Codeigniter paging. Methods to get info about total rows of they query using FOUND_ROWS(). ar_ prefix for versión >= 3 qb_ prefix for version < 3

DB_active_rec.php

<?php
  /*
   * Add this methos on the system/database/DB_active_rec.php file 
   */

  /**
   * 
   * Method to stablish the limit and offset
   */
  public function set_paging($page = 1, $results_per_page = 20)
	{
		$this->ar_page   = ($page > 1) ? --$page : 0;
		
		$this->ar_limit  = $this->ar_results_per_page = (int) $results_per_page;
		$this->ar_offset = (int) ($this->ar_page * $this->ar_results_per_page);

		return $this;	
	}

  /**
   *
   * Method to get paging info
   */ 
	public function get_paging()
	{
	  // Executing the last query again because all the info is reseted after executing the query
	  // ->query(...), ->get(...), ->get_where(...)
		$this->simple_query(preg_replace('/SELECT/', 'SELECT SQL_CALC_FOUND_ROWS', $this->last_query(), 1));
		
		// Getting the rows found
		$total = $this->query('SELECT FOUND_ROWS() AS "total";')->row()->total;

		$data = array(
		  // Total numbers of records of the last query executed
			'total'   => $total
			
			// Total number of pages
			, 'pages' => ceil($total / $this->ar_results_per_page)
			
			// Beccause we don't want to have a zero page we add +1
			, 'page'  => ++$this->ar_page
		);
  
    // Reset the values
		$this->ar_page = $this->ar_result_per_page = 0;

		return $data;
	}
	

example.php

<?php

function Pokemon_Model example CI_Model
{
  function __construct()
  {
    parent::__construct();
    $this->load->database();
  }
  
  function get_list($page = 1)
  {
    $results_per_page = 50;
    
    $this->db->select('pokemon_type');
    $this->db->group_by('pokemon_type');
    
    $this->db->set_paging($page, $results_per_page);
    
    $data['result'] = $this->db->get('pokemon')->result_array();
    $data['paging'] = $this->db->get_paging();
  }
}