We're going to create only one controller in this project, which is /path/to/codeigniter/application/controllers/tasks.php.

Let's go over that controller now, look at the code, and discuss how it functions.

Create the /path/to/codeigniter/application/controllers/tasks.php file and add the following code to it:

<?php if (!defined('BASEPATH')) exit('No direct script access allowed');

class Tasks extends MY_Controller {
  function __construct() {
  parent::__construct();
    $this->load->helper('string');
    $this->load->helper('text');
    $this->load->model('Tasks_model');
    $this->load->library('form_validation');
    $this->form_validation->set_error_delimiters('<div class="alert alert-danger">', '</div>');
  }

The index() function performs a couple of tasks: displaying a list of tasks and handling the form submission (validation, error checking, and so on).

Initially, we set the validation rules for the form, as follows...