ci-pt2-login-fn.php

<?php 

function login()
{
	// Set required fields
	$this->form_validation->set_rules('email', 'Email', 'required');
	$this->form_validation->set_rules('password', 'Password', 'required');
	
	if ($this->form_validation->run() == FALSE)
	{
		// Form has not yet been posted, load the login form page
		$this->load->view('login_form');
	}
	else
	{
		// Form validation passed and has been posted
		
		// Get the email field
		$email = $this->input->post('email');
		
		// Get the password and sha1() encrypt it to compare it to the version in the database
		$pass = sha1($this->input->post('password'));
		
		// Authenticate the user
		$user_id = $this->User_model->auth_user($email,$pass);
		
		if($user_id)
		{
			// Add the users id to the session.
			$userdata = array(
				'user_id' => $user_id
			);
			
			$this->session->set_userdata($userdata);
			
			// Users first login, taken them to the details page.
			redirect('/');
		}
		else
		{
			// The auth function return false, lets redirect back to this page so they can
			// fill in the login for again.
			redirect( current_url() );
		}
	}
}