Express Validator using 5.3.0 middleware function - express

Question

const app = require('express')();
const session = require('express-session');
const {
check,
validationResult
} = require('express-validator/check');
app.use(session({
secret: 'keyboard cat',
resave: false,
saveUninitialized: true,
cookie: { secure: false }
}))
app.get("/test", [
// username must be an email
check('username').not().isEmpty(),`//.withCustomMessage() based on the content of req.session`
// password must be at least 5 chars long
check('password').not().isEmpty()
],(req,res)=>{
console.log("req.session", req.session);
// Finds the validation errors in this request and wraps them in an object with handy functions
const errors = validationResult(req);
if (!errors.isEmpty()) {
return res.status(422).json({ errors: errors.array() });
}
//console.log("req.session",req.session);
});
app.get("/",(req,res,next)=>{
req.session.message = "beoulo ";
// console.log(req.session);
res.status(200).json({
"status" :"session set"
});
});
app.listen(3000,()=>{
console.log("Listening on port 3000!!!");
});
Is passing Check directly as middleware the only way to use it .?
Can we still use req.checkbody(field,errormessage) format or something equivalent inside a seperate middleware function cause the error message has to be taken from the session
I want to access a variable from req.session and based on that generate a custom error message
previous implementation worked fine as it used req.checkBody()
with new changes what should I do to handle this scenario .

Answer 1

You can rewrite the default error messages inside of your own handler.
Assuming that your error messages are stored in req.session.errors, and that this is an object that maps a particular validation to a particular error message.
For instance:
// req.session.errors =
{
"USERNAME_EMPTY" : "The username cannot be empty",
"PASSWORD_EMPTY" : "The password cannot be empty",
}
Next, you would provide custom messages for each validation, that match the keys of the abovementioned object:
check('username').not().isEmpty().withMessage('USERNAME_EMPTY')
check('password').not().isEmpty().withMessage('PASSWORD_EMPTY')
Finally, inside your handler, you perform a lookup from the validation errors to the error message values:
if (! errors.isEmpty()) {
const list = errors.array();
list.forEach(error => {
error.msg = req.session.errors[error.msg] || error.msg;
});
return res.status(422).json({ errors: list });
}
Or just depend on an older version of express-validator so you can keep using the legacy API.