how to stop form submission with express.js and node

Question

how to stop form submission with express.js and node

I am validating my form with express-validator...if I have errors, what's the best way to stop the form from submitting and go back to the login page. This is what I have, which works, just looking for best way to handle this (not sure about the return statement).

//routes/index.js
exports.login.post = function(req, res){
  req.assert('username', 'Please enter username').notEmpty();
  req.assert('password', 'Please enter password').notEmpty();
  res.locals.errors = req.validationErrors(true);

  if ( res.locals.errors ) {
    console.log(res.locals.errors);
    var d = { title: 'Login' };
    res.render('login', { d: d });
    return;
  }

 //do login here if no errors
};

I also do not know how to get at original values in form template (ejs).

I tried passing req.param in, but it is empty.

The err object only has those fields with errors, so if I enter username, but leave password blank, I only get password in err object, not username...so I need req.param.username, but when I pass { q: req.param} and use <%= inspect(q) %> it is empty.

update: req.body gives me the original post parameters to pre-populate the form. so you need err stack and req.body stack to have a good experience.

forms
validation
node.js
express
ejs

Answer 1

What I suggest doing is using something like flashify to set a flash notification and redirect the request back to the view.

So you can do something like:

if ( res.locals.errors ) 
{
  res.flash('error','bad username/password');
  req.session.formData = req.body;
  res.redirect('back');
}

Then inside the view, you just check if flash.error exists, and output the message if it does, then: <%= flash.error %> :)

Answer 2

This is what I do

app.post('/form_process',validateForm,form.handle)
function validateForm(req,res,next){
req.assert('username', 'Invalid Username').notEmpty().isAlpha();
req.assert('password', 'Invalid Password').notEmpty().isAlpha();

var errors = req.validationErrors();
if (errors) {
//res.send(errors,500);
var    original_values = {
username : req.param('username'),
password : req.param('password')
}
res.render('login',{errorMsg:errors,original:original_values,title:"Login error"})
return;
}
else next()
}