Express JS redirect to form with invalid email

Question

I am new to nodeJS and I have been trying to create a registration form with validation.

The validation part is complete with sql query statements, but I am having trouble redirecting from my server side back to registration form with a message info such as 'Email address already exists'.

How do I process this on the client 'register.js' ?

register.js

      <form id='register-form' method="POST"  action="http://localhost:3306/register">

server.js

app.post('/register', (req,res) => {  
var email = req.body.email;
var password = req.body.password;

let sql = "SELECT * FROM user WHERE email='" + email + "'";

db.query(sql,(err,result) => {
if (err) throw err;

if (result.length > 0) {
  console.log("user already exists");
  res.redirect('http://localhost:3000/#/Register');
} else {
  insertUser(email,password);
  res.send(email + " has been added to database");
}

score 0 · Answer 1 · answered Jan 14 '18 at 19:45

There are mutliple queries...

I am not sure if your register.html file is within any folder(say, public) that is publicly accessed by using express static middleware. If yes, I hope you are setting the static middleware

app.use(express.static('public'));

Do you want to send a response as Bad Request if email id is already present in DB?, then please try below
if(!result.length)
res.status(400).json('Email Id Already exists');

OR

res.status(400).send(400, {error:'Email Id Already exists'});

You need a body-parser to parse the URL encoded notation..sample code which worked for me:

let express=require('express');
let app = express();
let server = require('http').createServer(app);

var bodyParser = require('body-parser');
var parseUrlencoded = bodyParser.urlencoded({ extended: false });

app.use(express.static('public'));


app.post('/register', parseUrlencoded, (req,res) => {
    var email = req.body.email;
    var password = req.body.password;
      if (!email) {
        res.writeHead(404,
             {Location: 'http://localhost:3306/register.html'}
         );
        res.end();
       }
       else{
          res.status(200).json('email is not empty');
        }
});
server.listen(3306, ()=> console.log('app started'));

Some examples: Proper way to set response status and JSON content in a REST API made with nodejs and express

Error: Can't set headers after they are sent to the client

yup, so 1 query checks if the email exists or not in the db and the other query insertUser(email,password) is for the SQL statement 'INSERT ....' I basically want to redirect back to my register form with a message displaying 'Email already exists' like in any generic form registration. My register form is not in a pubilic folder, rather I created a route for it using react routers — Cliff Yuen, Jan 15 '18 at 15:07

Express JS redirect to form with invalid email

1 Answers1