I have a basic Express app which has a few routes.
One is as such:
router.post('/upload', (req, res) => {
let audioFile = req.files.audioFile;
const file = __dirname + '/../' + req.body.uploadLocation + audioFile.name;
mp3.mv(file, function(err) { // <--- HERE
if (err) {
return res.status(500).send(err);
}
res.send('File uploaded!');
});
});
Now, if you would try to upload a file to this route you would get a 500 and that's it. The highlighted line is a result of me changing variable name. Is there any way to get it so that it prints out the actual error? I am tripped up by this so often and it would make it an awful lot quicker if the terminal output just told me the normal JS error like it does on the browser or when I'm running node normally.
In Express there is middleware to handle errors. In the a base setup of express you'll find:
// error handler
app.use(function(err, req, res, next) {
...
// render the error page
res.status(err.status || 500);
res.json({ error: err });
});
Just add a console.error there:
// error handler
app.use(function(err, req, res, next) {
console.error(err.stack); // <- HERE
...
// render the error page
res.status(err.status || 500);
res.json({ error: err });
});
I want to create a function that return a http.Server and
Serve the text of the file testText.txt in the body of the HTTP response
when a GET request is made to the '/' route.
Parse the request for a "paragraphs" parameter.
That parameter must be an integer and represent the number of
paragraph you want to receive starting from the beginning of the test text.
Return the appropriate content in the body of the response.
If any error happens, return a 500 error.
If the provided route is not known, return a 404 error.
here is what i have so far
function makeServer() {
return http.createServer(function(req, res){
if(req.url === '/'){
fs.readFile('testText.txt', function(err , para){
console.log("Data", para);
res.end();
});
console.log("The end");
}
}
I would expect to do something like this,
var express = require('express');
var app = express();
//Handle 404 here
app.use(function (req, res, next) {
res.status(404).send({
message: "Page Not Found"
})
});
Inject the GET request to your default route
app.get('/', (req, res) => {
// **modify your existing code here**
fs.readFile('testText.txt', (e, para) => {
if (e) {
res.status(500).send({
message: "Something went wrong"
})
}
res.send(para);
});
});
app.listen(5555);
As you have mentioned in your question use that err object inside the function such as below:
function makeServer() {
return http.createServer(function(req, res){
if(req.url === '/'){
fs.readFile('testText.txt', function(err , para){
if (err) {
res.status(500).send({
message: "Something went wrong"
})
// error handling
} else {
console.log("Data", para);
res.end();
}
});
console.log("The end");
}
}
Firstly, Welcome to the node world...
1) Work with file in res
Please refer this answer. It will help you.
2) Error code 500 if any error
res.status(500).json({success: 0, error 'Something went wrong'});
3) For handle 404 if route not matched
var createError = require('http-errors');
//Install via this command-> npm i http-errors --save
app.use(function (req, res, next) {
next(createError(404));
});
I am trying to write a middleware to handle errors. But I cannot figure out how to send the correct format to my frontend. Below I am going to list all of my attempts in hopes of helping you help me.
Attempt 1
app.use(function(err, req, res, next) {
const formatted = err;
res.send(formatted)
});
result in postman
{ "code": 422 }
Attempt 2
app.use(function(err, req, res, next) {
const formatted = `${err}`;
res.send(formatted)
});
result (postman)
Error: Request returned error code: 422 and body: {"status":422,"title":"The display name: build_id has already been used on this product.","type":"https://developer.bigcommerce.com/api#api-status-codes","errors":{"display_name":"The display name: build_id has already been used on this product."}}
That is the data i want but i need it in json
Question Why is there more data revealed after string interpolation? How can i format it to json?
You're probably looking for res.json(err) if I had to guess?
https://expressjs.com/en/api.html#res.json
EDIT: Full example:
app.use(function(err, req, res, next) {
if (err) res.json(err)
});
You can do it in this way
app.use(function(err, req, res, next) {
if (err) {
res.json({
status: "error",
error: `${err}` // <-- edited
});
} else {
next();
}
});
I'm new with nodeJs and i'm actually following a tutorial about it.
In the tutorial, a code was used:
In a verify.js file the following function was written:
exports.verifyOrdinaryUser = function (req, res, next) {
// check header or url parameters or post parameters for token
var token = req.body.token || req.query.token || req.headers['x-access-token'];
// decode token
if (token) {
// verifies secret and checks exp
jwt.verify(token, config.secretKey, function (err, decoded) {
if (err) {
var err = new Error('You are not authenticated!');
err.status = 401;
return next(err);
} else {
// if everything is good, save to request for use in other routes
req.decoded = decoded;
next();
}
});
} else {
// if there is no token
// return an error
var err = new Error('No token provided!');
err.status = 403;
return next(err);
}
};
and in another file, the function was called so :
/*****........****/
.post(verify.verifyOrdinaryUser, function(req, res, next){
/******.......*****/
everything is working fine without problem.
1- I don't understand why the function verify.verifyOrdinaryUser is not called so :
verify.verifyOrdinaryUser(req, res, next)
with his parameter (how is it possible that we call a function without his parameter .?
next , i've written a function :
exports.verifyAdmin = function(req, res, next){
if(req.decoded._doc.admin == false){
var err = new Error('You cannot access to this ressource!');
err.status = 401;
return next(err);
}
else {
next();
}
};
in the same file, to verify if a user is a admin or not, i have to call this function after the verifyOrdinaryUser function,
my problem is i don't know how i can make call of this function, with or without the parameters.
Thank you.
1- I don't understand why the function verify.verifyOrdinaryUser is
not called so : verify.verifyOrdinaryUser(req, res, next)
In simplest terms, That's because Express takes care of sending those parameters to the specified middleware instead of you specifying it here
And in function verify.verifyOrdinaryUser, The function is requesting for 3 parameters req, res, next and it receives those three parameters, if it requests for a parameter that doesn't exist, That parameters value will be undefined.
my problem is i don't know how i can make call of this function, with
or without the parameters.
Just call it like
/*****........****/
.post(verify.verifyOrdinaryUser, verify.verifyAdmin, function(req, res, next){
/******.......*****/
And in the functions code you can request for the parameters you need
exports.verifyAdmin = function(req, res){
if(req.decoded._doc.admin == false){
...
Hope this gives you some sense on whats going on, You should google for Node JS Middlewares and simple tutorials based on Node JS and Express.
I'm using Node.js as a backend API server for an iPhone client. I'm using Passport.js to authenticate with a local strategy. The relevant code is below:
// This is in user.js, my user model
UserSchema.static('authenticate', function(username, password, callback) {
this.findOne({ username: username }, function(err, user) {
if (err){
console.log('findOne error occurred');
return callback(err);
}
if (!user){
return callback(null, false);
}
user.verifyPassword(password, function(err, passwordCorrect){
if (err){
console.log('verifyPassword error occurred');
return callback(err);
}
if (!passwordCorrect){
console.log('Wrong password');
return callback(err, false);
}
console.log('User Found, returning user');
return callback(null, user);
});
});
});
and
// This is in app.js
app.get('/loginfail', function(req, res){
res.json(403, {message: 'Invalid username/password'});
});
app.post('/login',
passport.authenticate('local', { failureRedirect: '/loginfail', failureFlash: false }),
function(req, res) {
res.redirect('/');
});
Right now, I have managed to redirect a failed login to /loginfail, where I send back some JSON to the iPhone client. However, this doesn't have enough granularity. I want to be able to send back the appropriate errors to the iPhone client, such as: "No user found" or "Password is wrong". With my existing code, I don't see how this can be accomplished.
I tried to follow the examples for a custom callback on the passport.js site, but I just can't get it to work due to lack of node understanding. How could I modify my code so that I'd be able to send back a res.json with an appropriate error code/message?
I am trying something like this now:
// In app.js
app.post('/login', function(req, res, next) {
passport.authenticate('local', function(err, user, info) {
if (err) { return next(err) }
if (!user) {
console.log(info);
// *** Display message without using flash option
// re-render the login form with a message
return res.redirect('/login');
}
console.log('got user');
return res.json(200, {user_id: user._id});
})(req, res, next);
});
// In user.js
UserSchema.static('authenticate', function(username, password, callback) {
this.findOne({ username: username }, function(err, user) {
if (err){
console.log('findOne error occurred');
return callback(err);
}
if (!user){
return callback(null, false);
}
user.verifyPassword(password, function(err, passwordCorrect){
if (err){
return callback(err);
}
if (!passwordCorrect){
return callback(err, false, {message: 'bad password'});
}
console.log('User Found, returning user');
return callback(null, user);
});
});
});
But back when I try to console.log(info), it just says undefined. I don't know how to get this custom callback working...Any help would be appreciated!
I had a similar issue with Passport and failed login responses. I was building an API, and wanted all responses to be returned as JSON. Passport responds to an invalid password with status: 401 and body: Unauthorized. That's just a text string in the body, not JSON, so it broke my client which expected all JSON.
As it turns out, there is a way to make Passport just return the error to the framework instead of trying to send a response itself.
The answer is to set failWithError in the options passed to authenticate:
https://github.com/jaredhanson/passport/issues/126#issuecomment-32333163
From jaredhanson's comment in the issue:
app.post('/login',
passport.authenticate('local', { failWithError: true }),
function(req, res, next) {
// handle success
if (req.xhr) { return res.json({ id: req.user.id }); }
return res.redirect('/');
},
function(err, req, res, next) {
// handle error
if (req.xhr) { return res.json(err); }
return res.redirect('/login');
}
);
This will invoke the error handler after Passport calls next(err). For my app, I wrote a generic error handler specific to my use case of just providing a JSON error:
// Middleware error handler for json response
function handleError(err,req,res,next){
var output = {
error: {
name: err.name,
message: err.message,
text: err.toString()
}
};
var statusCode = err.status || 500;
res.status(statusCode).json(output);
}
Then I used it for all api routes:
var api = express.Router();
...
//set up some routes here, attached to api
...
// error handling middleware last
api.use( [
handleError
] );
I didn't find the failWithError option in the documentation. I stumbled upon it while tracing through the code in the debugger.
Also, before I figured this out, I tried the "custom callback" mentioned in the #Kevin_Dente answer, but it didn't work for me. I'm not sure if that was for an older version of Passport or if I was just doing it wrong.
I believe the callback function that your 'authenticate' static calls (called 'callback' in your code) accepts a 3rd parameter - "info" - which your code can provide. Then, instead of passing in the { failureRedirect: ...} object, pass in a function which takes 3 arguments - err, user, and info. The "info" you provided in your authenticate method will be passed to this callback.
Passport calls this scenario "custom callback". See the docs here:
http://passportjs.org/guide/authenticate/
There is an official documentation for Custom Callback:
app.get('/login', function(req, res, next) {
passport.authenticate('local', function(err, user, info) {
if (err) { return next(err); }
if (!user) { return res.redirect('/login'); }
req.logIn(user, function(err) {
if (err) { return next(err); }
return res.redirect('/users/' + user.username);
});
})(req, res, next);
});
https://github.com/passport/www.passportjs.org/blob/master/views/docs/authenticate.md
As per the official documentation of Passport you may use custom callback function to handle the case of failed authorization and override the default message.
If you are developing REST API and then you would want to send out pretty JSON response something as below:
{
"error": {
"name": "JsonWebTokenError",
"message": "invalid signature"
},
"message": "You are not authorized to access this protected resource",
"statusCode": 401,
"data": [],
"success": false
}
I was using Passport JWT authentication to secure some of my routes and was applied the authMiddleware as below:
app/middlewares/authMiddleware.js
const express = require('express');
const router = express.Router();
const passport = require('passport');
const _ = require('lodash');
router.all('*', function (req, res, next) {
passport.authenticate('local', function(err, user, info) {
// If authentication failed, `user` will be set to false. If an exception occurred, `err` will be set.
if (err || !user || _.isEmpty(user)) {
// PASS THE ERROR OBJECT TO THE NEXT ROUTE i.e THE APP'S COMMON ERROR HANDLING MIDDLEWARE
return next(info);
} else {
return next();
}
})(req, res, next);
});
module.exports = router;
app/routes/approutes.js
const authMiddleware = require('../middlewares/authMiddleware');
module.exports = function (app) {
// secure the route by applying authentication middleware
app.use('/users', authMiddleware);
.....
...
..
// ERROR-HANDLING MIDDLEWARE FOR SENDING ERROR RESPONSES TO MAINTAIN A CONSISTENT FORMAT
app.use((err, req, res, next) => {
let responseStatusCode = 500;
let responseObj = {
success: false,
data: [],
error: err,
message: 'There was some internal server error',
};
// IF THERE WAS SOME ERROR THROWN BY PREVIOUS REQUEST
if (!_.isNil(err)) {
// IF THE ERROR IS REALTED TO JWT AUTHENTICATE, SET STATUS CODE TO 401 AND SET A CUSTOM MESSAGE FOR UNAUTHORIZED
if (err.name === 'JsonWebTokenError') {
responseStatusCode = 401;
responseObj.message = 'You are not authorized to access this protected resource';
}
}
if (!res.headersSent) {
res.status(responseStatusCode).json(responseObj);
}
});
};
You can do that without custom callbacks using property passReqToCallback in your strategy definition:
passport.use(new LocalStrategy({passReqToCallback: true}, validateUserPassword));
Then you can add your custom auth error code to the request in your strategy code:
var validateUserPassword = function (req, username, password, done) {
userService.findUser(username)
.then(user => {
if (!user) {
req.authError = "UserNotFound";
return done(null, false);
}
And finally you can handle these custom errors in your route:
app.post('/login', passport.authenticate('local', { failWithError: true })
function (req, res) {
....
}, function(err, req, res, next) {
if(req.autherror) {
res.status(401).send(req.autherror)
} else {
....
}
}
);
A short workaround is to emulate the Flash method call which intended originally to support connect-flash and to use this method to return the JSON object.
first define the "emulator":
var emulateFlash = function (req, res, next) {
req.flash = (type, message) => {
return res.status(403).send({ status: "fail", message });
}
next();
}
this will inject the flash method which will send the error JSON object upon failure.
In the route do the following:
1st, use the emulator across the board using:
router.use(emulateFlash);
One can instead use the emulateFlash method on each route needed.
2nd, on the route when using authenticate, specify the failureFlash option using a message:
router.route("/signin")
.post(.authenticate('local', { session: false, failureFlash: "Invalid email or password."}), UsersController.signIn);
I tested this for both failed authentication as well as successful and found it working. Looking at the code I could not find any other way to return an object other than implementing the callback method which requires much more work.