I want to have a server running to make some entries in a database. I havent done that before. Im using node.js, express for the server and mysql with node-mysql and host it on uberspace as a low-cost webhosting service. When im starting the server with 'nohup node app.js &' everything seems to work fine, but after some time, I dont get any response from the server in a webbrowser anymore. I think the server just hang up and I want to restart it automatically. Here the simple code for my app.js:
var express = require('express');
var app = express();
var mysql = require('mysql');
var connection = mysql.createConnection({
host : '***',
database: '***',
user : '***',
password: '***',
port: 3306
});
connection.connect(function(err) {
console.log(err);
});
app.get('/test', function(req,res) {
var post = {ID: 1, User: "testuser"};
var query = connection.query('INSERT INTO testtabelle123 SET ?', post, function(err, results){
console.log(err);
});
console.log(query.sql);
res.send(query.sql);
});
I guess I simply just have to make a little change for automatically restart in the code and maybe use some sort of middleware/tool for that. Can you tell me what to do? Havent found simple solutions on SO so far.
Problem occurs because mysql is closing connection when there is no connection (after sometime). Add this to make connection alive forever:
setInterval(function () {
connection.query('SELECT 1', [], function () {})
}, 5000)
Relevant issue: https://github.com/felixge/node-mysql/issues/1337
Related
I am very new to programming so I do apologize if this is a really simple question.
So, I have been trying to connect my React Native application to the MySQL Database using Node and Express server, but I keep on getting the following error (I have checked other stackoverflow questions as well, but nothing has helped):
Error
I have checked my host name and port number multiple times and the all the information seems to be correct. I am not sure what is wrong with the following code:
var express = require("express");
var app = express();
var mysql = require("mysql");
var bodyParser = require("body-parser");
const { application } = require("express");
app.use(bodyParser.json({ type: "application/json" }));
app.use(bodyParser.urlencoded({ extended: true }));
var connection = mysql.createConnection({
host: '127.0.0.1', // Your connection adress (localhost).
port: "3306",
user: "root", // Your database's username.
password: "", // Your database's password.
database: "birthdays", // Your database's name.
});
connection.connect(function (error) {
if (error) console.log(error);
else console.log("connected");
});
// Starting our server.
app.listen(4547, () => {
console.log("Go to http://localhost:4547/dinners so you can see the data.");
});
app.get("/users", function (req, res) {
con.query("select * from users", function (error, rows, fields) {
if (error) console.log(error);
else {
console.log(rows);
res.send(rows);
}
});
});
I run this code by typing "node fileName.js" in the terminal.
I don't know if this is helpful, but I have also connected by MySQL database to MySQL Workbench.
Any help is appreciated!
Hello Stacksoverflowers,
I have a problem to connect my server.js file to Mysql via Express.
I've already insatlled mysql and express via npm.
when i run my server.js
The only thing it says in my console (MacOS default terminal) is:
"node server running now - using http://localhost:3000"
(I got no errors)
and my webpage also showing correct - "Node Server running - startpage" in the browser.
The problem is that they say nothing like "Connected to the MySQL server" or "Timeout: error messages" ?? (look at #3)
// Dan k
//#1
// My codes from server.js
const express = require('express');
const mysql = require('mysql');
const hostname = "localhost:";
const port = 3000;
//#2
// create connection to DB
const connection = mysql.createConnection({
host: "localhost",
user: 'root',
password: 'root',
port: 3000
});
//#3
// Connect to DB
connection.connect(function(err) {
if (!err) {
console.log('Connected to the MySQL server.');
}
else if (err)
{
return console.error('Timeout: ' + err.message);
}
});
// Routing with Express
const app = express();
//#4
// Startpage (root)
app.get('/', function(request, response){
response.send('Node Server running - startpage...');
response.end();
})
connection.end();
//#5
app.listen(port, (err) => {
if(err) throw err;
console.log("node server running now - using http://"+(hostname)+ .
(port)");
});
I got what is causing the issue. You are using the same port number 3000 to connect to your mysqlDB and at the same time using the same port to run your nodejs application.
This does throw an error but it takes a really long time to throw the error.
So the simple answer here is that the port that you are mentioning in your createConnection() method is incorrect and needs to be changed. This port should be port number on which your mysql DB is running. From the error it is clear that your mysql DB is not running on port 3306. You can check this post to figure out which port is your mysql DB running on. https://serverfault.com/questions/116100/how-to-check-what-port-mysql-is-running-on. Below is a reference for you. Please see the comments.
// create connection to DB
const connection = mysql.createConnection({
host: "localhost",
user: 'root',
password: 'root',
port: 3000 // You need to change this and put in the correct port number.
});
running into some issues trying to figure out an Azure Function (node.js-based) can connect to our mysql database (also hosted on Azure). We're using mysql2 and following tutorials pretty much exactly (https://learn.microsoft.com/en-us/azure/mysql/connect-nodejs, and similar) Here's the meat of the call:
const mysql = require('mysql2');
const fs = require('fs');
module.exports = async function (context, req) {
context.log('JavaScript HTTP trigger function processed a request.');
if (req.query.fname || (req.body && req.body.fname)) {
context.log('start');
var config = {
host:process.env['mysql_host'],
user: process.env['mysql_user'],
password: process.env['mysql_password'],
port:3306,
database:'database_name',
ssl:{
ca : fs.readFileSync(__dirname + '\\certs\\cacert.pem')
},
connectTimeout:5000
};
const conn = mysql.createConnection(config);
/*context.log(conn);*/
conn.connect(function (err) {
context.log('here');
if (err) {
context.error('error connecting: ' + err.stack);
context.log("shit is broke");
throw err;
}
console.log("Connection established.");
});
context.log('mid');
conn.query('SELECT 1+1',function(error,results,fields) {
context.log('here');
context.log(error);
context.log(results);
context.log(fields);
});
Basically, running into an issue where the conn.connect(function(err)... doesn't return anything - no error message, no logs, etc. conn.query works similarly.
Everything seems set up properly, but I don't even know where to look next to resolve the issue. Has anyone come across this before or have advice on how to handle?
Thanks!!
Ben
I believe the link that Baskar shared covers debugging your function locally
As for your function, you can make some changes to improve performance.
Create the connection to the DB outside the function code otherwise it will create a new instance and connect every time. Also, you can enable pooling to reuse connections and not cross the 300 limit that the sandbox in which Azure Functions run has.
Use the Promises along with async/await
You basically can update your code to something like this
const mysql = require('mysql2/promise');
const fs = require('fs');
var config = {
host: process.env['mysql_host'],
user: process.env['mysql_user'],
password: process.env['mysql_password'],
port: 3306,
database: 'database_name',
ssl: {
ca: fs.readFileSync(__dirname + '\\certs\\cacert.pem')
},
connectTimeout: 5000,
connectionLimit: 250,
queueLimit: 0
};
const pool = mysql.createPool(config);
module.exports = async function(context, req) {
context.log('JavaScript HTTP trigger function processed a request.');
if (req.query.fname || (req.body && req.body.fname)) {
context.log('start');
const conn = await pool.getConnection();
context.log('mid');
await conn.query('SELECT 1+1', function(error, results, fields) {
context.log('here');
context.log(error);
context.log(results);
context.log(fields);
});
conn.release();
}
};
PS: I haven't test this code as such but I believe something like this should work
Debugging on serverless is challenging for obvious reasons. You can try one of the hacky solutions to debug locally (like Serverless Framework), but that won't necessarily help you if your issue is to do with a connection to a DB. You might see different behaviour locally.
Another option is to see if you can step debug using Rookout, which should let you catch the full stack at different points in the code execution and give you a good sense of what's failing and why.
guys. I am learning how to use Express to connect to remote MySQL. So, I started out doing it on my local machine (a local MySQL server). After I have succeeded on the local environment, I tried changing the the connection to a remote MySQL hosting (at DB4Free). Yes, I have succeeded on the localhost. However, whenever I run a Get/Post to the remote MySQL Server, my console show me the error below. I'll attach the related segment of codes below here. I have been trying it the whole afternoon.
Hope that someone here can enlighten on this matter. Thank you in advance guys :)
This is the error shown in my console
My file for connecting db is as below - ConnectionString.js
var mysql = require("mysql");
var pool = mysql.createPool({
connectionLimit : 100,
host : '85.10.205.173:3306',
user : '******* ',
password : '*******',
database : '*******',
});
exports.getConnection = function(callback) {
pool.getConnection(function(err, conn) {
if(err) {
return callback(err);
}
callback(err, conn);
});
};
Portion of my file for the routes and query is this
var express = require('express');
var router = express.Router();
var mysql = require('mysql');
var conn = require('../database/ConnectionString');
var result;
//Validate user login
router.get('/login', function(req, res, next) {
conn.getConnection(
function (err, client) {
client.query('SELECT * FROM mt_User', function(err, rows) {
// And done with the connection.
if(err){
console.log('Query Error');
}
res.json(rows);
client.release();
// Don't use the connection here, it has been returned to the pool.
});
});
});
Alright, I have found the issue. It seems that the mysql package in npm requires that the host and port to be defined separately. After tuning it to this code below for my ConnectionString.js file. It finally works.
var mysql = require("mysql");
var pool = mysql.createPool({
connectionLimit : 100,
host : '85.10.205.173',
port : 3306,
user : '*******',
password : '*******',
database : '*******',
});
exports.getConnection = function(callback) {
pool.getConnection(function(err, conn) {
if(err) {
return callback(err);
}
callback(err, conn);
});
};
I'm trying to connect to my local mysql database by using node.js on my website. I have installed node.js on my laptop. This is my code that is executed:
function registerUser()
{
var mysql = require("mysql");
var connection = mysql.createConnection( {
host: 'localhost',
user: 'root',
password: '',
database: 'Fountaint_News_Database',
port: 3306
});
connection.connect();
var query = connection.query('INSERT INTO registered_users VALUES ("test", 22)',
function(err, result, fields) {
if (err) throw err;
console.log('result: ', result);
});
connection.end();
console.log('Connection closed');
}
I haven't done anything else, I'm not sure if there is anything else to setup, but when I runt I just get this error "ReferenceError: Can't find variable: require".
I hope that someone can help me.
Are you running this code on the server side, not on the client don't you? I mean saving this file on a .js file, running via console via
node yourfile.js
after obviously a
npm install mysql
in the same directory?
Obviously you need to bind the registerUser() function to some event :)