I'm writing some rendering-code for an Express app, I wish to catch errors and then output them in the function render, but I'm not sure how I'm going to move them from one method to the other.
app.get('/user/makeRider', auth,
(req, res, next) => {
req.user.user.makeRider(req.query)
.catch(error)
.then(render(req, res));
}
);
var render = (req, res) => {
var response = {
params: req.query,
user: req.user.fulluser
};
res.json(response);
},
error = (reason) => {
reason.errors.forEach((error) =>{
console.log(error);
});
return;
};
You can use error function as your last midleware in the chain and simply pass the request to the next chain:
var render = (req, res) => {
var response = {
params: req.query,
user: req.user.fulluser
};
res.json(response);
}
app.get('/user/makeRider', auth,
(req, res, next) => {
req.user.user.makeRider(req.query)
.catch(next)
.then(render(req, res));
}
);
app.use((reason, req, res, next) => {
res.send(reason.errors);
// or you can send them as json: res.status(404).json({errors: reason.errors})
});
Beware of hoisting issue in your code, the variable declarations are hoisted to the top, but not their assignments, error and render function may appear as undefined when accessed from your route.
A quick, but maybe not the most elegant solution would be to add errors as a parameter to your render function, then you could do something like this:
app.get('/user/makeRider', auth,
(req, res, next) => {
req.user.user.makeRider(req.query)
.catch((reason)=>{
render(req, res, reason.errors)
})
.then(render(req, res));
}
);
var render = (req, res, errs) => {
var response = {
params: req.query,
user: req.user.fulluser
};
res.json(response);
};
Related
I would like to get the data from session variable (req.user.username) then use it for posting. I'm using passportjs as authentication. I'm using router. Here is my code:
router.use('/login', passport.authenticate("local-register", async (err, user, info) => {
if (err) {
return next('Error');
}
if (!user) {
return next('Error');
}
req.user = user;
return req.login(user, (error: Error) => {
if (error) {
return next('Error');
}
return req.session.save((erro: Error) => {
if (erro) {
return next('Error');
}
return next();
});
});
})(req, res, next);)
router.get('/', async (req, res) => {
console.log(req.user.username) // working just fine
});
router.post('/upload', async (req, res) => {
const uploaderName = req.user.username // I'm getting undefined
const upload = await database.query('INSERT INTO user WHERE username=$1', [uploaderName])
console.log(uploaderName);
})
So I finally found the answer to the question. For those who will encounter the problem in the future. You just add the session middleware AGAIN on the top of the routes. If your routes are separated to the main server file.
/src/routes/routes.ts -> add again the middleware on top.
const app = router();
app.use(sessions) // -> right here you need to add the middleware again to //access the req.user session variable
app.get('/', async (req, res) => {
console.log(req.user.username) // working just fine
});
app.post('/upload', async (req, res) => {
const uploaderName = req.user.username // I'm getting undefined
const upload = await database.query('INSERT INTO user WHERE username=$1', [uploaderName])
console.log(uploaderName);
})
I have an async function as a route handler, and i'd like to have errors handled as some kind of middleware. Here is my working attempt:
router.get(
"/",
asyncMiddleware(
routeProviderMiddleware(
async ({ y }) => ({
body: await db.query({x: y})
})
)
)
)
// This is the middleware that catches any errors from the business logic and calls next to render the error page
const asyncMiddleware = fn =>
(req, res, next) => {
Promise.resolve(fn(req, res, next))
.catch(next)
}
// This is a middleware that provides the route handler with the query and maybe some other services that I don't want the route handler to explicitly access to
const routeProviderMiddleware = routeHandlerFn => async (req, res) => {
const {status = 200, body = {}} = await routeHandlerFn(req.query)
res.status(status).json(body)
}
What I strive to is a way to make the route declaration cleaner - I don't want the 2 middleware wrappers there, ideally i'd like for the business logic function there only, and somehow declare that every route is wrapped in these.
Even combining the two middlewares together would be nice, but I didn't manage.
I use following approach:
Create asyncWrap as helper middleware:
const asyncWrap = fn =>
function asyncUtilWrap (req, res, next, ...args) {
const fnReturn = fn(req, res, next, ...args)
return Promise.resolve(fnReturn).catch(next)
}
module.exports = asyncWrap
All your routes/middlewares/controllers should use this asyncWrap to handle errors:
router.get('/', asyncWrap(async (req, res, next) => {
let result = await db.query({x: y})
res.send(result)
}));
At app.js, the last middleware will receive the errors of all asyncWrap:
// 500 Internal Errors
app.use((err, req, res, next) => {
res.status(err.status || 500)
res.send({
message: err.message,
errors: err.errors,
})
})
Express 5 automatically handles async errors correctly
https://expressjs.com/en/guide/error-handling.html currently says it clearly:
Starting with Express 5, route handlers and middleware that return a Promise will call next(value) automatically when they reject or throw an error. For example:
app.get('/user/:id', async function (req, res, next) {
var user = await getUserById(req.params.id)
res.send(user)
})
If getUserById throws an error or rejects, next will be called with either the thrown error or the rejected value. If no rejected value is provided, next will be called with a default Error object provided by the Express router.
I have shown that in an experiment at: Passing in Async functions to Node.js Express.js router
This means that you will be able to just make the callback async and use await from it directly without any extra wrappers:
router.get("/", async (req, res) =>
const obj = await db.query({x: req.params.id})
// Use obj normally.
)
and errors will be correctly handled automatically.
Express permits a list of middlewares for a route and this approach sometimes works for me better than higher-order functions (they sometimes look like an overengineering).
Example:
app.get('/',
validate,
process,
serveJson)
function validate(req, res, next) {
const query = req.query;
if (isEmpty(query)) {
return res.status(400).end();
}
res.locals.y = query;
next();
}
function process(req, res, next) {
Promise.resolve()
.then(async () => {
res.locals.data = await db.query({x: res.locals.y});
next();
})
.catch((err) =>
res.status(503).end()
);
}
function serveJson(req, res, next) {
res.status(200).json(res.locals.data);
}
What you can do is add an error handlers after your routes. https://expressjs.com/en/guide/error-handling.html
app.use(function (err, req, res, next) {
console.error(err.stack)
res.status(500).send('Something broke!')
})
What I ended up doing is unifying the wrappers like this:
const routeProvider = routeHandlerFn => async (req, res, next) => {
try {
const {status = 200, body = {}} = await routeHandlerFn(req.query)
res.status(status).json(body)
} catch(error) {
next(error)
}
}
This wrapper is all any route would need. It catches unexpected errors and provides the route handler with the needed params.
I'm developing a module which I'm using for passport authentication with ExpressJS, and I came up with this solution to gather all the passports methods I'm using:
// passport-controller-js
exports.signup = (passport) => (req, res, next) => {
// Authenticate methods ================
passport.authenticate('local-signup', function(err, user, info) {
if (err) {
return next(err); // will generate a 500 error
}
// Saving user...
return res.send({ success : true, message : 'signup succeeded' });
})(req, res, next);
};
exports.signin = (passport) => (req, res, next) => {
passport.authenticate('local-login', function(err, user, token, info) {
if (err) {
return next(err); // will generate a 500 error
}
req.login(user, loginErr => {
if (loginErr) {
return next(loginErr);
}
return res.send({ success : true, message : 'signin succeeded' });
});
})(req, res, next);
};
But since this module will increase adding more strategies I'm thinking if there is a way to put all of them inside a module.exports like:
module.exports = (passport) => {
function signin(req, res, next) {
passport.authenticate('local-login', function(err, user, token, info) {
if (err) {
return next(err); // will generate a 500 error
}
req.login(user, loginErr => {
if (loginErr) {
return next(loginErr);
}
return res.send({ success : true, message : 'signin succeeded' });
});
})(req, res, next);
};
I know that dosn't work Im just wondering if there is a possible solution like that so when I need to require those methods on my router file for example I can do this:
// auth.js (passport is passed from index.js)
const passportController = require('../controllers/passport-controller')(passport);
// Process the signup form
router.post('/signup', passportController.signup);
router.post('/signin', passportController.signin);
Instead of:
// auth.js (passport is passed from index.js)
const passportController = require('../controllers/passport-controller');
// Process the signup form
router.post('/signup', passportController.signup(passport));
router.post('/signin', passportController.signin(passport));
As you can see is just matter of looking for the most legible way to code and keep it simpler as possible.
Any help would be appreaciated, thank you very much.
Sounds like you want to make a module that exports a single function which returns an object. The syntax for that is
module.exports = passport => ({
signup(req, res, next) {
…
},
signin(req, res, next) {
…
}
});
I have some code duplication that I'd like to factorize.
app.post('/login', (req, res) =>{
reqOptions = {...};
request(reqOptions, (error, response, body) => {
if (!error) {
res.statusCode = response.statusCode;
res.json(body)
}
else {
res.statusCode = 503;
res.json(body)
}
});
});
The logic in the request callback is always the same, and I try to find a way to get it out into a reusable function, like this :
function requestCallback(error, reponse, body) {
....
}
app.post('/login', (req, res) =>{
reqOptions = {...};
request(reqOptions, requestCallback);
});
My problem is : how can I get access to req and res in the requestCallback() function ? Do I need to pass everything as arguments ?
Many thx
You can use Function.prototype.bind()
function requestCallback(_req, _res, error, reponse, body) {
....
}
request(reqOptions, requestCallback.bind(null, req, res));
Yes, you can just simply pass req and res as arguments to requestCallback()
I have an ExpressJS controller that list all my users
userCtrl.get :
get(req, res, next) {
var func = function(err, data) {
if (err) return next(err);
return res.json(data);
};
if (req.params[this.idName])
this._getById(req.params[this.idName], func);
else
this._getAll(func);
}
_getById(id, fn) {
this.ObjectClass.findById(id, fn);
}
_getAll(fn) {
this.ObjectClass.findAll(fn);
}
I'd like to call it from another road, in such a way that res.json() will filter a field of this json
Something like :
router.get ('/services/:serviceKey/authBridge/users', function(req, res, next) {
function anonJs(x) {
x.forEach(s => s.credential = null);
res.json(x);
}
res.json = anonJs;
userCtrl.get(req, res, next);
});
The problem is, with this last piece of code I end up with a recursion as I call res.json that is now defined as anonJS
You must store the reference to the old function before replacing it.
router.get ('/services/:serviceKey/authBridge/users', function(req, res, next) {
var json = res.json;
res.json = function(x) {
x.forEach(s => s.credential = null);
json(x);
}
userCtrl.get(req, res, next);
});