Getting ready

First of all we need to create a users table in our database to store username and password (hashed version of user’s password). This hashing is done automatically by Auth component using it’s method hashPasswords() when it finds password in $data.

Run below sql to create users table.

CREATE TABLE `users` (
`id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`username` VARCHAR(255) NOT NULL,
`password` CHAR(40) NOT NULL,
PRIMARY KEY(`id`)
);

List of all files we will be creating in this post.

• AppController.php in /app/ folder
• UsersController.php in /app/controllers/ folder
• login.ctp in /app/views/users/ folder
• signup.ctp in /app/views/users/ folder

> <h3>AppController.php File< h3> This file mainly contains global data which is used by all controllers of the application, in our case we have only users controller. This file will be containing below code.

<?php
class AppController extends Controller {
       var $components = array('Session','Auth');
       var $helpers=array('Session');

}
?>

Explanation :

It has two variables one is $components and other one is $helpers. $components variable holds all the components utilized by all controllers, so we specified Auth component. Session component and Session helper is basically used to set session messages and show those messages in view respectively.

UsersController.php File

This is the heart of our logic. It contains functionality of login, signup and logout. Content of this file is…

<?php
class UsersController extends AppController {

    function beforeFilter() {
            parent::beforeFilter();
            $this->Auth->allow('signup');
      }
    function login() {}

    function logout()
    {
        $this->Session->setFlash('You are logged out!');
        $this->redirect($this->Auth->logout());
    }

    function signup()
    {

        if (!empty($this->data)) {
              $this->User->create();
              if ($this->User->save($this->data)) {
              $this->Session->setFlash('User saved!');
              $this->redirect(array('action'=>'login'));
            }
       else {
               $this->Session->setFlash('User not saved! There were some errors. Please rectify them and retry.');
             }

            }

          }

}
?>

Explanation :

First of all, as it is inheriting from AppController, it will have Auth component loaded by default which will process all requests of client. Auth component only allows to access only login function, so to access signup() for adding new users we need beforeFilter() to give that instruction to Auth component to allow signup(). The main thing here to learn is that before Auth component start it’s working, beforeFilter() is invoked . In this we are invoking two beforeFilters one of users controller and other on of app controller by using ` parent::beforeFilter();`

Second function is login(), which is basically called if you put ` http://www.your_domain_name.com/users/login/` in your URL of browser or if you try to access a restricted area of application. When you submit your data by ` login.ctp` file which is view file for this login function then Auth component starts working. First of all it hashes the password field of $data and passes this $data variable to Users Model. Then Model checks and results back to controller. If a valid user is found then Auth adds it in session and grants access to all functions to which it is authorized which is checked by isAuthorized(). But if it finds invalid user, it redirects back to ` login()`.

Third function is logout(), in this function we sets a session’s flash message to let user know that he/she has been logged out. On second line of this function we calling redirect method of controller, which is taking argument from ` $this->Auth->logout()` which is a string containing url to login method.

Our last method is signup(), this is created to add new users. In this we are using create() and save() methods of User Model. Create method initializes the model for writing a new record, loading the default values for those fields that are not defined in $data, and clearing previous validation errors. Especially helpful for saving data in loops. Save method saves model data (based on white-list, if supplied) to the database. By default, validation occurs before save.

login.ctp File

It holds presentation code.Code is…

<?php

echo $this->Form->create(array('action'=>'login));
echo $this->Form->input('username');
echo $this->Form->input('password');
echo $this->Form->end('Login');
?>

Explanation :

This view file utilizes Form Helper to create form elements.

signup.ctp File

It also holds presentation code.In this we have a form so user could submit it with data to create new user…

<?php

echo $this->Form->create(array('action'=>'signup));
echo $this->Form->input('username');
echo $this->Form->input('password');
echo $this->Form->end('Signup');
?>