require('mongoose');
var User = mongoose.model('User');

passport.use(new LocalStrategy({
  usernameField: 'user[email]',
  passwordField: 'user[password]'
}, function(email, password, done) {
  User.findOne({email: email}).then(function(user){
    if(!user || !user.validPassword(password)){
      return done(null, false, {errors: {'email or password': 'is invalid'}});
    }

    return done(null, user);
  }).catch(done);
}));


router.get('/user', auth.required, function(req, res, next){
  User.findById(req.payload.id).then(function(user){
    if(!user){ return res.sendStatus(401); }

    return res.json({user: user.toAuthJSON()});
  }).catch(next);
});

router.put('/user', auth.required, function(req, res, next){
  User.findById(req.payload.id).then(function(user){
    if(!user){ return res.sendStatus(401); }

    // only update fields that were actually passed...
    if(typeof req.body.user.username !== 'undefined'){
      user.username = req.body.user.username;
    }
    if(typeof req.body.user.email !== 'undefined'){
      user.email = req.body.user.email;
    }
    if(typeof req.body.user.bio !== 'undefined'){
      user.bio = req.body.user.bio;
    }
    if(typeof req.body.user.image !== 'undefined'){
      user.image = req.body.user.image;
    }
    if(typeof req.body.user.password !== 'undefined'){
      user.setPassword(req.body.user.password);
    }

    return user.save().then(function(){
      return res.json({user: user.toAuthJSON()});
    });
  }).catch(next);
});

/// catch 404 and forward to error handler
app.use(function(req, res, next) {
  var err = new Error('Not Found');
  err.status = 404;
  next(err);
});

/// error handlers

// development error handler
// will print stacktrace
if (!isProduction) {
  app.use(function(err, req, res, next) {
    console.log(err.stack);

    res.status(err.status || 500);

    res.json({'errors': {
      message: err.message,
      error: err
    }});
  });
}

// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
  res.status(err.status || 500);
  res.json({'errors': {
    message: err.message,
    error: {}
  }});
});

// finally, let's start our server...
var server = app.listen( process.env.PORT || 3000, function(){
  console.log('Listening on port ' + server.address().port);
});

Split passport and routes

var http = require('http'),
    path = require('path'),
    methods = require('methods'),
    express = require('express'),
    bodyParser = require('body-parser'),
    session = require('express-session'),
    cors = require('cors'),
    passport = require('passport'),
    errorhandler = require('errorhandler'),
    mongoose = require('mongoose');

var isProduction = process.env.NODE_ENV === 'production';

// Create global app object
var app = express();

app.use(cors());

// Normal express config defaults
app.use(require('morgan')('dev'));
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

app.use(require('method-override')());
app.use(express.static(__dirname + '/public'));

app.use(session({ secret: 'conduit', cookie: { maxAge: 60000 }, resave: false, saveUninitialized: false  }));

if (!isProduction) {
  app.use(errorhandler());
}

if(isProduction){
  mongoose.connect(process.env.MONGODB_URI);
} else {
  mongoose.connect('mongodb://localhost/conduit');
  mongoose.set('debug', true);
}

require('./config/passport');

app.use(require('./routes'));

/// catch 404 and forward to error handler
app.use(function(req, res, next) {
  var err = new Error('Not Found');
  err.status = 404;
  next(err);
});

/// error handlers

// development error handler
// will print stacktrace
if (!isProduction) {
  app.use(function(err, req, res, next) {
    console.log(err.stack);

    res.status(err.status || 500);

    res.json({'errors': {
      message: err.message,
      error: err
    }});
  });
}

// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
  res.status(err.status || 500);
  res.json({'errors': {
    message: err.message,
    error: {}
  }});
});

// finally, let's start our server...
var server = app.listen( process.env.PORT || 3000, function(){
  console.log('Listening on port ' + server.address().port);
});

var passport = require('passport');
var LocalStrategy = require('passport-local').Strategy;
var mongoose = require('mongoose');
var User = mongoose.model('User');

passport.use(new LocalStrategy({
  usernameField: 'user[email]',
  passwordField: 'user[password]'
}, function(email, password, done) {
  User.findOne({email: email}).then(function(user){
    if(!user || !user.validPassword(password)){
      return done(null, false, {errors: {'email or password': 'is invalid'}});
    }

    return done(null, user);
  }).catch(done);
}));

var mongoose = require('mongoose');
var router = require('express').Router();
var passport = require('passport');
var User = mongoose.model('User');
var auth = require('../auth');

router.get('/user', auth.required, function(req, res, next){
  User.findById(req.payload.id).then(function(user){
    if(!user){ return res.sendStatus(401); }

    return res.json({user: user.toAuthJSON()});
  }).catch(next);
});

router.put('/user', auth.required, function(req, res, next){
  User.findById(req.payload.id).then(function(user){
    if(!user){ return res.sendStatus(401); }

    // only update fields that were actually passed...
    if(typeof req.body.user.username !== 'undefined'){
      user.username = req.body.user.username;
    }
    if(typeof req.body.user.email !== 'undefined'){
      user.email = req.body.user.email;
    }
    if(typeof req.body.user.bio !== 'undefined'){
      user.bio = req.body.user.bio;
    }
    if(typeof req.body.user.image !== 'undefined'){
      user.image = req.body.user.image;
    }
    if(typeof req.body.user.password !== 'undefined'){
      user.setPassword(req.body.user.password);
    }

    return user.save().then(function(){
      return res.json({user: user.toAuthJSON()});
    });
  }).catch(next);
});

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Return value from Mongoose findOne sync call (parent-child dependency entity)

October 12, 2020October 12, 2020 by devmin

Rather than using methods chain and callback, from express router we can call to mongoose findOne using async await as following

we can then search for mongo, if found then use the object, not found then create new one and attach to the second entity.

// mongoose.model("Child", ChildSchema);
// mongoose.model("Parent", ParentSchema);

router.post('/create', async function (req, res, next) {
    const user = req.user;
    const childObject = req.body.object1;
    const parentObject = req.body.object2;
    console.log('create parent-child for user: ', user, ' from parent: ', parentObject, 'to child:', childObject);
    
    var parentEntity = await Parent.findOne({criteria1: parent.value1}).exec();
    if(!parentEntity) {
        parentEntity = new Parent(parentObject); 
        parentEntity.extra = 'extra';
        parentEntity.userId = user.id;      	
        parentEntity.save();
    }
  
    var childEntity = await Child.findOne({criteria1: child.value1}).exec();
    if(!childEntity) {
        childEntity = new Child(child);
        childEntity.extra = 'extra';
        childEntity.userId = user.id;
        childEntity.parentId = parentEntity.id;
        childEntity.save();
    }
});

This helps us solve the express mongoose mongodb object dependency issue

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List of USA states in Javascript

October 11, 2020October 11, 2020 by devmin

module.exports = Object.freeze({
    STATES: {
        "AL": "Alabama",
        "AK": "Alaska",
        "AS": "American Samoa",
        "AZ": "Arizona",
        "AR": "Arkansas",
        "CA": "California",
        "CO": "Colorado",
        "CT": "Connecticut",
        "DE": "Delaware",
        "DC": "District Of Columbia",
        "FM": "Federated States Of Micronesia",
        "FL": "Florida",
        "GA": "Georgia",
        "GU": "Guam",
        "HI": "Hawaii",
        "ID": "Idaho",
        "IL": "Illinois",
        "IN": "Indiana",
        "IA": "Iowa",
        "KS": "Kansas",
        "KY": "Kentucky",
        "LA": "Louisiana",
        "ME": "Maine",
        "MH": "Marshall Islands",
        "MD": "Maryland",
        "MA": "Massachusetts",
        "MI": "Michigan",
        "MN": "Minnesota",
        "MS": "Mississippi",
        "MO": "Missouri",
        "MT": "Montana",
        "NE": "Nebraska",
        "NV": "Nevada",
        "NH": "New Hampshire",
        "NJ": "New Jersey",
        "NM": "New Mexico",
        "NY": "New York",
        "NC": "North Carolina",
        "ND": "North Dakota",
        "MP": "Northern Mariana Islands",
        "OH": "Ohio",
        "OK": "Oklahoma",
        "OR": "Oregon",
        "PW": "Palau",
        "PA": "Pennsylvania",
        "PR": "Puerto Rico",
        "RI": "Rhode Island",
        "SC": "South Carolina",
        "SD": "South Dakota",
        "TN": "Tennessee",
        "TX": "Texas",
        "UT": "Utah",
        "VT": "Vermont",
        "VI": "Virgin Islands",
        "VA": "Virginia",
        "WA": "Washington",
        "WV": "West Virginia",
        "WI": "Wisconsin",
        "WY": "Wyoming"
    }
});

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Failed to serialize user into session Error: Failed to serialize user into session at Authenticator.serializeUser

October 11, 2020October 11, 2020 by devmin

When this error happened, beside the normal configuration for passport, you may want to add the following configuration

passport.serializeUser(function(user, done) {
    done(null, user);
});

passport.deserializeUser(function(user, done) {
    done(null, user);
});

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Nodemon expressjs not working

October 10, 2020October 10, 2020 by devmin

For ExpressJS 4, running nodemon app.js won’t work, use the following command:

nodemon www/bin 
# or 
nodemon

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Express extend layout

October 10, 2020October 10, 2020 by devmin

To create a layout that other view can inherit / extend from using Express EJS engine

## First create a project and install important libs
npm install express-generator -g
express --ejs --git extend-layout
cd extend-layout
npm install --save express-ejs-extend

## Make change to app.js
var createError = require('http-errors');
var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');

var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');

var app = express();

// view engine setup
app.engine('ejs', require('express-ejs-extend')); // add this line
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');

app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', indexRouter);
app.use('/users', usersRouter);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  next(createError(404));
});

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;

## Create views/layout.ejs
<!DOCTYPE html>
<html>
<body>
<%- content %>
</body>
</html>

## Change to views/index.ejs
<%# views/index.ejs %>
<% extend('layout') %>
<h1>Hello <%= title %></h1>

## Finally run and test
DEBUG=extend-layout:* npm start

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Writing an Express middleware

October 8, 2020October 8, 2020 by devmin

var express = require('express')
var app = express()

var myLogger = function (req, res, next) {
  console.log('LOGGED')
  next()
}

app.use(myLogger)

app.get('/', function (req, res) {
  res.send('Hello World!')
})

app.listen(3000

var express = require('express')
var app = express()

var requestTime = function (req, res, next) {
  req.requestTime = Date.now()
  next()
}

app.use(requestTime)

app.get('/', function (req, res) {
  var responseText = 'Hello World!<br>'
  responseText += '<small>Requested at: ' + req.requestTime + '</small>'
  res.send(responseText)
})

app.listen(3000)

var express = require('express')
var cookieParser = require('cookie-parser')
var cookieValidator = require('./cookieValidator')

var app = express()

async function validateCookies (req, res, next) {
  await cookieValidator(req.cookies)
  next()
}

app.use(cookieParser())

app.use(validateCookies)

// error handler
app.use(function (err, req, res, next) {
  res.status(400).send(err.message)
})

app.listen(3000)

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Express project structure

October 8, 2020October 8, 2020 by devmin

.
├── app.js
├── bin
│   └── www
├── package.json
├── public
│   ├── images
│   ├── javascripts
│   └── stylesheets
│       └── style.css
├── routes
│   ├── index.js
│   └── users.js
└── views
    ├── error.pug
    ├── index.pug
    └── layout.pug

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Create express app

October 8, 2020 by devmin

express --view=pug myapp

   create : myapp
   create : myapp/package.json
   create : myapp/app.js
   create : myapp/public
   create : myapp/public/javascripts
   create : myapp/public/images
   create : myapp/routes
   create : myapp/routes/index.js
   create : myapp/routes/users.js
   create : myapp/public/stylesheets
   create : myapp/public/stylesheets/style.css
   create : myapp/views
   create : myapp/views/index.pug
   create : myapp/views/layout.pug
   create : myapp/views/error.pug
   create : myapp/bin
   create : myapp/bin/www

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