NodeJS/express: server hanged after start running for a while - javascript

I made my service with express and webpack and it worked well at the beginning. The weird thing is that after a while the service(server) will hang. As the screenshot displays, no message code received.(server message screenshot)
And this happens again and again.
My app.js
var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var index = require('./routes/index');
var users = require('./routes/users');
var app = express();
var mysql = require('mysql');
var generals = require('./routes/generals');
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use('/generals', generals);
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', index);
app.use('/users', users);
// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});
// error handler
app.use(function(err, req, res, next) {
// set locals, only providing error in development
res.locals.message = err.message;
res.locals.error = req.app.get('env') === 'development' ? err : {};
// render the error page
res.status(err.status || 500);
res.render('error');
});
module.exports = app;
The here is the route file: generals.js
var express = require('express');
var bodyParser = require('body-parser');
var router = express.Router();
var pool = require('./connections');
router.get('/dropDownValue/', function(req, res, next) {
pool.getConnection(function(err, connection) {
connection.query("select * from drop_down_value order by id desc", function(err, rows) {
if (!err && rows.length > 0) {
res.json(rows);
} else {
res.json([]);
}
});
});
});
And the connections file:
var mysql = require('mysql');
var pool = mysql.createPool({
host: 'xxx',
user: 'xxx',
password: 'xxx',
database: 'xxx'
});
exports.getConnection = function (callback) {
pool.getConnection(callback);
};

When you use pool.getConnection(), once you're done with the connection (i.e. the query has finished), you need to release the connection back to the pool again:
pool.getConnection(function(err, connection) {
connection.query("select * from drop_down_value order by id desc", function(err, rows) {
connection.release(); // <- this
if (!err && rows.length > 0) {
res.json(rows);
} else {
res.json([]);
}
});
});
Otherwise, once you have performed 10 queries, there are no more connections available in the pool and it will start waiting (indefinitely) for connections to be released, hanging the requests.

Related

How do I pass data returned from a controller to Express' router?

I'm trying to make a catch-all of sorts to return data to my Author endpoint. If the url that is passed to the endpoint contains no query parameters, I want the router to return the full list of authors available. If the url contains firstName and lastName parameters, I want the controller to find the authors that match and, pass that data back to the router.
Currently if I send the urls http://localhost:3001/authors or http://localhost:3001/authors?firstName=tom&lastName=dooly, I get an error Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client.
Can anyone tell me why this is happening and how to fix it?
main:
var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var mongoose = require('mongoose');
var app = express();
var dev_db_url = 'mongodb://localhost:27017/'
var mongoDB = process.env.MONGODB_URI || dev_db_url;
mongoose.connect(dev_db_url);
mongoose.Promise = global.Promise;
var db = mongoose.connection;
db.on('error', console.error.bind(console, 'MongoDB connection error:'));
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
var index = require('./routes/index');
var users = require('./routes/users');
var feedEntries = require('./routes/feedEntries');
var authors = require('./routes/authors');
app.use('/', index);
app.use('/users', users);
app.use('/feedEntries', feedEntries);
app.use('/authors', authors);
// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not not Found');
err.status = 404;
next(err);
});
app.use(function(err, req, res, next) {
res.locals.message = err.message;
res.locals.error = req.app.get('env') === 'development' ? err : {};
res.status(err.status || 500);
res.render('error');
});
module.exports = app;
route:
var express = require('express');
var router = express.Router();
var authorController = require('../controllers/authorController');
authorController.findAuthorsByFirstAndLastName);
router.get('/', function (req, res) {
if(req.query.firstName||req.query.lastName) {
res.send(authorController.findAuthorsByFirstAndLastName(req,res));
}else{
res.send(authorController.author_list(req,res));
}
});
module.exports = router;
controller:
var Author = require('../models/author')
var async = require('async')
exports.author_list = function(req, res, next) {
Author.find({},function(err, authors) {
if (err){
res.send(err);
}
return.json(authors);
});
};
exports.findAuthorsByFirstAndLastName = function (req, res, next){
var query = {}
if(req.query.firstName||req.query.lastName) {
query = {$or:[{firstName:{$regex: req.query.firstName, $options: 'i'}},
{lastName:{$regex: req.query.lastName, $options: 'i'}}]}
}
else {
return res.status(500).send({ error: 'Unable to parse data'});
}
var firstName = req.body.firstName;
var lastName = req.body.lastName;
Author.find(query , function (err, authors) {
if(err) {
res.send(err);
}
res.json(authors);
});
};
You get cannot set headers after they are sent when you have two res.[whatever]s in your route. So you have res.send(functionCallThatAlsoDoesRes.Send). That's what's causing the error.
If you want a route to take multiple actions between the request and the response, you can write those as separate middlewares. Middlewares always take the arguments req, res, and next (a function that says to go to the next middleware in the list).
So, you might write:
authorController.findAuthorsByFirstAndLastName = function(req, res, next) {
if (!(req.query.firstName || req.query.lastName)) {
res.locals.getFullAuthorList = true
return next()
} else {
const query = /* whatever */
Author.find(query, (err, authors) => {
if (err) return next(err)
res.locals.authors = authors
next()
})
}
}
authorController.author_list = function(req, res, next) {
if (!res.locals.getFullAuthorList) return next() // if we already have authors we don't need to do anything
Author.find({}, (err, authors) => {
if (err) return next(err)
res.locals.authors = authors
next()
})
}
Then in your route, you'd say:
router.get('/', authorController.findAuthorsByFirstAndLastName, authorController.author_list, (req, res) => {
res.json({ authors: res.locals.authors })
})
If you haven't seen res.locals before, it's just a property on the response object that is available for you to attach things to. It persists throughout the request/response cycle and is cleared for each new request.

Why is express-myconnection returning "undefined" connection parameter?

I've got a basic Node JS app (as I'm just learning). I'm using express, express-generator, express-myconnection, and mysql.
The issue has to do with querying the database connection itself.
The app is designed using an MVC structure.
Edit: to start off, here is my "app.js":
var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var index = require('./routes/index');
//var users = require('./routes/users');
var app = express();
var connection = require('express-myconnection');
var mysql = require('mysql');
app.use(
connection(mysql,{
"host":"localhost",
"user":"root",
"password":"root",
"port":3306,
"database":"fruits"
},'request')
);
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'pug');
// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', index);
// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});
// error handler
app.use(function(err, req, res, next) {
// set locals, only providing error in development
res.locals.message = err.message;
res.locals.error = req.app.get('env') === 'development' ? err : {};
// render the error page
res.status(err.status || 500);
res.render('error');
});
module.exports = app;
I have a model file, "fruits.js":
var fruits = function(data, req){
this.data = data;
this.req = req;
}
fruits.prototype.data = {};
fruits.prototype.getAll = function(callback){
this.req.getConnection(function(err, connection){
console.log(connection);
//var q = connection.query("SELECT * FROM `fruits`", function(err, rows){
//callback(rows);
//});
});
};
module.exports = fruits;
Then I also have a controller file (index.js):
var express = require('express');
var router = express.Router();
var fruits = require('../models/fruits.js');
/* GET home page. */
router.get('/', function(req, res, next) {
res.render('index', { title: 'Express' });
});
/*GET fruits page */
router.get('/fruits',function(req, res, next){
var f = new fruits({}, req);
f.getAll(function(fruitsObj){
console.log(fruitsObj);
res.render('fruits',{
"title":"Fruits!",
"fruits":fruitsObj
});
});
});
module.exports = router;
What happens is whenever the fruits route is navigated to, I can't query the database. It says that the "connection" from "this.req.getConnection" is "undefined".
Is there any reason why I can't retrieve the database connection and query it based on the contents of these two files? I'm positive I have all my packages installed. I even ran npm install for all them again to make sure.
Thanks for your help in advance.

"req.getConnection is not a function" Node.js

Im having trouble connecting Node.js application with sql database.
Error occurs is "req.getConnection is not a function".
I am trying to get data from the database the moment I click on a certain page (eg.users).
My code is as below
app.js
var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var flash = require('express-flash');
var session = require('express-session');
var expressValidator = require('express-validator');
var methodOverride = require('method-override');
var connection = require('express-myconnection');
var mysql = require('mysql');
var routes = require('./routes/index');
var users = require('./routes/users');
var app = express();
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(session({secret:"mysecretpass"}));
app.use(flash());
app.use(expressValidator());
app.use(cookieParser());
app.use(require('less-middleware')(path.join(__dirname, 'public')));
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', routes);
app.use('/users', users);
app.use(methodOverride(function(req, res){
if (req.body && typeof req.body === 'object' && '_method' in req.body)
{
var method = req.body._method;
delete req.body._method;
return method;
}
}));
/*-----------------------------------------
* Connection peer, register as middleware
* type koneksi:single,pool and request
-----------------------------------------*/
app.use(
connection(mysql,{
host:'localhost',
user:'root',
password:'',
port:3306,
database:'stores'
},'single')
);
// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});
// error handlers
// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: err
});
});
}
// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: {}
});
});
module.exports = app;
routes/index.js
var express = require('express');
var router = express.Router();
/* GET home page. */
router.get('/', function(req, res, next) {
res.render('dashboard', { title: 'Dashboard' });
});
router.get('/admin_users', function(req, res, next) {
req.getConnection(function(err,connection){
var query = connection.query('SELECT * FROM users',function(err,rows)
{
if(err)
var errornya = ("Error Selecting : %s ",err );
req.flash('msg_error', errornya);
res.render('admin_users',{title:"Admin Users",data:rows});
});
//console.log(query.sql);
});
});
module.exports = router;
You are adding the express-myconnection middleware after your routes middleware. Middleware is executed in the order it is added, and as such the getConnection function is not defined on the req object until after your express-myconnection middleware is executed.
Simply move the connection middleware above the usage of routes, ie.
app.use(
connection(mysql,{
host:'localhost',
user:'root',
password:'',
port:3306,
database:'stores'
},'single')
);
app.use('/', routes);
app.use('/users', users);

Connection between 2 different servers Express.js and node js

I have a Experss.js framework and Node.js with a request to MS SQL database on the server side.
I want to get a data(in JSON or array) from server and send to Cliend side.
I don't understand how can I write routers for another server on the Client side.
server.js
npm start
http://localhost:5000/
Code:
var sql = require("mssql");
var express = require('express');
var app = express();
var http = require('http')
var query = "SELECT AVG([sta_waittime]) AS Spalte FROM [DialogMaster_TEST].[dwh].[anruf_stat] WHERE CONVERT(DATE,sta_timestamp) = CONVERT(DATE,CONVERT(DATE,'2016-08-01')) ";
app.get('/', function (req, res) {
sql.connect("mssql://log:pas#db/TEST").then(function() {
// Query
new sql.Request().query(query).then(function(recordset) {
var a = [];
a.push(recordset[0].Spalte);
res.send(a); // **number**
}).catch(function(err) {
// ... query error checks
});
}).catch(function(err) {
// ... connect error checks
});
});
var server = app.listen(5000, function () {
console.log('Server is running..');
});
Server site in Browser:
My app.js file.
var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var routes = require('./routes/index');
var users = require('./routes/users');
var app = express();
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', routes);
app.use('/users', users);
//app.get('/');
// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});
// error handlers
// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: err
});
});
}
// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: {}
});
});
module.exports = app;
You need only 1 server(REST server). Just use node.js server.
Read it:
REST

NodeJS - get property for Mongodb not working while connecting

I am new to NodeJS and ExpressJS. I am following this tutorial http://cwbuecheler.com/web/tutorials/2013/node-express-mongo/ for creating and connecting mongodb with nodejs. Everything works perfectly(DB data inserting through command line,package.json config) except db connection, it throws undefined error.
var monk = require('monk');
var db = monk('localhost:27017/deno');
I check this in console like this console.log(db) it shows 'undefined' in index.js
My app.js is :
var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
// New Code
var mongo = require('mongodb');
var monk = require('monk');
var db = monk('localhost:27017/Fujitsu');
var routes = require('./routes/index');
var users = require('./routes/users');
var app = express();
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
// Make our db accessible to our router
app.use(function(req,res,next){
req.db = db;
next();
});
app.use('/', routes);
app.use('/users', users);
// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});
// error handlers
// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: err
});
});
}
// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: {}
});
});
module.exports = app;
routes/index.js is
var express = require('express');
var router = express.Router();
/* GET home page. */
router.get('/', function(req, res, next) {
res.render('index', { title: 'Express' });
});
/************ Customized starts Here **********/
/* GET Userlist page. */
router.get('/userlist', function(req, res) {
var db = req.db;
console.log(db);
var collection = db.get('usercollection');
collection.find({},{},function(e,docs){
res.render('userlist', {
"userlist" : docs
});
});
});
/******** Customized - Ends here ***********/
module.exports = router;
Please anyone of you tell me the solution because now I'm struggling with this.
Thanks In Advance.

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