Mongodb nodejs Check if exists - node.js

Question

i'm trying to make an api which stores products and users!
at this time i want to make sure that the product which will be posted each has a unique Serial number and the code that will allow to have the same name, but i encouter the following error!
> TypeError: db.collection.find is not a function <br> at
> Object.module.exports.saveProductsignup
> (/home/themis/firstapp/api/config/database.js:14:19) <br>
> at /home/themis/firstapp/api/server.js:103:21 <br>
> at Layer.handle [as handle_request]
> (/home/themis/firstapp/api/node_modules/express/lib/router/layer.js:82:5)
> <br> at next
> (/home/themis/firstapp/api/node_modules/express/lib/router/route.js:100:13)
> <br> at Route.dispatch
> (/home/themis/firstapp/api/node_modules/express/lib/router/route.js:81:3)
> <br> at Layer.handle [as handle_request]
> (/home/themis/firstapp/api/node_modules/express/lib/router/layer.js:82:5)
> <br> at
> /home/themis/firstapp/api/node_modules/express/lib/router/index.js:234:24
> <br> at Function.proto.process_params
> (/home/themis/firstapp/api/node_modules/express/lib/router/index.js:312:12)
> <br> at
> /home/themis/firstapp/api/node_modules/express/lib/router/index.js:228:12
> <br> at Function.match_layer
> (/home/themis/firstapp/api/node_modules/express/lib/router/index.js:295:3)
> <br> at next
> (/home/themis/firstapp/api/node_modules/express/lib/router/index.js:189:10)
> <br> at
> /home/themis/firstapp/api/node_modules/express/lib/router/index.js:191:16
> <br> at Function.match_layer
> (/home/themis/firstapp/api/node_modules/express/lib/router/index.js:295:3)
> <br> at next
> (/home/themis/firstapp/api/node_modules/express/lib/router/index.js:189:10)
> <br> at
> /home/themis/firstapp/api/node_modules/express/lib/router/index.js:191:16
> <br> at Function.match_layer
> (/home/themis/firstapp/api/node_modules/express/lib/router/index.js:295:3)
server.js
var express = require('express'),
MongoClient = require('mongodb').MongoClient,
app = express(),
mongoUrl= 'mongodb://localhost:27017/firstapp';
var access = require('./config/database.js');
var assert = require('assert');
var ObjectId = require('mongodb').ObjectID;
var bodyParser = require('body-parser');
var morgan = require('morgan');
var mongoose = require('mongoose');
var passport = require('passport');
var redisClient = require('redis').createClient;
var redis = redisClient(6379, 'localhost');
var config = require('./config/database'); // get db config file
var User = require('./app/models/user'); // get the mongoose model
var port = process.env.PORT || 8080;
var jwt = require('jwt-simple');
// get our request parameters
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
// log to console
app.use(morgan('dev'));
// Use the passport package in our application
app.use(passport.initialize());
// demo Route (GET http://localhost:8080)
app.get('/', function(req, res) {
res.send('The API is at http://localhost:' + port + '/api');
});
// connect to database
mongoose.connect(config.database);
// pass passport for configuration
require('./config/passport')(passport);
// bundle our routes
var apiRoutes = express.Router();
MongoClient.connect(mongoUrl, function(err, db) {
if (err) throw 'Error connecting to database - ' + err;
// create a new user account (POST http://localhost:8080/api/signup)
apiRoutes.post('/signup', function(req, res) {
if (!req.body.name || !req.body.password || !req.body.email) {
res.json({success: false, msg: 'Please pass name and password and email.'});
} else {
var newUser = new User({
name: req.body.name,
password: req.body.password,
email: req.body.email
});
// save the user
newUser.save(function(err) {
if (err) {
return res.json({success: false, msg: 'Username already exists.'});
}
res.json({success: true, msg: 'Successful created new user.'});
});
}
});
//User authentication (POST http://localhost:8080/api/authenticate)
apiRoutes.post('/authenticate', function(req, res) {
User.findOne({
name: req.body.name
}, function(err, user) {
if (err) throw err;
if (!user) {
res.send({success: false, msg: 'Authentication failed. User not found.'});
} else {
// check if password matches
user.comparePassword(req.body.password, function (err, isMatch) {
if (isMatch && !err) {
// if user is found and password is right create a token
var token = jwt.encode(user, config.secret);
// return the information including token as JSON
res.json({success: true, token: 'JWT ' + token});
} else {
res.send({success: false, msg: 'Authentication failed. Wrong password.'});
}
});
}
});
});
//create posts about product (POST http://localhost:8080/api/createpost)
apiRoutes.post('/resources/createpost', function (req, res) {
if (!req.body.issue || !req.body.SN) res.status(400).send("Please give an issue and a S/N for the product");
else {
access.savePost(db, req.body.issue, req.body.SN, function (err) {
if (err) res.status(500).send("Server error");
else res.status(201).send("Post Created");
});
}
});
apiRoutes.post('/resources/productsignup', function (req, res) {
if (!req.body.name || !req.body.serialnumber) res.status(400).send("Please give a name and a Serial number for the product");
else {
access.saveProductsignup(db, req.body.name, req.body.serialnumber, function (err) {
if (err) res.status(500).send("Server error");
else res.status(201).send("Post Created");
});
}
});
//restricted log in (GET http://localhost:8080/api/memberinfo)
apiRoutes.get('/memberinfo', passport.authenticate('jwt', { session: false}), function(req, res) {
var token = getToken(req.headers);
if (token) {
var decoded = jwt.decode(token, config.secret);
User.findOne({
name: decoded.name
}, function(err, user) {
if (err) throw err;
if (!user) {
return res.status(403).send({success: false, msg: 'Authentication failed. User not found.'});
} else {
res.json({success: true, msg: 'Welcome in the member area ' + user.name + '!'});
}
});
} else {
return res.status(403).send({success: false, msg: 'No token provided.'});
}
});
getToken = function (headers) {
if (headers && headers.authorization) {
var parted = headers.authorization.split(' ');
if (parted.length === 2) {
return parted[1];
} else {
return null;
}
} else {
return null;
}
};
//demo Start
apiRoutes.delete('/resources/productinfo/:id', function(req, res, next) {
Products.findByIdAndRemove(req.params.id, req.body, function(err, post){
if (err) return next(err);
res.json(post);
});
});
apiRoutes.get('/productinfo' , function(req, res, next) {
Products.find( function (err, result) {
if (err) return console.error(err);
res.json(result);
});
});
apiRoutes.get('/resources/productinfo/:name' , function(req, res) {
if (!req.param('name')) res.status(400).send("Please send a proper name");
else{
access.findProductsByName(db, req.param('name'), function(info) {
if (!products) res.status(500).send("server error");
else res.status(200).send(info);
});
}
});
//demo End
// connect the api routes under /api/*
app.use('/api', apiRoutes);
module.exports = apiRoutes;
app.listen(8080, function() {
console.log('listening on port 8080');
});
});
database.js
module.exports = {
'secret': 'di.ionio.gr',
'database': 'mongodb://localhost/firstapp'
};
module.exports.savePost = function (db, issue, SN, callback) {
db.collection('posts').save({
issue: issue,
SN: SN
}, callback);
};
module.exports.saveProductsignup = function (db, name, serialnumber, callback) {
db.collection.find({ "serialnumber" : { $exists : true, $ne : null } })
db.collection('products').save({
name: name,
serialnumber: serialnumber
}, callback);
};
module.exports.findProductsByName = function (model, name, callback) {
model.findOne({
name: name
}, function (err, doc) {
if (err || !doc) callback(null);
else callback(doc.products);
});
};

Answer 1

You have a typo in database.js in module.exports.saveProductsignup:
db.collection.find({ "serialnumber" : { $exists : true, $ne : null } })
Should be:
db.collection('products').find({ "serialnumber" : { $exists : true, $ne : null } })