Why the server not accessing connection variable?

Question

I'm trying to retrieve data from database using Node.js restify framework. The server is running fine but when I visit http://localhost:8081/get I get this error:

{
  "code": "InternalError",
  "message": "connectionPool is not defined"
}

Here's my code:

server.js

require('./app/core/routes.js');

routes.js

var restify=require('restify');
var fs=require('fs');
var controllers = {};
     controllers_path = process.cwd() + '/app/controllers';
fs.readdirSync(controllers_path).forEach(function (file) {
    if (file.indexOf('.js') != -1) {
        controllers[file.split('.')[0]] = require(controllers_path + '/' + file);
    }
});
var server=restify.createServer();
server.get('/get', controllers.article.printHello);
server.listen(8081, function (err) {
    if (err)
        console.error(err);
    else
        console.log('App is ready at : ' + 8081);
});

article.js

var something2=require('../core/connection.js');
something2.something();
exports.printHello= function(req, res, next){
    connectionPool.getConnection(function (err, connection) {
        if (err) {
            res.send({
                Error: err,
                Message: "Can't connect Database."
            });
        } else {
            //queries
            connection.query("SELECT * FROM book", function (err, rows, fields) {
                res.send({
                    json: rows
                });
            });
        }
    });
};

connection.js

var mysql = require('mysql');
exports.something = function () {
    var connectionPool = mysql.createPool({
        host: 'localhost',
        user: 'root',
        password: '',
        database: 'books'
    });
}

The error seems to be correct, `connectionPool` isn't defined, it's defined in a different file, but that doesn't help much ? — adeneo, Nov 05 '16 at 13:37
I don't want to write the connection code in same file. I want to 'include' it. — Vikas, Nov 05 '16 at 13:39
CMD console is saying: 'Server is running'. Chrome's console: Failed to load resource: the server responded with a status of 500 (Internal Server Error) — Vikas, Nov 05 '16 at 13:40

adeneo · Accepted Answer · 2016-11-05T13:48:25.573

1

In your connection.js file, export the pool

var mysql = require('mysql');
exports.connectionPool = function() {
    return mysql.createPool({
        host: 'localhost',
        user: 'root',
        password: '',
        database: 'books'
    });
}

Then use it in your article.js file

var conn = require('../core/connection.js');
var pool = conn.connectionPool();

exports.printHello = function(req, res, next){
    pool.getConnection(function (err, connection) {
        if (err) { ...

edited Nov 05 '16 at 13:48

answered Nov 05 '16 at 13:39

adeneo

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I'll try and tell you. – Vikas Nov 05 '16 at 13:41
Are you sure it's okay? I'm getting error 'conn.connectionPool()` is not a function. – Vikas Nov 05 '16 at 13:45
You're right, it's whatever `createPool` returns. Wrapped it in a function, try it now. – adeneo Nov 05 '16 at 13:48
Could you answer this? http://stackoverflow.com/questions/40501764/why-is-it-showing-connection-not-defined – Vikas Nov 09 '16 at 07:26

score 0 · Answer 2 · answered Nov 05 '16 at 13:39

0

You have to return your variable connectionPool in your connection.js's something function.

connection.js

var mysql = require('mysql');
exports.something = function () {
    var connectionPool = mysql.createPool({
        host: 'localhost',
        user: 'root',
        password: '',
        database: 'books'
    });
return connectionPool; // notice here
}

article.js

var something2=require('../core/connection.js');
var connectionPool =  something2.something(); //notice here
exports.printHello= function(req, res, next){
    connectionPool.getConnection(function (err, connection) {
        if (err) {
            res.send({
                Error: err,
                Message: "Can't connect Database."
            });
        } else {
            //queries
            connection.query("SELECT * FROM book", function (err, rows, fields) {
                res.send({
                    json: rows
                });
            });
        }
    });
};

answered Nov 05 '16 at 13:39

hzitoun

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@Vikas Kumar I gave you the right answer for the beginning – hzitoun Nov 05 '16 at 13:53
Thank you very much. I should have thought so. – Vikas Nov 05 '16 at 13:54
Glad that helped :) – hzitoun Nov 05 '16 at 13:55
Do you know about restify and mysql? – Vikas Nov 05 '16 at 14:01
Maybe I could help, what is your question? – hzitoun Nov 05 '16 at 14:17
I'll let you know if I face any problem. Can you give your hangout id? – Vikas Nov 05 '16 at 14:25
Can you answer this? http://stackoverflow.com/questions/40501764/why-is-it-showing-connection-not-defined – Vikas Nov 09 '16 at 07:26

Why the server not accessing connection variable?

2 Answers2