Develop Reference

Connecting with the db only through javascript

var mysql = require('mysql');
var connection = mysql.createConnection({
host : 'localhost',
user : '',
password : '',
database : 'mejili'
});
connection.connect();
connection.query('SELECT * FROM cards where number = 1', function(err, rows, fields) {
if (!err)
console.log('The solution is: ', rows);
else
console.log('Error while performing Query.');
});
I have searched a lot and I still cant find a way to connect with the db only through js, not using node.

MySQL DB Pool with Node.js and Restify

I am currently developing a node.js backend for a mobile app with potentially many users. However it's my first time in developing node.js. I was following a tutorial on how to connect to a mysql database via mysql pools.
I am able to create a single mysql connection and do queries via my routes.
The problem arises once I establish the file structure mentioned in the tutorial:
dbConnect
-[models]
--users.js
-db.js
-server-ks
I am not getting an error message regarding the connection of the mysql database - even if I enter a wrong password.
// server.js
///////////////////////////// basic setup ///////////////////////////////////
var restify = require('restify');
var bodyParser = require('body-parser');
var mysql = require('mysql');
var db = require('./db');
var users = require('./models/users');
///////////////////////////// initilisation of the server ///////////////////////////////////
var server = restify.createServer({
name: 'testUsers',
});
server.use(restify.bodyParser({ mapParams: true }));
///////////////////////////// Säuberung der URL //////////////////////////////////////////
server.pre(restify.pre.sanitizePath());
///////////////////////////// MySQL Instanz starten //////////////////////////////////////////
db.connect(db.MODE_PRODUCTION, function (err) {
if (err) {
console.log('Unable to connect to MySQL.')
process.exit(1)
} else {
server.listen(8080, function () {
console.log('Listening on port 8080 ...')
})
}
})
///////////////////////////// implementation of the routes ///////////////////////////////////
function send(req, res, next) {
var test = users.getAll();
res.json({ test: 'Hello ' + req.params.name });
return next();
};
My DB.js file looks the following:
var mysql = require('mysql'),
sync = require('async')
var PRODUCTION_DB = 'userDB',
TEST_DB = 'userDB'
exports.MODE_TEST = 'mode_test'
exports.MODE_PRODUCTION = 'mode_production'
var state = {
pool: null,
mode: null,
}
exports.connect = function (mode, done) {
state.pool = mysql.createPool({
connectionLimit: 50,
host: 'localhost',
user: 'user',
password: 'password',
database: 'userDB' // test
//mode === exports.MODE_PRODUCTION ? PRODUCTION_DB : TEST_DB
})
state.mode = mode
done()
}
exports.get = function () {
return state.pool
}
Could it be, that the tutorial spared out an essential part in utilizing mysql pools and node.js?
Thanks in advance for at least trying to answer that question.
Are there better methods sequelize(?) available to create performant connections to a MySQL database?

It looks like creating the pool object does not actually connect to the database. A big clue is that the createPool function is not asynchronous, which is what you would expect if it was actually connecting at that moment.
You have to make use of the returned pool object to perform a query, which IS asynchronous.
From the documentation:
var mysql = require('mysql');
var pool = mysql.createPool({
connectionLimit : 10,
host : 'example.org',
user : 'bob',
password : 'secret',
database : 'my_db'
});
pool.query('SELECT 1 + 1 AS solution', function(err, rows, fields) {
if (err) throw err;
console.log('The solution is: ', rows[0].solution);
});

MySQL Node JS Async Issues

I think I'm having some async issues with implementing a function that gets all rows from a table in a mysql database using node js. I'm using the node-mysql module.
I have already googled this, and have tried doing the accepted answer on this question says but still no luck. It tells me undefined is not a function on the throw err. Anyone know what the issue here is?
var express = require('express');
var mysql = require('mysql');
var router = express.Router();
router.get('/people', function(req, res, next) {
getAllPeople(function(err, people) {
res.json(people);
});
});
function getAllPeople(cb) {
var connection = mysql.createConnection({
host : 'localhost',
user : 'root',
password : 'root',
database : 'people'
});
connection.connect();
connection.query('SELECT * from people', function(err, rows, fields) {
connection.close();
cb(err, rows);
});
}
module.exports = router;

There is no close() method defined in connection object. Use connection.end()

Global objects with Node.js + Express

I'm studying Node.js + Express, coding a basic login example. My /login route is set inside the routes/login.js file:
var express = require('express');
var router = express.Router();
var mysql = require('mysql');
var connectionpool = mysql.createPool({
host : 'localhost',
user : 'user',
password : 'pass',
database : 'database'
});
router.post('/', function(req,res){
connectionpool.getConnection(function(err, connection) {
if (err) {
console.error('CONNECTION error: ',err);
res.statusCode = 503;
res.send({
result: 'error',
err: err.code
});
} else {
// Do something
}
});
});
module.exports = router;
I was wondering: how can I make the mysql or the connectionpool visible in the entire application? I don't want to redeclare them on each route file I'll create. I'm looking something like an include or require method.
Any idea?

Create a separate module to act as an interface to retrieving SQL connections like so:
var mysql = require('mysql');
var connectionpool = mysql.createPool({
host : 'localhost',
user : 'user',
password : 'pass',
database : 'database'
});
exports.getConnection = function (callback) {
connectionpool.getConnection(callback);
};
Then in another file:
var connections = require('./connections');
connections.getConnection(function (err, c) {
// Use c as a connection
c.query("select * from table limit 10 ",function(err,rows){
//this is important release part
c.release();
if(!err) {
console.log(rows);
}
});
});

mySQL base authentication error in express framework

Recently I put my interest in node.js and learned a great about it and quickly move to the express framework. I've tried to connect my express application with mysql database and succeeded. Now I try to authenticate a simple login from connected with mysql database but I can't do that. Still don't get it why it is happening. Bellow here is the code I've used. A help will be greatly welcome.
var mysql = require('mysql');
connection = mysql.createConnection({
host: 'localhost',
user: 'root',
database: 'express_db',
password: '12345'
});
connection.connect();
exports.admin_login = function (req, res) {
res.render('./admin/login', {title: 'Please provide your credentials to login'});
};
exports.admin_home = function (req, res) {
var parse = req.body;
var name = parse.name;
var password = parse.password;
var sql = "select * from user where name = " + connection.escape(name) + " and password = " + connection.escape(password);
connection.query(sql, function (err, results) {
if (err) throw err;
if (name == results[0].name && password == results[0].password) {
req.session.regenerate(function () {
req.session.name = results[0].id;
res.render('./admin/home', {username: results[0].name});
});
}
});