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app.get() is not working. related to Difference between app.use and app.get in express.js

var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');
var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');
var app = express();
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');
app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', indexRouter);
app.use('/users', usersRouter);
module.exports = app;
I created express-generator. Then I tried to change app.use('/', indexRouter) → app.get('/', indexRouter) and app.use('/users', usersRouter) → app.get('/users', usersRouter).
Then app.get('/', indexRouter) was working(can hit the URL and get the page information). But app.get('/users', usersRouter) was NOT working. This returned 404 (NotFoundError: Not Found).
I already read this questionDifference between app.use and app.get in express.js
But I couldn't understand
./routes/index.js
var express = require('express');
var router = express.Router();
/* GET home page. */
router.get('/', function(req, res, next) {
res.render('index', { title: 'Express' });
});
module.exports = router;
./routes/users
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;

app.use is designed for middlewares and app.get is designed for GET requests. Middlewares are functions that are called before the controller. You may have a middleware to check if the user is authenticate or not, and accept the user's request or deny it.
When you have app.use('/', indexRouter), the indexRouter will be called for all your requests on all your routes. It is like /*.
When you have app.use('/users', usersRouter), the usersRouter will be called for all your requests on all routes that start with /users. It is like /users*.
This is how you can do a GET request:
app.get('/users', (req, res) => res.status(200).send({
message: 'It works.',
}));

Cannot GET with nodejs?

I have a simple nodejs app with some users. I want to load a specific user profile using a URL localhost/users/(username) but I'm getting this error when I try to load the URL:
Cannot GET /users/test
Here's my user.js routes file for the user page:
var express = require('express');
var router = express.Router();
var User = require('../models/user');
// GET user by username
router.get('/users/:username', function(req, res) {
var username = req.params.username;
res.send(req.params);
res.render('user');
});
module.exports = router;
I have a user.handlebars file in my views folder so it should load the file. What am I missing in my routes file? Any help would be greatly appreciated. Thanks!!
EDIT: app.js:
console.log('Starting app.js');
const fs = require('fs');
const _ = require('lodash');
const express = require('express');
const path = require('path');
const cookieParser = require('cookie-parser');
const bodyParser = require('body-parser');
const exphbs = require('express-handlebars');
const expressValidator = require('express-validator');
const flash = require('connect-flash');
const session = require('express-session');
const passport = require('passport');
const LocalStrategy = require('passport-local').Strategy;
const mongo = require('mongodb');
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/tipcup');
var db = mongoose.connection;
const routes = require('./routes/index');
const users = require('./routes/users');
const user = require('./routes/user');
// Init App
var app = express();
// View Engine
app.set('views', path.join(__dirname, 'views'));
app.engine('handlebars', exphbs({defaultLayout: 'layout'}));
app.set('view engine', 'handlebars');
// BodyParser middleware
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false}));
app.use(cookieParser());
// Set Static Folder
app.use(express.static(path.join(__dirname, 'public')));
// Express Session
app.use(session({
secret: 'secret',
saveUninitialized: true,
resave: true
}));
// Passport Init
app.use(passport.initialize());
app.use(passport.session());
// Express Validator
app.use(expressValidator ({
errorFormatter: function(param, msg, value) {
var namespace = param.split('.')
, root = namespace.shift()
, formParam = root;
while(namespace.length){
formParam += '[' + namespace.shift() + ']';
}
return {
param: formParam,
msg: msg,
value: value
};
}
}));
// Connect Flash
app.use(flash());
// Global Vars
app.use(function (req, res, next){
res.locals.success_msg = req.flash('success_msg');
res.locals.error_msg = req.flash('error_msg');
res.locals.error = req.flash('error');
res.locals.user = req.user || null;
next();
});
app.use('/', routes);
app.use('/users', users);
app.use('/users/:username', user);
// Set Port
app.set('port', (process.env.PORT || 3000));
app.listen(app.get('port'), function(){
console.log('Server started on port '+app.get('port'));
});

Render function renders a view and sends the rendered HTML string to the client.Take a look at documentation.
But what you are trying to archive is to send data first and then render and send again. So, just delete the line with send.
router.get('/users/:username', function(req, res) {
var username = req.params.username;
res.render('user');
});
And, please, edit your question by adding your code with middleware and add your error.
Update
Take a look at the way how you define your routes for users.
You have to remove /users from defining route in users.js file

Node js not returning proper result?

I have this node js program which should return asked variable in the console but it is returning undefined here is code and the input i have trying to parse :-
router.post('/createorder',function(req,res){
console.log(req.body.ProductName);
// var obj=JSON.parse(req.body);
res.send(req.body);
});
the input :
{
"ProductName":"Wine",
"ProductPrice":"500",
"ProductQuantity":"2",
"ProductCost":"1000",
"SellerId":"2"
}
and here is the main module i'm using
var express= require('express');
var routes=require('./routes/api');
var bodyparser=require('body-parser');
var mysql = require('mysql');
var db=mysql.createConnection({
host:'localhost',
user:'root',
password:'',
database:'nodemysql'
})
//setting up express
var app = express();
app.use(bodyparser.urlencoded({extended:false}));
app.use(bodyparser.json());
app.use(routes);
//listen for requests
/*app.get('/',function(req,res){
console.log('get trial method called');
res.send({name:'Atul'});
});*/
app.listen(3000,function(){
console.log('server started on port 3000 ');
});
i want to acess an specific object in order to store in the database?

As soueuls mentioned in the comments, you need to make sure express can parse the body of the request as it doesn't do this by default. Assuming you are using express framework. You could have something like this.
var express = require('express')
var bodyParser = require('body-parser')
var app = express()
// parse application/x-www-form-urlencoded
app.use(bodyParser.urlencoded({ extended: false }))
// parse application/json
app.use(bodyParser.json())
Now you can read the body.
notice if you console log your req object before you add in the code above, you will not see the body property.
UPDATE
this is what i have in 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 index = require('./routes/index');
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('/', 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;
In my routes/index.js i have the following
var express = require('express');
var router = express.Router();
router.post('/createorder',function(req,res){
console.log(req.body);
// var obj=JSON.parse(req.body);
res.send(req.body);
});
module.exports = router;
i tested this with postman app and it works.

How to use express middleware to handle all routes?

I have issue setting up routes for user in below code, I want to use express middleware and trying routes using app.use.
index.js is invoking user controller method once api's is being called So in below code i am trying to post data api/users from client but it returns 404.
How can i fix this issue using below routes setup ?
server.js
var express = require('express');
var app = express();
var bodyParser = require('body-parser');
var methodOverride = require('method-override');
var mongoose = require('mongoose');
console.log(mongoose.connection.readyState);
var db = require('./config/db');
var port = process.env.PORT || 8080;
mongoose.connect(db.url);
app.use(methodOverride('X-HTTP-Method-Override'));
app.use(express.static(__dirname + '/public'));
require('./app/routes')(app); // configure our routes
require('./config/express')(app);
app.listen(port);
console.log('listening on port ' + port);
exports = module.exports = app;
app > routes.js
module.exports = function(app) {
app.use('api/users', require('./api/user'));
app.get('*', function(req, res) {
res.sendfile('./public/views/index.html'); // load our public/index.html file
// res.sendFile(path.join(__dirname, ''../public/views/index.html''));
});
};
config > express.js
var express = require('express');
var morgan = require('morgan');
var bodyParser = require('body-parser');
// import cookieParser from 'cookie-parser';
// import errorHandler from 'errorhandler';
var path = require('path');
// import lusca from 'lusca';
var config = require('./db');
var mongoose = require('mongoose');
//var mongoStore = connectMongo(session);
module.exports = function(app) {
// app.engine('html', require('ejs').renderFile);
app.set('view engine', 'html');
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
app.use(methodOverride());
}
User index where i will handle all crud operation for user
app > api > user > index.js
var express = require('express');
var controller = require('./user.controller');
var router = express.Router();
router.get('/', controller.index);
router.post('/',controller.create);
module.exports = router;

1st:
To handle all request
Bind application-level middleware to an instance of the app object by using the app.use() and app.METHOD() functions, where METHOD is the HTTP method of the request that the middleware function handles (such as GET, PUT, or POST) in lowercase.
This example shows a middleware function with no mount path. The function is executed every time the app receives a request.
app.use(function(req,res)
{
res.sendfile('./public/views/index.html');
console.log("Not found....I will handle *unhandle* rout here for you");
})
// app.get('*', function(req, res) use the above function instead of this
But this function at the end so it will only excute when no route path found to the app object.
Express documentation
2nd:
To handle createuser
var express = require('express');
var controller = require('./user.controller');
var router = express.Router();
// you must define route which you want to handle in user file
router.get('/api/user', controller.index);
router.post('/',controller.create);
module.exports = router;
Update working example with some explanation
Your app.js file
var express=require('express')
var app=express()
app.use('api/user',require('./user'))
app.use('/',require('./user'))
app.use(function(req,res)
{
res.sendfile('stack10.html')
console.log("Not found....I will handle *unhandle* rout here for you");
})
app.listen(8080,function()
{
console.log("server listening on port 8080")
})
user.js
var express = require('express')
var router = express.Router()
var app=express()
router.get('/api/user', function(req, res) {
res.send('respond for ..../api/user')
});
router.get('/',function (req,res) {
res.send('respose for ..../')
})
module.exports = router;
Your app.use will be app.use(api/user) while in user will be router.get(/api/user) so when u try http://127.0.0.1:8080/api/user
your response will be respond for ..../api/user

Creating a working form in ExpressJS

I am new to NodeJS and ExpressJS development (a week old or so). I am trying to create a web application in NodeJS using ExpressJS framework. One of the things I am trying to do is build a registration form for my app. I have installed body-parser middleware using the npm to read form data.
I am using HoganJS as my template framework. I have a page in my views folder named register.hjs. This page has a form
<form method="post">
<input type="text" name="name">
<input type="text" name="age">
<input type="submit">
</form>
I am struggling with these two issues:
How to read form values in the .js
How to redirect a user to a different page once form is submitted.
This is what I am trying to do (it might be incorrect though).
In my app.js
//get
app.get('/register', routes.register);
//post
app.post('/welcome', routes.welcome);
In my index.js
/* GET about page.*/
exports.register = function(req, res) {
res.render('register');
};
/*POST registered user*/
exports.welcome = function(req, res) {
// pull the form variables off the request body
var name = req.body.name;
var age = req.body.age;
//just to make sure the information was read
console.log(name);
console.log(age);
res.render('welcome');
};
I am pretty sure I am missing something cause when I run my server it gives an error saying :
Error: Route.get() requires callback functions but got a [object Undefined]
What am I doing wrong? Is there any elegant way to read form data and redirect users to different pages?
Thanks.
--------------------------- Update ----------------------------
Here is the rest of the app.js Code
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');
//routes to the pages
var routes = require('./routes/index');
var users = require('./routes/users');
var register = require('./routes/register');
var app = express();
// view engine setup
app.set('views', path.join(__dirname, 'views')); //app.set('the name of your view folder', )
app.set('view engine', 'hjs');
//get
app.get('/register', routes.register);
//post
app.post('/welcome', routes.welcome);
// 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(express.static(path.join(__dirname, 'public')));
app.use('/', routes);
app.use('/users', users);
app.use('/register', register);
//error handlers
//error handlers
module.exports = app;

For Simple understanding how express works for form understand this code :
After understanding this code , use router and other body parser configuration---
var express = require('express');
/*
* body-parser is a piece of express middleware that
* reads a form's input and stores it as a javascript
* object accessible through `req.body`
*
* 'body-parser' must be installed (via `npm install --save body-parser`)
* For more info see: https://github.com/expressjs/body-parser
*/
var bodyParser = require('body-parser');
// create our app
var app = express();
// instruct the app to use the `bodyParser()` middleware for all routes
app.use(bodyParser());
// A browser's default method is 'GET', so this
// is the route that express uses when we visit
// our site initially.
app.get('/', function(req, res){
// The form's action is '/' and its method is 'POST',
// so the `app.post('/', ...` route will receive the
// result of our form
var html = '<form action="/" method="post">' +
'Enter your name:' +
'<input type="text" name="userName" placeholder="..." />' +
'<br>' +
'<button type="submit">Submit</button>' +
'</form>';
res.send(html);
});
// This route receives the posted form.
// As explained above, usage of 'body-parser' means
// that `req.body` will be filled in with the form elements
app.post('/', function(req, res){
var userName = req.body.userName;
var html = 'Hello: ' + userName + '.<br>' +
'Try again.';
res.send(html);
});
app.listen(80);

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 routes = require('./routes/index');
var app = express();
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'hjs');
// 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(express.static(path.join(__dirname, 'public')));
app.use('/', routes);
module.exports = app;
index.js:
var express = require('express');
var router = express.Router();
/* GET home page. */
router.get('/register', function(req, res) {
res.render('register');
});
router.post('/welcome', function(req, res) {
console.log(req.body.name);
console.log(req.body.age);
});
module.exports = router;