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Node error handler bugs when using error pattern (err, req, res, next)

I am currently running node with the express middleware and handling request with the GET method. Errors like 404s or 500s are handled at the end of my script, after the GET method, but so far I have not been able to use Node's standard error handling method with err,req,res,next. The below code works fine for me. But ...
server.js
...
// Routing
app.use('/', function (req, res, next) {
req.const = {
nonce: nonce,
publicRoot: publicRoot,
client: client,
cachelifespan: cachelifespan
};
next();
}, router);
// Error handling
app.use('/', function (req, res, next) {
req.const = {
nonce: nonce,
publicRoot: publicRoot,
};
next();
}, errorHandler);
...
errorhandler.js:
...
errorHandler.use(function (req, res) {
let id = req.ip;
let url = req.url;
// Import
let nonce = req.const.nonce;
let publicRoot = req.const.publicRoot;
res.statusCode = 500;
let status = res.statusCode;
try {
let localPath = path.join(publicRoot, req.path);
fs.accessSync(localPath);
} catch (err) {
status = 404;
};
if (req.accepts('html')) {
try {
res.render('system/error', { title: status.toString(), description: 'This is an error!', nonce: 'nonceValue' }, function(err, html) {
html = html.replace("nonceValue", nonce);
res.send(html);
});
} catch (err) {
logError(id, status, req.url, err)
};
} else if (req.accepts('json')) {
res.send({ error: status.toString() });
} else {
res.type('txt').send("error: " + status.toString());
}
logError(id, status, req.url);
});
...
... if I try to write the app.use function to ...
app.use(function (err, req, res, next) {
... it bugs and Node's default error handler takes over.
I am not entirely sure how to fix that.
Or if I am doing the error handling right?
Any suggestions?

I found a solution to my problem.
Inside server.js (the main app js), I load the errorHandler in the beginning of the file:
const errorHandler = require('./errorhandler');
And in the last step, after the basic routing, I added the errorhandler:
// Routing
app.use('/', function (req, res, next) {
req.const = {
nonce: nonce,
publicRoot: publicRoot,
client: client,
cachelifespan: cachelifespan
};
next();
}, router);
// Error handling
app.use('/', function (req, res, next) {
req.const = {
nonce: nonce,
publicRoot: publicRoot,
};
next();
}, errorHandler);
Inside the separate errorhandler file:
//--------------------
// NODE
//--------------------
const express = require('express');
const errorHandler = express.Router();
//--------------------
// LOGGING
//--------------------
const { getDate, logOutput, logError } = require('./logger');
//--------------------
// ROUTER
//--------------------
errorHandler.use(function (req, res) {
let id = req.ip;
let url = req.url;
// Import
let nonce = req.const.nonce;
let publicRoot = req.const.publicRoot;
// Cookies
let insultor = "Samuel L Jackson says";
let insults = ['Motherfucker!!!', 'Son_of_a_bitch!!!', 'Asshole!!!', 'Punkass_motherfucker!!!', 'Whiny_little_bitch!!!', 'You_deserve_to_die_and_I_hope_you_burn_in_hell!!!', 'Web_motherfucker_do_you_speak_it?'];
let number = Math.floor(Math.random() * insults.length);
let insulted = false;
for (let [key, value] of Object.entries(req.cookies)) {
if (key.toString() == insultor) {
value = value.toString() + "_-_" + insults[number];
res.cookie(insultor, value);
insulted = true;
}
}
if (!insulted) {
res.cookie(insultor, insults[number]);
}
res.statusCode = 500;
let status = res.statusCode;
try {
let localPath = path.join(publicRoot, req.path);
fs.accessSync(localPath);
} catch (err) {
status = 404;
};
if (req.accepts('html')) {
try {
res.render('system/error', { title: status.toString(), description: 'This is an error, Motherfucker!', nonce: 'nonceValue' }, function(err, html) {
html = html.replace("nonceValue", nonce);
res.send(html);
});
} catch (err) {
logError(id, status, req.url, err)
};
} else if (req.accepts('json')) {
res.send({ error: status.toString() });
} else {
res.type('txt').send("error: " + status.toString());
}
logError(id, status, req.url);
});
module.exports = errorHandler;

How to merge two files API (Node.js)

I am a node.js and MySQL beginner and I just started setting up and trying out some basic code.
I find these two APIs to practice, one is the API for the CRUD database, and the other is the API for judging user login / registration.I tried to merge the APIs of these two files, and the result was a problem. I think the current problem is the configuration file (conf.js).I plan to write a function and then wrap any file and use it again, so that the configuration files may not conflict, but I don’t know how to start.
These are the two API teaching URLs I practiced
http://www.expertphp.in/article/user-login-and-registration-using-nodejs-and-mysql-with-example
https://www.footmark.info/programming-language/nodejs/nodejs-restful-webapi-mysql/
index.js
var express = require("express");
var bodyParser = require("body-parser");
var app = express();
var authenticateController = require("./controllers/authenticate-controller");
var registerController = require("./controllers/register-controller");
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.post("/api/register", registerController.register);
app.post("/api/authenticate", authenticateController.authenticate);
app.listen(3000);
app.js
var bodyparser = require("body-parser");
var express = require("express");
var conf = require("./conf");
var functions = require("./functions");
var user = require("./routes/user");
var app = express();
req.body
app.use(bodyparser.urlencoded({ extended: false }));
app.use(bodyparser.json());
//app.use(functions.passwdCrypto);
app.use("/user", user);
app.listen(conf.port, function() {
console.log("app listening on port " + conf.port + "!");
});
authenticate-controller.js
var connection = require('./../conf');
module.exports.authenticate=function(req,res){
var email=req.body.email;
var password=req.body.password;
connection.query('SELECT * FROM user WHERE email = ?',[email], function (error, results, fields) {
if (error) {
res.json({
status:false,
message:'there are some error with query'
})
}else{
if(results.length >0){
if(password==results[0].password){
res.json({
status:true,
message:'successfully authenticated'
})
}else{
res.json({
status:false,
message:"Email and password does not match"
});
}
}
else{
res.json({
status:false,
message:"Email does not exits"
});
}
}
});
}
register-controller.js
var connection = require('../conf');
module.exports.register=function(req,res){
var today = new Date();
var user={
"name":req.body.name,
"email":req.body.email,
"password":req.body.password,
"created_at":today,
"updated_at":today
}
connection.query('INSERT INTO user SET ?',user, function (error, results, fields) {
if (error) {
res.json({
status:false,
message:'there are some error with query'
})
}else{
res.json({
status:true,
data:results,
message:'user registered sucessfully'
})
}
});
}
user.js(models)
var mysql = require("mysql");
var conf = require("../conf");
var connection = mysql.createConnection(conf.db);
var sql = "";
module.exports = {
items: function(req, callback) {
sql = "SELECT * FROM user";
return connection.query(sql, callback);
},
item: function(req, callback) {
sql = mysql.format("SELECT * FROM user WHERE userId = ?", [req.params.id]);
return connection.query(sql, callback);
},
add: function(req, callback) {
sql = mysql.format("INSERT INTO user SET ?", req.body);
return connection.query(sql, callback);
},
delete: function(req, callback) {
sql = mysql.format("DELETE FROM user WHERE userId = ?", [req.params.id]);
return connection.query(sql, callback);
},
put: function(req, callback) {
connection.beginTransaction(function(err) {
if (err) throw err;
sql = mysql.format("DELETE FROM user WHERE userId = ?", [req.params.id]);
connection.query(sql, function(err, results, fields) {
if (results.affectedRows) {
req.body.id = req.params.id;
sql = mysql.format("INSERT INTO user SET ?", req.body);
connection.query(sql, function(err, results, fields) {
if (err) {
connection.rollback(function() {
callback(err, 400);
});
} else {
connection.commit(function(err) {
if (err) callback(err, 400);
callback(err, 200);
});
}
});
} else {
callback(err, 410);
}
});
});
},
patch: function(req, callback) {
sql = mysql.format("UPDATE user SET ? WHERE userId = ?", [req.body, req.params.id]);
return connection.query(sql, callback);
}
};
user.js(routes)
var express = require("express");
var user = require("../models/user");
var router = express.Router();
router
.route("/")
.get(function(req, res) {
user.items(req, function(err, results, fields) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
if (!results.length) {
res.sendStatus(404);
return;
}
res.json(results);
});
})
.post(function(req, res) {
user.add(req, function(err, results, fields) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
res.status(201).json(results.insertId);
});
});
router
.route("/:id")
.get(function(req, res) {
user.item(req, function(err, results, fields) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
if (!results.length) {
res.sendStatus(404);
return;
}
res.json(results);
});
})
.delete(function(req, res) {
user.delete(req, function(err, results, fields) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
if (!results.affectedRows) {
res.sendStatus(410);
return;
}
res.sendStatus(204);
});
})
.put(function(req, res) {
user.put(req, function(err, results) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
if (results === 410) {
res.sendStatus(410);
return;
}
user.item(req, function(err, results, fields) {
res.json(results);
});
});
})
.patch(function(req, res) {
user.patch(req, function(err, results, fields) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
if (!results.affectedRows) {
res.sendStatus(410);
return;
}
req.body.id = req.params.id;
res.json([req.body]);
});
});
module.exports = router;
conf.js
var mysql = require("mysql");
var connection = mysql.createConnection({
host: "localhost",
user: "root",
password: "1234",
database: "farmbot",
});
connection.connect(function(err) {
if (!err) {
console.log("Database is connected");
} else {
console.log("Error while connecting with database");
}
});
module.exports = connection;
/*If I comment out the code below, I can execute the login / register API*/
/*Without commenting out, can only perform CRUD on the database*/
module.exports = {
db: {
host: "localhost",
user: "root",
password: "1234",
database: "farmbot"
},
port: 3000
};

You will have to refactor them properly. You will need only once file to begin with. Why using it twice?
Refactor them in one file instead of listening to them on different ports. Once done, you can show the code to us so that we can fix it further if there's an issue.
Start from index.js and merge app.js with it but a bit carefully. I think doing it by yourself you will learn much from it.

Why the server not accessing connection variable?

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'
});
}

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) { ...

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
});
});
}
});
};

Node & Mongo db.open giving undefined is not a function

Following this tutorial, when running my server.js file I am getting the following error
self.s.pool = new Pool(Object.^assign(self.s.options, options, {bson:this.s.
TypeError: undefined is not a function
"
Seems to be a problem with my db.open() function. However, I am unsure as to whether it is because a connection can not be made to the database or something else.
I can log the server and db objects, so not sure where the undefined error is coming from. It doesn't log the error message contained in the db.open function so something seems to break before then.
Any help would be great, below is my code
server.js
var express = require('express'),
movies = require('./routes/movies.js');
var app = express();
app.configure(function(){
app.use(express.logger('dev'));
app.use(express.bodyParser());
});
app.get('/movies',movies.findAll);
app.get('/movies/:id',movies.findById);
app.post('/movies', movies.addMovie);
app.put('/movies/:id',movies.updateMovie);
app.delete('/movies/:id',movies.deleteMovie);
app.listen(3000);
console.log('Listening on port 3000...');
routes/movies.js
var mongo = require('mongodb');
var Server = mongo.Server,
Db = mongo.Db,
BSON = mongo.BSONPure;
var server = new Server('localhost', 27017, {auto_reconnect: true});
db = new Db('moviedb', server);
db.open(function(err,db){
if(!err)
{
console.log('Connected to "moviesdb" database');
db.collection('movies',{strict:true},function(err,collection){
if(err)
{
console.log("The 'movies' collection doesn't exist. Creating it with sample data...");
populateDB();
}
});
}
});
exports.findAll = function(req,res){
db.collection('movies',function(err,collection){
collection.find().toArray(function(err,items){
res.send(items);
});
});
}
exports.findById = function(req,res){
var id = req.params.id;
console.log('Retrieving movie: ' + id);
db.collection('movies',function(err,collection){
collection.findOne({'_id':new BSON.ObjectID(id)}, function(err,item){
res.send(item);
});
});
}
exports.addMovie = function(req,res){
var movie = req.body;
console.log('Adding movie: ' + JSON.stringify(movie));
db.collection('movies',function(err,collection){
collection.insert(movie,{'safe':true},function(err,result){
if(err)
{
res.send({'error':'An error has occurred'});
}
else
{
console.log('Success:' + JSON.stringify(result[0]));
res.send(result[0]);
}
});
});
}
exports.updateMovie = function(req,res){
var id = req.params.id,
movie = req.body;
console.log('Updating movie: ' + id);
console.log(JSON.stringify(movie));
db.collection('movies',function(err,collection){
collection.update({'_id':new BSON.ObjectID(id)},movie,{'safe':true},function(err,result){
if(err)
{
console.log('Error updating movie: ' + err);
res.send({'error':'An error has occured'});
}
else
{
console.log('' + result + ' document(s) updated');
res.send(movie);
}
});
});
}
exports.deleteMovie = function(req,res){
var id = req.params.id;
console.log('Deleting movie: ' + id);
db.collection('movies',function(err,collection){
collection.remove({'_id':new BSON.ObjectID(id)}, {safe:true}, function(err, result) {
if(err)
{
res.send({'error':'An error has occurred - ' + err});
}
else
{
console.log('' + result + ' document(s) deleted');
res.send(req.body);
}
});
});
}
/*--------------------------------------------------------------------------------------------------------------------*/
// Populate database with sample data -- Only used once: the first time the application is started.
var populateDB = function() {
var movies = [
{
name: "Titanic",
release: "2009",
description: "description....",
picture: "titanic-poster.jpg"
},
{
name: "Jaws",
release: "2000",
description: "description....",
picture: "jaws-poster.jpg"
},
{
name: "Halloween",
release: "1992",
description: "description....",
picture: "halloween-poster.jpg"
}
];
db.collection('movies', function(err, collection) {
collection.insert(movies, {safe:true}, function(err, result) {});
});
}

Issue with express search function

So I am working on an api for a todo app, and I have my 4 basic functions implemented but I'm trying to implement a search function. It worked the first time I tested it, but now every time I attempt to use it I am returning the same task no matter what my query is. Any help would be great. Also my search function is in my app.js file because I couldn't get it to function properly in my tasks.js file.
App.js
var express = require('express'),
routes = require('./routes'),
http = require('http'),
tasks = require('./routes/tasks'),
mongoose = require('mongoose'),
task = require('./routes/search');
var Task = require('./models/task').Task;
// MongoDB Connection
mongoose.connect('mongodb://localhost/task_tracker');
var app = express();
app.configure(function() {
app.set('port', 3000);
app.set('views', __dirname + '/views');
app.set('view engine', 'jade');
app.use(express.favicon());
app.use(express.logger('dev'));
app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(app.router);
app.use(express.urlencoded());
app.use(express.json());
});
app.use(function(req, res, next) {
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
next();
});
app.get('/', routes.index);
app.get('/tasks', tasks.index);
//app.get('/search', tasks.FindByQuery);
//app.get('/tasks/:task.:name?', task.FindByQuery);
app.get('/search', function(req, res) {
var query = req.query
//res.send(query['name']);
Task.findOne(query['name'], function(err, doc) {
if(!err && doc) {
res.json(200, doc);
} else if(err) {
res.json(500, { message: "Error loading task." + err});
} else {
res.json(404, { message: "Task not found."});
}
});
//res.end(JSON.stringify(query));
});
app.get('/tasks/:id', tasks.show);
app.post('/tasks', tasks.create);
app.put('/tasks', tasks.update);
app.del('/tasks', tasks.delete);
http.createServer(app).listen(app.get('port'), function() {
console.log("Express server listening on port 3000");
});
Tasks.js
var Task = require('../models/task').Task;
/*
* Tasks Routes
*/
exports.index = function(req, res) {
Task.find({}, function(err, docs) {
if(!err) {
res.json(200, { tasks: docs });
} else {
res.json(500, { message: err });
}
});
}
exports.show = function(req, res) {
var id = req.params.id;
Task.findById(id, function(err, doc) {
if(!err && doc) {
res.json(200, doc);
} else if(err) {
res.json(500, { message: "Error loading task." + err});
} else {
res.json(404, { message: "Task not found."});
}
});
}
exports.create = function(req, res) {
var task_name = req.body.task_name; // Name of task.
var description = req.body.task_description; // Description of the task
//Task.findOne({ name: task_name }, function(err, doc) { // This line is case sensitive.
Task.findOne({ name: { $regex: new RegExp(task_name, "i") } }, function(err, doc) { // Using RegEx - search is case insensitive
if(!err && !doc) {
var newTask = new Task();
newTask.name = task_name;
newTask.description = description;
newTask.save(function(err) {
if(!err) {
res.json(201, {message: "Task created with name: " + newTask.name });
} else {
res.json(500, {message: "Could not create task. Error: " + err});
}
});
} else if(!err) {
// User is trying to create a task with a name that already exists.
res.json(403, {message: "Task with that name already exists, please update instead of create or create a new task with a different name."});
} else {
res.json(500, { message: err});
}
});
}
exports.update = function(req, res) {
var id = req.body.id;
var task_name = req.body.task_name;
var task_description = req.body.task_description;
Task.findById(id, function(err, doc) {
if(!err && doc) {
doc.name = task_name;
doc.description = task_description;
doc.save(function(err) {
if(!err) {
res.json(200, {message: "Task updated: " + task_name});
} else {
res.json(500, {message: "Could not update task. " + err});
}
});
} else if(!err) {
res.json(404, { message: "Could not find task."});
} else {
res.json(500, { message: "Could not update task." + err});
}
});
}
exports.delete = function(req, res) {
var id = req.body.id;
Task.findById(id, function(err, doc) {
if(!err && doc) {
doc.remove();
res.json(200, { message: "Task removed."});
} else if(!err) {
res.json(404, { message: "Could not find task."});
} else {
res.json(403, {message: "Could not delete task. " + err });
}
});
}
search.js
var Task = require('../models/task').Task;
exports.FindByQuery = function(req, res) {
var query = req.query
//res.send(query['name']);
Task.findOne(query['name'], function(err, doc) {
if(!err && doc) {
res.json(200, doc);
} else if(err) {
res.json(500, { message: "Error loading task." + err});
} else {
res.json(404, { message: "Task not found."});
}
});
//res.end(JSON.stringify(query));
});
task.js
var mongoose = require('mongoose')
, Schema = mongoose.Schema;
var taskSchema = new Schema({
name : { type: String, required: true, trim: true, index: { unique: true } }
, description : { type: String, required: true }
, date_created : { type: Date, required: true, default: Date.now }
});
var task = mongoose.model('task', taskSchema);
module.exports = {
Task: task
};

I ended up figuring it out I just had to change my function a little bit. My error was in the format of my findOne function.
app.get('/search', function(req, res) {
var query = req.query
//res.send(query['name']);
Task.findOne({name: query['name']}, function(err, doc) {
if(!err && doc) {
res.json(200, doc);
} else if(err) {
res.json(500, { message: "Error loading task." + err});
} else {
res.json(404, { message: "Task not found."});
}
});
//res.end(JSON.stringify(query));
});