I am new to nodejs and JavaScript. I am trying a very basic example of connecting MySQL to nodejs. I am using a npm jdbc package for this purpose. Below is the code snippet I am using for connection and getting below exception. Can you please help me on this.
Code:
var express = require('express');
var app = express();
var server = require('http').Server(app);
var https =require('http');
var io = require('socket.io')(server);
var kafka = require('kafka-node');
var cassandra = require('cassandra-driver');
var jdbc = new (require('jdbc'));
var jinst = require('jdbc/lib/jinst');
var Pool = require('jdbc/lib/pool');
var _ = require('underscore');
// var cors = require("cors");
app.use(express.static(__dirname + '/view'));
server.listen(3000);
app.use('/bower_components', express.static(__dirname + '/bower_components'));
app.get('/', function (req, res, next) { res.sendFile(__dirname + '/index.html');});
if (!jinst.isJvmCreated()) {
jinst.addOption("-Xrs");
jinst.setupClasspath(['../mysql-connector-java-5.1.39-bin.jar']);
}
var config = {
url: 'jdbc:mysql://localhost:3306/DB',
user : 'root',
password: 'root',
minpoolsize: 2,
maxpoolsize: 3,
drivername: 'com.mysql.jdbc.Driver'
};
//Initialize jdbc object
jdbc.initialize(config, function(err, res){ if (err){ console.log(err); } });
jdbc.open(function(err, conn) {
if (conn) {
//Run first query
jdbc.executeQuery('show databases', function(err, results){
if (err){ console.log(err); }
else if (results) { console.log(results); }
});
}else{
console.log('Connection object:' + conn);
console.log(err);
}
});
jdbc.close(function(err){
if(err) { console.log(err); }
else { console.log('Connection closed successfully!');}
});
Exception:
Field_Test\node_modules\jdbc\lib\pool.js:64
this._url = config.url;
^
TypeError: Cannot read property 'url' of undefined
at JDBC.Pool (<Dir>\node_modules\jdbc\lib\pool.js:64:21)
at new JDBC (<Dir>\node_modules\jdbc\lib\jdbc.js:6:8)
at Object.<anonymous> (Web\app.js:10:12)
at Module._compile (module.js:570:32)
at Object.Module._extensions..js (module.js:579:10)
at Module.load (module.js:487:32)
at tryModuleLoad (module.js:446:12)
at Function.Module._load (module.js:438:3)
at Module.runMain (module.js:604:10)
at run (bootstrap_node.js:394:7)
Your issue is with the require at the top, as per the docs https://www.npmjs.com/package/jdbc, when you create a new instance you need to pass the config parameters you can do it two ways
var config = {url: 'jdbc:mysql://localhost:3306/DB'}
var jdbc = new (require('jdbc'))(config);
or you can do it in line in the code
var Jdbc = require('jdbc');
...
var config = {url: 'jdbc:mysql://localhost:3306/DB'}
var jdbc = new Jdbc(config)
In the context of your code
var express = require('express');
var app = express();
var server = require('http').Server(app);
var https =require('http');
var io = require('socket.io')(server);
var kafka = require('kafka-node');
var cassandra = require('cassandra-driver');
var Jdbc = require('jdbc');
var jinst = require('jdbc/lib/jinst');
var Pool = require('jdbc/lib/pool');
var _ = require('underscore');
// var cors = require("cors");
app.use(express.static(__dirname + '/view'));
server.listen(3000);
app.use('/bower_components', express.static(__dirname + '/bower_components'));
app.get('/', function (req, res, next) { res.sendFile(__dirname + '/index.html');});
if (!jinst.isJvmCreated()) {
jinst.addOption("-Xrs");
jinst.setupClasspath(['../mysql-connector-java-5.1.39-bin.jar']);
}
var config = {
url: 'jdbc:mysql://localhost:3306/DB',
user : 'root',
password: 'root',
minpoolsize: 2,
maxpoolsize: 3,
drivername: 'com.mysql.jdbc.Driver'
};
var jdbc = new JDBC(config);
//Initialize jdbc object
jdbc.initialize(config, function(err, res){ if (err){ console.log(err); } });
jdbc.open(function(err, conn) {
if (conn) {
//Run first query
jdbc.executeQuery('show databases', function(err, results){
if (err){ console.log(err); }
else if (results) { console.log(results); }
});
}else{
console.log('Connection object:' + conn);
console.log(err);
}
});
jdbc.close(function(err){
if(err) { console.log(err); }
else { console.log('Connection closed successfully!');}
});