Currently I am experiencing a very frustrating issue with inserting data into my MySQL db using my NodeJS Express server.
My current setup is the following:
• MySQL server db on DigitalOcean droplet.
• NodeJS Express server on the same DigitalOcean droplet. It is being proxied by my Apache server that is on the same droplet. I keep Node server running with PM2.
I have been able to successfully read data from my db (i.e. SELECT * from performance);).
However, no matter what I try I cannot insert any data into my db. I have tried countless different solutions but none have worked.
Help would be greatly appreciated. Please ask any questions for further clarification if needed. Thank you.
My current code relating to MySQL:
server.js
var mysql = require('mysql');
var con = mysql.createConnection({
host: 'localhost',
user: 'user',
password: 'password',
database: 'analytics',
supportBigNumbers: true,
debug: true,
});
server.post('/performance', (req, res) => {
let d = req.body;
con.connect(function (err) {
if (err) throw err;
let q =
'INSERT INTO performance (uid, reqStart, resEnd, loadDuration) VALUES ?';
let values = []; // values to be inserted into db
// for testing purposes I have commented this out and tried inserting a hardcoded set of values instead
/*let body = JSON.parse(req.body); // json string body to json obj
body.data.forEach((x) => {
values.push([body.uid, x.reqStart, x.resEnd, x.loadDuration]);
});*/
values = [
[23299730, 8.3282343284, 8.121252244, 2.238932989],
[23288734, 8.3282343284, 8.121292244, 2.238932989],
];
con.query(q, [values], function (err, result) {
if (err) throw err;
});
});
res.send(d);
});
Update: I just ran my server manually (without PM2). This has allowed me to view console messages. For the first time I have seen a successful insert query. And upon running the server with PM2 I also get a successful query. However, on the second attempt I get PROTOCOL_ENQUEUE_HANDSHAKE_TWICE error.
Based on multiple other posts/articles I thought my code avoided this problem, but it's erroring on the line where I call con.connect(...). I have con.connect in a server.get route, but I haven't been hitting that endpoint at all.
After many hours of debugging, I think I found the problem.
Almost all tutorials showing how to connect to MySQL db using Node show that you should embed a con.query() call within a con.connect() call, and using connect() is recommended on MySQL docs.
However, con.query() also establishes a connection. Maybe it's because I am keeping the server live across multiple calls, but this results in the Handshake error I described in the post. Removing the wrapping con.connect() call fixed my problem.
Related
I'm very new to this backend stuff but I really want to know or else I can't sleep tonight or many other nightss.......
I'm tasked to build a rest API that will allow our web application to update our company's MySQL database remotely from any internet or client.
basically, the web application will be built using react framework that will allow users to take in some inputs and send them to the backend and update the MySQL database remotely.
so far, I have the rest API ready and inside this rest API i have included some mysql methods that will update the table in our database. it works fine.
but suddenly I couldn't find the reason why we need the rest API in the first place
below is the code I have...my question is
can't we just skip the express part? and directly connect the application to MySQL database using the mysql methods createConnection and then run db.query(sqlInsert) without running the app.get?
the only reason I can think of is that, if I do this, it will probably allow anyone to access the database from the browser's console. In this case, does it mean rest API is just like a filter that simply runs a server site after the user clicks the submit button, and then once the server runs it will then take the submitted information and run the db.query()? and then once that is complete, it will send back a response displayed on the server site saying its working?
const express = require('express');
const app = express();
const mysql = require('mysql');
const db = mysql.createConnection({
host:'the ip address of the computer that has the mySQL database',
user: 'the user name created in workbench',
password: 'the password created in workbench',
database: 'the database name',
port: '1234'
})
db.connect(function(err){
if(err){
console.log(err)
process.exit(1)
}
console.log("connected to mysql")
})
app.get('/', (req,res) => {
const sqlInsert = "INSERT INTO person123 (customerid, firstname, lastname) VALUES ('USv10', 'USv10', 'USv10');"
db.query(sqlInsert), (err, result) =>{
}
res.send('working')
})
app.listen(3001, () => {
console.log ('running on port 3001 yes')
})
yes you can connect with mysql without express and running restful api but
condition is that server will be running using a specific port.with only this block
of code your server is connected to databse.
var mysql = require('mysql');
var con = mysql.createConnection({
host:'the ip address of the computer that has the mySQL database',
user: 'the user name created in workbench',
password: 'the password created in workbench',
database: 'the database name',
port: '1234'
});
con.connect(function(err) {
if (err) throw err;
console.log("Connected!");
});
and this block is nesecary for running server on specific port
app.listen(3001, () => {
console.log ('running on port 3001 yes')
})
I'm trying to get the smallest ID (by world) that is not used via this SQL query:
"SELECT MAX(`objects`.`id`) as nextID FROM `objects` WHERE `objects`.`world`='1'"
NodeJS:
var mysql = require('mysql');
var pool = mysql.createPool({
connectionLimit: 10,
host: '********',
user: '*********',
password: '*******',
database: databaseName
});
function getNextObjectID(worldID, cb) {
var q = "SELECT MAX(`objects`.`id`) as nextID FROM `objects` WHERE `objects`.`world`='"+worldID+"'";
console.log(q);
pool.query(q, function(err, results, fields) {
console.log(err);
console.log(results);
console.log(fields);
});
}
Previously, I had a more in depth approach that included ids used previously, but it also was having this issue so I've reverted down to this simpler method.
I run this through node and phpmyadmin. When node is doing it, it automatically inserts the world id (and yes I print out the actual query and get that it is identical upon execution). When phpmyadmin executes it returns 14. When node executes its rarely 14 and most of the time null. I have no idea why it would change. All other queries behave normally.
There was an asynchronous delete being called by someone else, it was reading next id before a large amount of rows got inserted.
I am trying to learn node.js so that I can actually get started on working on my personal project. I have been trying to follow the examples in the book "Learning node.js" (by Marc Wandschneider). I, at this point, decided to forgo practicing his example, and go straight into using his code as framework for my practice code.
In my practice code, all I am trying to do is connect to my RDS database (no, I am not using Elastic Beanstalk, btw), and output contents of one of the tables. Seems simple enough, but when I whip up the code for it (based on the book), it seems to attempt connection, but get hung up in the process. This is my code:
var pool = require('generic-pool');
var async = require('async');
var mysql = require('mysql');
var host = "<database-name>.cu8hvhstcity.us-west-2.rds.amazonaws.com",
database = "<database-name>",
user = "<username>",
password = "<someLongPassword>";
var dbClient;
async.waterfall([
// 1. establish connection to database
function (callback) {
console.log("Connecting to database " + database + "...");
dbClient = mysql.createConnection({
host: host,
database: database,
user: user,
password: password,
port: 3306
});
dbClient.connect();
},
// 2. select all from a table (let's go for locations)
function (cb)
{
var query = "SELECT * FROM locations"
console.log("running query \"" + query + "\"...");
dbClient.query(query, cb);
},
function (rows, fields, callback)
{
console.log(fields);
for (var i = 0; i < rows.length; i++)
{
console.log(JSON.stringify(rows, null, '\t'));
}
}
], function (err, results) {
if (err)
{
console.log("An error occurred...");
console.log(err);
}
else
{
console.log("Everything successfully completed!");
}
dbClient.end();
})
This is better than first attempt, when I put a database member to the argument passed to mysql.createConnection(), and it complained that database was unknown. In neither case did either "An error occurred..." nor "Everything successfully completed!" output to the window.
Is there any async stuff going on that is resulting in some kind of non-terminating infinite loop or something? How do I fix this?
The book has an associated GitHub page
NOTE:
Neither my example nor the cited GitHub code make use of that pool variable, so it can simply be commented out. All you need to do to run this yourself is to say npm install async,npm install mysql (as well as creating a dummy RDS database to point to, that contains locations table) before copying, pasting, and running this code.
EDIT:
I fixed the issue with database. I realized that the name of the database used '_', not '-'. Same issue (code hangs) still persists...
I did the following:
In the second function in the array, I needed two parameters, not one.
I fixed thus:function(results, cb)
The third function simply needed to callback(null)
I have a nodejs server in Openshift with a MySQL cartridge. It seems to build with no problem, however, when I try to query the database, it seems to be doing nothing... It doesn't even give me an error, it's just does nothing. Here's my relevant code.
var mysql = require('mysql');
var connection = mysql.createConnection({
host: 'mysql://' + process.env.OPENSHIFT_MYSQL_DB_HOST + ':' + process.env.OPENSHIFT_MYSQL_DB_PORT + '/',
user: process.env.OPENSHIFT_MYSQL_DB_USERNAME,
password: process.env.OPENSHIFT_MYSQL_DB_PASSWORD,
database: 'revision',
multipleStatements: true,
debug : true
});
And in the appropriate route:
var stuff = 'abc';
connection.query('SELECT 1', function(err, rows, fields){
if (err) {
stuff = "ghi";
} else {
stuff = "def";
}
});
stuff = stuff + "done";
res.send(JSON.stringify(stuff));
It should return "defdone" or "ghidone", but it always returns "abcdone"... It's like it doesn't even get inside the function. I've tried several ways of doing this and none work. I've dumped the connection variable and it seems to be what's meant to be.
The reason I'm using SELECT 1 as the query string was to verify it was not a database error.
It seems the "issue" had to do with the asynchronous nature of node, as the final 2 instructions are executed before the query is completed. Furthermore, the configs seemed to be wrong after all, as I only had a "host" attribute with the whole url. I changed it into to 2 attributes - "host and "port", giving them the appropriate variables (process.env.OPENSHIFT_MYSQL_DB_HOST and process.env.OPENSHIFT_MYSQL_DB_PORT). It's working now!
I've begun playing around with Node.js lately, for many reasons but most importantly the ease at which I can write a chat-server utilising HTML5 WebSockets. However, I've been stuck for weeks with MySQL.
I'm currently using this MySQL client module: https://github.com/sidorares/nodejs-mysql-native
I've connected to the database and managed to store data using the following code:
// MySQL database
var db = require("mysql-native").createTCPClient(); // localhost:3306 by default
db.auto_prepare = true;
db.auth(dbName, dbUser, dbPass);
// Update the database
db.execute("UPDATE server_data SET value='" + new Date() + "' WHERE name='lastLoaded'");
How may I go about retrieving data from the database using a SELECT * FROM x WHERE y=z query?
Is there any specific reason you chose nodejs-mysql-native over node-mysql which is a really good node module. If there is none, then you should probably try node-mysql. I've tried it and it is great to start off using MySQL with Node. You could do something like:
var mysql = require('mysql');
var connection = mysql.createConnection({
host : 'localhost',
user : 'your_username',
password : 'your_password',
});
connection.connect();
connection.query("UPDATE server_data SET value=? WHERE name=?", [new Date(), 'lastLoaded'] function(err, result) {
if (err) throw err;
console.log('Result: ', result);
});
connection.end();
The advantage you get by using it this way is that you can prevent SQL injection, which is taken care of internally in node-mysql (by using the connection.escape() method).