Question

I’m having a try with node.js, and am using node-mysql to handle the connections.

So far I’m following the basic usage from the github page, but for some reason I can’t even get the most simple connection to function.

var mysql = require('mysql');

var db_host = 'localhost';
var db_user = 'root';
var db_pass = 'pass';
var db_name = 'mydb';

var client = mysql.createConnection({
  host: db_host,
  user: db_user,
  password: db_pass,
  database: db_name
});

console.dir(client); // prints a whole bunch of connection object data

client.connect(function(err) {
  // connected! (unless `err` is set)
  console.dir('got here!');  // prints nothing!
  if (err) console.dir(err);  // prints nothing!
});

client.query('SELECT 1', function(err, rows) {
  console.log('here'); // print nothing!
  console.dir(err); // prints nothing!
  console.dir(rows); // prints nothing!
});

client.end();
process.exit();

I’m very new to node so I’m sure I’m missing something obvious, but this seems pretty straightforward and I can’t even get the thing to break in an obvious way– it prints no errors– basically nothing happens.

Any advice?

Answer 1

Node is asynchronous, so it will not perform its actions linearly. By doing this:

client.connect //...
client.end // ...

You are starting the initial connection process and then immediately closing your client connection, before it has had time to connect. You need to perform your tasks asynchronously.

client.connect(function(err) {
  // connected! (unless `err` is set)
  console.dir('got here!');  // prints nothing!
  if (err)console.dir(err);  // prints nothing!

  client.query('SELECT 1', function(err, rows) {
    console.log('here'); // print nothing!
    console.dir(err); // prints nothing!
    console.dir(rows); // prints nothing!

    client.end();
    process.exit();
  });
});