In below example for GET /api/users/i request secondMw is never executed even there is a next() call in firstMw. Why is that? How am I supposed to be able to run the secondMw?
var apiRouter = require('express').Router();
apiRouter.param('user', function firstMw(req, res, next, param) {
if(param === 'i'){
return next(); //jump to next mw sub-stack
}
next('route'); //continue with another matching route
}, function secondMw(req, res, next, param) {
console.log('NO, I AM NOT HERE. NEVER');
next();
});
apiRouter.get('/users/:user', function (req, res, next) {
res.json({
id: req.params.user
});
});
app.use('/api', apiRouter);
I don't see that router.params supports middleware stack (compare definition with app.get). But you can use ordered definition for same route.
'use strict';
let express = require('express');
let app = express();
app.use(require('body-parser').urlencoded({extended: false}));
var apiRouter = express.Router();
apiRouter.param('user', function mw1(req, res, next, param) {
console.log('MW1', param);
if (param === 'i')
next();
else
next('Error message'); // better next( new Error('Error message'));
});
apiRouter.param('user', function mw2(req, res, next, param) {
console.log('MW2', param);
next();
})
// If next() have params then Express calls handler error
apiRouter.use(function (err, req, res, next) {
console.log('Error: ', err)
res.send(err.message || err);
});
apiRouter.get('/users/:user', function (req, res, next) {
res.json({id: req.params.user});
});
app.use('/api', apiRouter);
app.listen(3000, function () {
console.log('Listening on port 3000');
});
Related
How to implement middleware like this in socket.io? Please help
EXPRESS APP
var myLogger = function (req, res, next) {
console.log('LOGGED')
next()
}
app.use(myLogger)
app.get('/', function (req, res) {
res.send('Hello World!')
})
SOCKET APP (I am using express pattern but its not working)
var myLogger = function (data,next) {
console.log('DOING DATA VALIDATION...')
next()
}
io.use(myLogger)
io.on('someEvent/', function (data, callback) {
callback('Hello World!')
})
Error : next() is not define!
app.use(function (req, res, next) {
req.io = io;
next();
});
This assigns a socket object to every request.
If somebody's still wondering.
To use middleware on all sockets:
io.use((socket, next) => {
// isValid is just a dummy function
if (isValid(socket.request)) {
next();
} else {
next(new Error("invalid"));
}
});
This example is from the official docs of socket.io
To use a middleware for a specific client:
io.on('connection', async (client) => {
client.use((socket, next) => {
console.log(`got event: ${socket[0]} in client middleware, moving on with next() just like in express`)
next()
});
// rest of your code
newConnection(client)
})
I am a beginner studying Nodejs.
I have recently studied node middleware and have created a simple game using middleware.
The purpose of the generated code is to respond to hello by connecting as root and then respond to the browser with 50% probability through the middleware.
However, I get the following error:
I did a search and found that res.send is not available after next ().
Is that correct?
But I could not figure out why and I did not realize why the code did not work.
code
const express = require('express');
var app = express();
app.use('/', (req, res, next) =>{
res.send('hello');
next();
});
app.use((req, res, next) => {
if (+new Date() % 2 === 0) {
console.log('continue');
res.send('lucky!');
next();
} else {
console.log('failed');
res.send('end');
}
});
app.use((req, res, next) => {
if (+new Date() % 2 === 0) {
console.log('continue');
res.send('lucky!');
next();
} else {
console.log('failed');
res.send('end');
}
});
app.listen(3000, () => console.log(`Example!`))
error
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
const express = require('express');
var app = express();
app.use(/^\/$/, (req, res, next) =>{
res.send('hello');
return;
});
app.use((req, res, next) => {
if (+new Date() % 2 === 0) {
console.log('continue');
res.send('lucky!');
next();
} else {
console.log('failed');
res.send('end');
}
});
app.listen(3000, () => console.log(`Example!`))
you cannot use res.send() twice
res.send() = Sends the HTTP response.
Here is the example:
var app = require('express')();
function validateToken(req, res, next) {
// Do something with request here
next();
};
app.get('/user/login', function(req, res) {
//code
});
app.post('/user/register', function(req, res) {
//code
})
app.put('/user/register', validateToken, function(req, res) {
//code
})
app.delete('/user/delete', validateToken, function(req, res) {
//code
})
If I have 10 api that need validToken, I should add validToken middleware 10 times, like:
app.method('......', validateToken, function(req, res) {
//code
})
app.method('......', validateToken, function(req, res) {
//code
})
....
app.method('......', validateToken, function(req, res) {
//code
})
app.method('......', validateToken, function(req, res) {
//code
})
How can I group api by using the same middleware?
Here's how to re-use the same callback function for multiple routes (like middleware):
var app = require('express')();
function validateToken(req, res, next) {
// Do something with request here
next();
};
app.get('/user/login', function(req, res) {
// code
});
app.post('/user/register', function(req, res) {
// code
});
// Be sure to specify the 'next' object when using more than one callback function.
app.put('/user/register', validateToken, function(req, res, next) {
// code
next();
});
app.delete('/user/delete', validateToken, function(req, res, next) {
// code
next();
});
Also, you can replace app.METHOD (e.g. .post, .get, .put, etc.) with app.all and your callback will be executed for any request type.
Just wrong, so do not put into mass participation of the (Google translated from: 刚才看错了，改成这样就不用放进传参了)
var group = {url:true,url:true,url:true};
app.use(function(req,res,next){
if(group[req.url]){
// Do something with request here
next();
} else {
next();
}
})
In a practice example, i'm trying to create a restfull API, very simple. The plain GET and POST methods works well, but the GET, PUT and DELETE method pointing to /api/bears/:bear_id just stay there, waiting...
// CONFIGURACION INICIAL //
// ===================== //
var express = require('express');
var app = express();
var bodyParser = require('body-parser');
var mongoose = require('mongoose');
var db = mongoose.connection;
// CONFIGURANDO APP //
// ================ //
app.use(bodyParser.urlencoded({ extended: true }))
app.use(bodyParser.json())
mongoose.connect('mongodb://localhost:27017/bears');
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function cb () {
console.log('conexion establecida');
})
var Bear = require('./models/bear_model.js');
var port = process.env.PORT || 8080; // seteo del puerto
var router = express.Router(); // instancia del ruteador
Above, the simple config, below, the snippet that is causing me problems:
router.use(function (req, res, next) { // simple logger
if (req.method === 'GET')
console.log('executing query on id %s', JSON.stringify(req.params));
else if (req.method === 'PUT')
console.log('executing query on id %s', JSON.stringify(req.params));
else
console.log('executing query on id %s', JSON.stringify(req.params));
});
router.route('/bears/:bear_id')
.get(function (req, res) {
Bear.findById(req.params.bear_id, function (err, bear) {
if (err)
res.send(err);
res.json(bear);
});
}) // end GET /bears/:bear_id
.put(function (req, res) {
Bear.findById(req.params.bear_id, function (err, bear) {
if (err)
res.send(err)
bear.name = req.body.name; // Update bear_id of Bear
bear.save(function (err) {
if (err)
res.send(err);
res.json({msg: 'Bear actualizado!'});
});
});
}) // end PUT /bears/:bear_id
.delete(function (req, res) {
Bear.remove({
_id: req.params.bear_id
}, function (err, bear) {
if (err)
res.send(err);
res.json({ msg: 'Bear eliminado' });
});
}); // end DELETE /bears/:id && router /bears/:id
app.use('/api', router); // la api usará como base el prefijo /api
Executing one route with a param log me: executing query on {}, so, the req.params.bear_id simply is not captured, and if i change req.params by req.params.bears_id, obviously i get an undefined log, so i read de docs and think i'm doing generally well the process but don't catch the issue.
You are not calling next() in your logger, so you're never getting to your router, which results in no response.
router.use(function (req, res, next) { // simple logger
if (req.method === 'GET')
console.log('executing query on id %s', JSON.stringify(req.params));
else if (req.method === 'PUT')
console.log('executing query on id %s', JSON.stringify(req.params));
else
console.log('executing query on id %s', JSON.stringify(req.params));
next();
});
Now the reason you are not seeing params in your logger is because params are only visible if the route definition has params. Your logger middleware doesn't define a specific route, therefore there are no params. A solution to this would be to use Router.param
router.param('bear_id', function(req, res, next, bear_id) {
if (req.method === 'GET')
console.log('executing query on id ' + bear_id);
else if (req.method === 'PUT')
console.log('executing query on id ' + bear_id);
else
console.log('executing query on id ' + bear_id);
next();
});
More simply:
router.param('bear_id', function(req, res, next, bear_id) {
console.log(req.method + ' with id ' + bear_id);
next();
});
This works this way by design, you can find more information on github:
https://github.com/strongloop/express/issues/2088
At the moment I have the following which sits below all my other routes:
app.get('*', function(req, res){
console.log('404ing');
res.render('404');
});
And according to the logs, it is being fired even when the route is being matched above. How can I get it to only fire when nothing is matched?
You just need to put it at the end of all route.
Take a look at the second example of Passing Route Control:
var express = require('express')
, app = express.createServer();
var users = [{ name: 'tj' }];
app.all('/user/:id/:op?', function(req, res, next){
req.user = users[req.params.id];
if (req.user) {
next();
} else {
next(new Error('cannot find user ' + req.params.id));
}
});
app.get('/user/:id', function(req, res){
res.send('viewing ' + req.user.name);
});
app.get('/user/:id/edit', function(req, res){
res.send('editing ' + req.user.name);
});
app.put('/user/:id', function(req, res){
res.send('updating ' + req.user.name);
});
app.get('*', function(req, res){
res.send('what???', 404);
});
app.listen(3000);
Alternatively you can do nothing because all route which does not match will produce a 404. Then you can use this code to display the right template:
app.error(function(err, req, res, next){
if (err instanceof NotFound) {
res.render('404.jade');
} else {
next(err);
}
});
It's documented in Error Handling.
I bet your browser is following up with a request for the favicon. That is why you are seeing the 404 in your logs after the 200 success for the requested page.
Setup a favicon route.
You can this at the end of all routes,
const express = require('express');
const app = express();
const port = 8080;
// All your routes and middleware here.....
app.use((req, res, next) => {
res.status(404).json({
message: 'Ohh you are lost, read the API documentation to find your way back home :)'
})
})
// Init the server here,
app.listen( port, () => {
console.log('Sever is up')
})
Hope it helpful, I used this code in bottom of routes
router.use((req, res, next) => {
next({
status: 404,
message: 'Not Found',
});
});
router.use((err, req, res, next) => {
if (err.status === 404) {
return res.status(400).render('404');
}
if (err.status === 500) {
return res.status(500).render('500');
}
next();
});
You can use this
const express = require('express');
const app=express();
app.set('view engine', 'pug');
app.get('/', (req,res,next)=>{
res.render('home');
});
app.use( (req,res,next)=>{
res.render('404');
})
app.listen(3000);
I wanted a catch all that would render my 404 page only on missing routes and found it here in the error handling docs https://expressjs.com/en/guide/error-handling.html
app.use(function (err, req, res, next) {
console.error(err.stack)
res.status(404).render('404.ejs')
})
This worked for me.
Very simple you can add this middleware.
app.use(function (req, res, next) {
//Capture All 404 errors
res.status(404).render("404.ejs")
})
404 error in a service is typically used to denote that the requested resource is not available. In this article we will see how to handle 404 error in express.
We need to handle the Error and Not-Found collectively as
Write two separate middleware for each,
// Import necessary modules
const express = require('express');
// Create a new Express app
const app = express();
// Define routes and middleware functions
app.get('/', (req, res) => {
res.send('Hello World!');
});
// Catch 404 Not Found errors and forward to error handler
app.use((req, res, next) => {
const error = new Error('Not Found');
error.status = 404;
next(error);
});
// Error handler middleware function
app.use((err, req, res, next) => {
// Set status code and error message based on error object
res.status(err.status || 500);
res.send({
error: {
message: err.message
}
});
});
// Start the server
app.listen(3000, () => {
console.log('Server started on port 3000');
});