Send data back to node.js server from front-end

Question

I am new to Node.js and I'm trying to figure out for few days how to make a simple login-register feature for a website using Express.js with EJS template engine and MySql.

I have installed Node on my PC and I've used the Express-Generator to make a basic folder structure (views, routes, public folders).

I understand how I can pass variables from node to the front end using ejs but I don't know how to pass it back. I've tried watching some tutorials on the internet but nothing seems to make me see the logic. Where do I put the MySql code? How can I pass back the input values once the user clicks "SUBMIT"?

Answer 1

How says Jake, I suggest to use Sequelize for MySQL.

I will try to make a small steps for your start, and after you can study more about each process and tool.

1) Front-end (EJS);

  <form id="login" action="/login" method="post">
      <input name="username" type="text">
      <input name="password" type="password">
      <input type="submit">Ok</input>
  </form>

Here, the form will request the route login . The route:

2) Route

module.exports = function (app){

    var login = app.controllers.login;

    app.get('/', login.index);
    app.post('/login', login.login)
};

The route will call the login method in the controller called login.js .

3) Controller

module.exports = function(app) {

  var sequelize = require('./../libs/pg_db_connect'); // resquest lib of connection to mysql/postgres

  var LoginController = {
    index: function(req, res) {
      res.render('login/index');
    },

    login: function(req, res) {    
      var query = "SELECT * FROM users"; // query for valid login

      sequelize.query(query, { type: sequelize.QueryTypes.SELECT}).then(function(user){    

        if (req.body.username == user[0].username  && req.body.password === user[0].password ){ 
            res.redirect("/home");     
          } else {
            res.render("login/invalid_access");
          }

      });

    }
  };
  return LoginController;
};

In this point, is exec the query for to valid the login and verify if user can be log in. Request method is the main point.

For response and send information to view, it used res.SOME_METHOD :

res.send();

res.end();

res.download();

res.json();

Plus: Sequelize MySQL connection.

In the express structure, it's localized in lib/my_db_connection.js:

var Sequelize = require('sequelize');
module.exports = new Sequelize('database_name', 'user', 'pass', {
    host: 'localhost',
    dialect: 'mysql',
    pool: {
        max: 10,
        min: 0,
        idle: 10000
    },
});

I suggest before you code, read the necessary docs.

Answer 2

You're going to have to use some sort of AJAX library (or vanilla js ajax) to send the information to a http endpoint you set up in express. For simple stuff the jquery ajax methods will do just fine. You will likely are looking to make a POST request.

As for the MySql code, checkout Sequelize. Its a cool library for interacting with sql databases from express. Its similar to how mongoose works for mongo.