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db.getConnection is not a function

I am trying to make a post request to my first app, but every time I go to make the post, it gives me this error: TypeError: db.getConnection is not a function
I have tried all of stack overflows suggestions, but I still can't seem to get it to work after messing around with the code for the last 2 days. I am a beginner so please forgive me, but here is what my code looks like...
my db.js looks like this....
var mysql = require('mysql');
var mainDb = mysql.createPool({
host : process.env.mysql_host,
user : process.env.mysql_user,
password : process.env.mysql_pwd,
database : process.env.mysql_db
});
exports.getConnection = function(callback) {
mainDb.getConnection(function(err, connection) {
if (err) {
console.error('error connecting: ' + err.stack);
return;
}
callback(err, connection);
});
};
and my register.js code looks like this...
var express = require('express');
var router = express.Router();
var db = require(__dirname, 'models/db');
var bodyParser = require('body-parser');
app.use(bodyParser.urlencoded({
extended: false
}));
app.use(bodyParser.json());
router.get('/register', function(req, res, next) {
res.render('register', { title: 'Register for a free account' });
});
router.post('/register', function(req, res) {
var input = JSON.parse(JSON.stringify(req.body));
var today = new Date();
var users = {
"username": req.body.username,
"email":req.body.email,
"password":req.body.password,
"created":today,
"modified":today
};
db.getConnection(function(err, connection) {
connection.query('INSERT INTO users SET ? ', users, function(err, result) {
connection.release();
if (err) { return console.error(err); }
});
});
res.redirect('/index');
});
module.exports = router;
I don't know if my app.js is relevant for this question, but it looks like this...
const express = require('express');
http = require('http');
path = require('path');
session = require('express-session');
app = express();
mysql = require('mysql');
bodyParser = require('body-parser');
db = require(__dirname, 'models/db')
var index = require('./routes/index');
var register = require('./routes/register');
app.use('/', index);
app.use('/', register);
var engine = require('ejs-mate');
app.engine('ejs', engine);
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: false}));
app.use(express.static(path.join(__dirname, 'public')));
var server = http.createServer(app);
var port = 8995;
server.listen(port);
module.exports = app;
When I start app.js I get no errors, only when I make my post request from my form, the error shows up in my browser. Please help!

At db.js you are exporting only a function. But at register.js, you are trying to use db as if it was an object.
To solve your problem, at db.js, just export an object, instead of a function:
function getConnection(callback) {
mainDb.getConnection(function(err, connection) {
if (err) {
console.error('error connecting: ' + err.stack);
return;
}
callback(err, connection);
}
module.exports = { getConnection };

You don't need use getConnection method only exports the pool, according the documentation.
https://github.com/mysqljs/mysql

rethinkdb changesfeed in express with socket.io displaying [object object]

I'm using express.js, rethinkdb, thinky, socket.io. Trying to notify the index page of any changes that happens in the db. So I use rethinkdb changesfeed (and I can see the updates in console.log) but the cursor/feed is showing object object instead of the data.
When I pass the feed results to the socket.emit, it displays [object object]?
I read and implemented the code that comes from the rethinkdb blog (https://www.rethinkdb.com/blog/cats-of-instagram/) but it is not working.
Please scroll down to the bottom with socket.io header
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 r = require('rethinkdb');
// *********** Thinky code*********************//
var changeStream = require("rethinkdb-change-stream");
var thinky = require('thinky')()
var type = thinky.type;
var r = thinky.r;
//thinky model
var User = thinky.createModel('User', {
author: type.string()
});
/*
User.changes().then(function (feed) {
feed.each(function (error, doc) {
if (error) {
console.log(error);
process.exit(1);
}
if (doc.isSaved() === false) {
console.log("The following document was deleted:");
console.log(JSON.stringify(doc));
}
else if (doc.getOldValue() == null) {
console.log("A new document was inserted:");
console.log(JSON.stringify(doc));
}
else {
console.log("A document was updated.");
console.log("Old value:");
console.log(JSON.stringify(doc.getOldValue()));
console.log("New value:");
console.log(JSON.stringify(doc));
}
});
}).error(function (error) {
console.log(error);
process.exit(1);
});
*/
//*********End Thinky Code ******************//
// Mongodb Example http://www.guru99.com/node-js-mongodb.html
var MongoClient = require('mongodb').MongoClient
var url = 'mongodb://localhost/EmployeeDB';
var routes = require('./routes/index');
var users = require('./routes/users');
var app = express();
//attach socket server to express server so it interacts with clients requests and responses
app.io = require('socket.io')();
// 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(__dirname + '/public/favicon.ico'));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(require('stylus').middleware(path.join(__dirname, 'public')));
app.use(express.static(path.join(__dirname, 'public')));
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: {}
});
});
/* )))))))))))))))) socket.io Header ((((((((((((((((((( */
app.io.on('connection', function (socket) {
r.connect(host = 'localhost', port = 28015, db = 'test').then(function (conn) {
this.conn = conn;
return r.table("User").changes().run(this.conn).then(function (cursor) {
cursor.each(function (err, item) {
console.log(item);
//if (item && item.new_val)
socket.emit("message-from-server", { greeting: item });
});
})
});
// socket.emit("message-from-server", { greeting: "Say whatever here- it will show on the index page"});
});
module.exports = app;

From your code:
console.log(item);
//if (item && item.new_val)
socket.emit("message-from-server", { greeting: item });
This tells me that item is probably an object so when you pass it to the web api to add to the DOM it renders the object reference [object Object] because its expecting a string (not an object). So you can pull out the info you want from item using . syntax for objects or [<index>] syntax for arrays, or you could do something like item.toString() to attempt to turn the whole thing into a string. It really depends on the structure of item and how you are adding it to the DOM. You could do it on the client side or do it before it's emitted from your server.

Express Js: Router.use() Requires Middleware function

I am developing an application in Express Js. When I try to run the application I get this error:
My app.js file is like this:
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();
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(express.static(path.join(__dirname, 'public')));
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);
});
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
});
});
}
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: {}
});
});
var server = app.listen(3000, function() {
var host = server.address().address;
var port = server.address().port;
console.log('Example app listening at http://%s:%s', host, port);
});
module.exports = router;
My index.js is like this:
var express = require('express');
var router = express.Router();
/* GET home page. */
router.get('/', function (req, res, next) {
res.render('index', {title: 'Polls'});
});
router.get("/list", function (req, res, next) {
Poll.find({}, 'question', function (error, polls) {
res.json(polls);
});
});
router.get("/poll", function (req, res, next) {
var pollId = req.params.id;
// Find the poll by its ID, use lean as we won't be changing it
Poll.findById(pollId, '', {lean: true}, function (err, poll) {
if (poll) {
var userVoted = false,
userChoice,
totalVotes = 0;
// Loop through poll choices to determine if user has voted
// on this poll, and if so, what they selected
for (c in poll.choices) {
var choice = poll.choices[c];
for (v in choice.votes) {
var vote = choice.votes[v];
totalVotes++;
if (vote.ip === (req.header('x-forwarded-for') || req.ip)) {
userVoted = true;
userChoice = {_id: choice._id, text: choice.text};
}
}
}
// Attach info about user's past voting on this poll
poll.userVoted = userVoted;
poll.userChoice = userChoice;
poll.totalVotes = totalVotes;
res.json(poll);
} else {
res.json({error: true});
}
});
});
router.get("/create", function (req, res, next) {
var reqBody = req.body,
// Filter out choices with empty text
choices = reqBody.choices.filter(function (v) {
return v.text != '';
}),
// Build up poll object to save
pollObj = {question: reqBody.question, choices: choices};
// Create poll model from built up poll object
var poll = new Poll(pollObj);
// Save poll to DB
poll.save(function (err, doc) {
if (err || !doc) {
throw 'Error';
} else {
res.json(doc);
}
});
});
module.exports = router;
And user.js is this:
var express = require('express');
var router = express.Router();
/* GET users listing. */
router.get('/', function(req, res, next) {
res.send('respond with a resource');
});
module.exports = router;
I tried to find my solution on SO, but couldn't. Feel free to tell me if i need to provide any other file. Any help?

You should define routes in your index.js like you do in user.js.
app.use('/', routes) in your code expects routes to be an instance of a Router, but you're exporting an object with functions instead of that.
So your index.js file should have the following structure:
var express = require('express');
var router = express.Router();
router.get("/", function (req, res) {
res.render('index');
});
router.get("/list", function(req, res) {/*list implementation*/});
....
module.exports = router;

Using MongoDB, Express, Node.Js and GridFS-stream for storing video and picture files

I am creating a single page application using JavaScript(JQuery) and need to store large video files which size exceed 16Mb. I found that need to use GridFS supporting large files. As I am the new one to MongoDB I am not sure how to use GridFS. There are some good tutorials on creating applications using Node.js, MongoDB and Express but cant find any describing how to use GridFS with MongoDB (not mongoose), Express and Node.js. I managed to put up stuff for uploading files in the BSON-document size limit of 16MB. This is what I have:
var express = require('express');
var path = require('path');
var bodyParser = require('body-parser');
var mongo = require('mongodb');
var monk = require('monk');
var Grid = require('gridfs-stream');
var db = monk('localhost:27017/elearning');
var gfs = Grid(db, mongo);
var routes = require('./routes/index');
var users = require('./routes/users');
var courses = require('./routes/courses');
var app = express();
// 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(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);
app.use('/courses', courses);
// 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;
And, for example, the courses file is as the following:
var express = require('express');
var router = express.Router();
/* GET courses listing */
router.get('/courselist', function(req, res) {
var db = req.db;
var collection = db.get('courselist');
collection.find({},{},function(e,docs){
res.json(docs);
})
});
/* POST courses data */
router.post('/courselist', function(req, res) {
var db = req.db;
var collection = db.get('courselist');
collection.insert(req.body, function(err, result){
res.send(
(err === null) ? { msg: '' } : { msg: err }
);
});
});
/* Delete courses data */
router.delete('/courselist/:id', function(req, res) {
var db = req.db;
var collection = db.get('courselist');
var userToDelete = req.params.id;
collection.remove({ '_id' : userToDelete }, function(err) {
res.send((err === null) ? { msg: '' } : { msg:'error: ' + err });
});
});
module.exports = router;
I would be extremely grateful for your help, if you could tell how should I edit above files in order to utilize GridFS and be able to get, upload and delete video and picture files from my elearning database.

You can do direct uploading without using mongoose using gridfs-stream as simple as:
var express = require('express'),
mongo = require('mongodb'),
Grid = require('gridfs-stream'),
db = new mongo.Db('node-cheat-db', new mongo.Server("localhost", 27017)),
gfs = Grid(db, mongo),
app = express();
db.open(function (err) {
if (err) return handleError(err);
var gfs = Grid(db, mongo);
console.log('All set! Start uploading :)');
});
//POST http://localhost:3000/file
app.post('/file', function (req, res) {
var writeStream = gfs.createWriteStream({
filename: 'file_name_here'
});
writeStream.on('close', function (file) {
res.send(`File has been uploaded ${file._id}`);
});
req.pipe(writeStream);
});
//GET http://localhost:3000/file/[mongo_id_of_file_here]
app.get('/file/:fileId', function (req, res) {
gfs.createReadStream({
_id: req.params.fileId // or provide filename: 'file_name_here'
}).pipe(res);
});
app.listen(process.env.PORT || 3000);
for complete files and running project:
Clone node-cheat direct_upload_gridfs, run node app followed by npm install express mongodb gridfs-stream.
OR
Follow baby steps at Node-Cheat Direct Upload via GridFS README.md

Very late but I found previous answer outdated. I'm posting this because this might help newbies like me. To run it, please follow previous answers guide. All credit goes to #ZeeshanHassanMemon.
var express = require('express'),
mongoose = require('mongoose'),
Grid = require('gridfs-stream'),
app = express();
Grid.mongo = mongoose.mongo;
conn = mongoose.createConnection('mongodb://localhost/node-cheat-db');
conn.once('open', function () {
var gfs = Grid(conn.db);
app.set('gridfs', gfs);
console.log('all set');
});
//POST http://localhost:3000/file
app.post('/file', function (req, res) {
var gridfs = app.get('gridfs');
var writeStream = gridfs.createWriteStream({
filename: 'file_name_here'
});
writeStream.on('close', function (file) {
res.send(`File has been uploaded ${file._id}`);
});
req.pipe(writeStream);
});
//GET http://localhost:3000/file/[mongo_id_of_file_here]
app.get('/file/:fileId', function (req, res) {
var gridfs = app.get('gridfs');
gridfs.createReadStream({
_id: req.params.fileId // or provide filename: 'file_name_here'
}).pipe(res);
});
app.listen(process.env.PORT || 3000);

Querying MongDB database using NodeJS and jQuery

I am stuck trying to query my database built using MongoDB (with Mongoose as the ODM) and displaying the results on the page. The database stores the data (comprising of date: 'date', and link: 'wwww.example.com') in a collection I named 'entries'. I have two views that I want to use to access the database: a view which will utilize the date key to display the right link on a particular day; and a view of the database where I can view, add and delete entries. I was somehow able to loop through the entries for the database view and add them to the DOM but when I try the same for the widget view I can't seem to access the JSON object from the entries collection. I'm using Jade as a preprocessor for my HTML
My app.js file is like so:
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 router = express.Router();
//database stuff
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
//connect to the data store and the set up the database
var db = mongoose.connection;
//connect to the database
var conn = mongoose.connect('mongodb://localhost/Mandela_Diaries/data');
//Create a model which connects to the schema and entries collection in the Mandela_Diaries database
var Entry = mongoose.model("Entry", new Schema({date: 'date', link: 'string'}), "entries");
mongoose.connection.on("open", function() {
console.log("mongodb is connected!");
});
var routes = require('./models/index');
var users = require('./routes/users');
var database = require('./routes/database');
var methodOverride = require('method-override');
var templatemain = require('./routes/template-main');
var app = express();
// Methodoverride at the top
app.use(methodOverride('_method'));
// 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(__dirname + '/public/favicon.ico'));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
//serving static files
app.use('/public', express.static(__dirname + '/public'));
app.use('/public', express.static(__dirname + '/css'));
app.use('/public', express.static(__dirname + '/js'));
app.use('/public', express.static(__dirname + '/images'));
app.use('/public', express.static(__dirname + '/node_modules'));
app.use('/', routes);
app.use('/', routes);
app.use('/', routes);
app.use('/database', database);
app.use('/create', database);
app.use('/delete', database);
app.use('/:id', database);
// app.use('/database/#{entry._id}?/delete', database);
// 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;
module.exports.Entry = Entry;
app.listen(8080);
console.log("The server has started");
My database.js router code is like so:
var express = require('express');
var router = express.Router();
var mongoose = require('mongoose');
var Entry = mongoose.model('Entry');
//The route for getting data for the database - GET form
router.get("/", function(req, res) {
//Send the current entries to the page
Entry.find({}, function(err, entries) {
console.log(entries);
if(err) {
res.status(404).json({"error": "not found", "err":err});
return;
} else {
res.render('database', {title: 'database', entries: entries});
//console.log(entries);
//entries.forEach(printjson);
}
});
});
//The route for posting data to the database - POST
router.post('/', function(req, res) {
var newEntry = new Entry(req.body);
newEntry.save(function(err, entries){
if (err !== null) {
res.status(500).json(err);
} else {
res.redirect('database');
};
});
});
//The route for deleting data to the database - Delete/remove todo item by its id
// Changed path from `/` to `/:id`
router.delete('/:id', function (req, res) {
Entry.findById(req.params.id)
.exec(function(err, entries) {
// changed `if (err || !doc)` to `if (err || !entries)`
if (err || !entries) {
res.statusCode = 404;
res.send({});
} else {
entries.remove(function(err) {
if (err) {
res.statusCode = 403;
res.send(err);
} else {
res.send('Deleted entry with link: ', entries.link);
}
});
}
});
});
module.exports = router;
My index.js router code is like so:
var express = require('express');
var router = express.Router();
var mongoose = require('mongoose');
var Entry = mongoose.model('Entry');
var moment = require('moment');
/* GET home page. */
router.get('/', function(req, res, next) {
res.render('/', { title: 'Express' });
Entry.find({}, function(err, entries) {
if(err) {
res.status(404).json({"error": "not found", "err":err});
return;
} else {
res.render('/', {title: 'database', entries: entries});
}
});
});
console.log("new code works");
module.exports = router;
My script.js code running the jQuery to append the correct video links according to the date is like so:
$(document).ready(function() {
//Date picker jQuery
$(function() {
$( ".datepicker" ).datepicker();
$( "#format" ).change(function() {
$( ".datepicker" ).datepicker( "option", "dateFormat", $( this ).val() );
});
});
var browserDate = new Date();
var videoDate = new Date(1962);
//var month = browserDate.getMonth() + 1;
//var day = browserDate.getDate();
//var year = browserDate.getFullYear();
var context = browserDate - videoDate;
$('#context').innerHTML = "ON THIS DAY " + context + " YEARS AGO:";
console.log("ON THIS DAY " + context + " YEARS AGO:");
console.log("This worked!!");
console.log(browserDate);
});
And my Jade code for index.jade is like this:
extends layout
block content
#widget.container
.row
#header.col-xs-12.header
img#Mandela_Logo(src='/public/images/Logo_MandelaDiaries.png')
.row
#context.col-xs-12
.row
#videos.col-xs-12
.embed-responsive.embed-responsive-4by3
iframe(width='300', height='169', src='https://www.youtube.com/embed/4HqtAMHrJ8s', frameborder='0', allowfullscreen='')
.row
#footer.col-xs-12
img#NMF_logo(src='/public/images/Logo_NMF.png')
img#SABC_logo(src='/public/images/Logo_SABCNews.png')
I can't seem to be able to get my jQuery to work here. I just want to get the JSON object and loop through it and find the relevant day, based on the browser date, and attach the corresponding link to the iframe in my widget.

To simplify things, you could use the momentjs library which is great at dealing with dates. In your use case, you want to use the fromNow() method which displays the relative time from now, say for example
moment([2011, 0, 29]).fromNow(); // 4 years ago
moment("1962-04-08T09:48:16.189Z").fromNow() // 53 years ago
To use the momentjs library in your views, you need to add it to your express application locals as follows:
express = require('express');
...
var app = express();
app.locals.moment = require('moment');
Since you can use plain JavaScript code in in your Jade views, you can easily do:
extends layout
block content
#widget.container
.row
#header.col-xs-12.header
img#Mandela_Logo(src='/public/images/Logo_MandelaDiaries.png')
.row
#context.col-xs-12
each entry in entries
p= 'ON THIS DAY ' + moment(entry.date).fromNow() + ' - Link: ' + entry.link + ' '
.row
#videos.col-xs-12
.embed-responsive.embed-responsive-4by3
iframe(width='300', height='169', src='https://www.youtube.com/embed/4HqtAMHrJ8s', frameborder='0', allowfullscreen='')
.row
#footer.col-xs-12
img#NMF_logo(src='/public/images/Logo_NMF.png')
img#SABC_logo(src='/public/images/Logo_SABCNews.png')
Demo
Source: Making use of utility libraries in server-side Jade templates