How to handle error in express with class? - node.js

Question

I am trying to handle error with class constructor in a better way. I named my class HttpError that is written below, the problem is HttpError doesn't work properly.
This is "app.js" file:
const express = require('express');
const app = express();
const placesRoutes = require('./routes/placesRoutes');
app.use('/api/places',placesRoutes);
app.get('/', (req, res, next) => {
res.json({message: 'the server is working.'});
next();
});
app.use((error, req, res, next)=> {
if(res.headerSent){
return next(error);
}
res.status(error.code || 500);// This error shows when I am entering wrong pid
res.json({message: 'Does not match any route'});
})
app.listen(5000);
and this is placesRoutes.js:
const express = require('express');
const HttpError = require('../models/httpError');
const router = express.Router();
const DUMMY_PLACE = [
{
id: '1',
name: 'jahid',
address: 'Rajoir, Rayenda, Sarankhola, Bagerhat',
email: 'gahid#gmail.com',
password: 'jahid5868'
},
{
id: '2',
name: 'saiful',
address: 'Rajoir, Rayenda, Sarankhola, Bagerhat',
email: 'gahid#gmail.com',
password: 'jahid5868'
},
{
id: '3',
name: 'sadiqul',
address: 'Rajoir, Rayenda, Sarankhola, Bagerhat',
email: 'gkaid#gmail.com',
password: 'jahid5868'
},
{
id: '4',
name: 'hasib',
address: 'Rajoir, Rayenda, Sarankhola, Bagerhat',
email: 'ahid#gmail.com',
password: 'jahid5868'
},
]
router.get('/:pid', (req, res, next) => {
const sid = req.params.pid;
const data = DUMMY_PLACE.find(p=> p.id === sid);
if(!data){
return next(new HttpError('Does not found uid', 404));
}
res.json({data});
});
module.exports = router;
and this is "HttpError.js":
class HttpError extends Error {
constructor(message, statusCode) {
super();
this.message = message;
this.statusCode = statusCode;
}
};
module.exports = HttpError;
When I am entering /api/places/:(wrong-pid). It doesn't show HttpError rather it's showing the error 500 from bottom of app.js.
I am new to express so please don't bother if my question doesn't make sense.

Answer 1

With the above code an instance of HttpError gets passed to the error handling middleware, but you do not really use it there. You probably wanted to do something like:
app.use((error, req, res, next)=> {
if(res.headerSent){
return next(error);
}
if(error instanceof HttpError) {
res.status(error.statusCode);
res.json({message: error.message});
} else {
res.status(error.code || 500);
res.json({message: 'Does not match any route'});
}
})

Answer 2

So basically you have many ways of handling Errors, I like to use try/catch blocks very simple to understand and very useful and clear. You're doing a block asking him to do something if it's getting an error it's passing it to the catch block.
For example:
const validateUser = async (req, res, next) => {
try {
const { email, password } = req.body
if (!email || !password) {
throw new ErrorHandler(404, 'Missing required email and password fields')
}
const user = await db.User.findOne({ where: { email }});
if (!user) {
throw new ErrorHandler(404, 'User with the specified email does not exists')
}
next()
} catch (error) {
next(error)
}
}
so we try something (getting data checking it) if there is an error its passing to the catch block.
another simplest example:
try {
capture = await payPalClient.client().execute(request);
captureID = capture.result;
// console.log(captureID)
} catch (err) {
// 4. Handle any errors from the call
return res.status(500).send({
status: 500,
error: err,
});
}
trying something (some paypal stuff from one of my code not important).
if I'm getting an error from it I return a response (500 with a message of error .)
you can check on google for error handling express try/catch