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I have database.js file that connects to db and manage connections I export connection and reuse it in my app
var mysql = require('mysql');
pool = mysql.createPool({
host: cfg.mysql.host,
user: cfg.mysql.user,
password: cfg.mysql.pass,
database: cfg.mysql.db,
port: cfg.mysql.port
});
function handleDisconnect() {
pool.getConnection(function(err, cnt) {
module.exports.connection = cnt;
});
pool.on('error', function (err) {
console.log(err);
});
};
handleDisconnect();
process.on('uncaughtException', function (err) {
console.error(err.code);
if(err.code === "PROTOCOL_CONNECTION_LOST")
handleDisconnect();
console.log("Node NOT Exiting...");
});
app.js
var db = require('./database');
app.get('/test', function(req, res) {
db.connection.query('SELECT * from table', function(err, result) {
console.log(result);
});
}
This works fine. My problem is when the mysql server disconnect. I handle this error by recalling the handleDisconnect() function to get a new connection. However, when that happens the connection is undefined in my app.js when I navigate to my browser /test
TypeError: Cannot call method 'query' of undefined
Thoughts?
598
You can simply put the connection back into pool following each query on your database server here's an example
db.js
var mysql = require('mysql');
var pool = mysql.createPool({
host : 'localhost',
user : 'root',
password : 'root',
database : 'test',
port: 8889
});
exports.getConnection = function(callback) {
pool.getConnection(function(err, connection) {
callback(err, connection);
});
};
app.js
var db = require('./db');
var http = require("http");
var server = http.createServer(function(request, response) {
db.getConnection(function(err, connection){
if(!err){
connection.query('SELECT * from users' , function(err, rows) {
var users = '';
for (var i = 0; i < rows.length; i++) {
users += rows[i].name + "<br />";
}
connection.release(); // always put connection back in pool after last query
response.writeHead(200, {"Content-Type": "text/html"});
response.write("<!DOCTYPE html>");
response.write("<html>");
response.write("<head>");
response.write("<title>Hello World Page</title>");
response.write("</head>");
response.write("<body>");
response.write(users);
response.write("</body>");
response.write("</html>");
response.end();
});
}else{
response.writeHead(200, {"Content-Type": "text/html"});
response.write("<!DOCTYPE html>");
response.write("<html>");
response.write("<head>");
response.write("<title>Hello World Page</title>");
response.write("</head>");
response.write("<body>");
response.write(err.toString());
response.write("</body>");
response.write("</html>");
response.end();
}
});
});
server.listen(9999);
console.log("Server is listening localhost:9999");
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